IntroductionHigh tunnels are becoming increasingly popular for use by small farms who often marketdirectly to consumers. Although they have proven to be economically advantageous to farmerswho wish to capitalize on high prices obtained either early or late in the growing season,permanent high tunnel structures do represent a significant capital investment. The cost for astandard size tunnel, including plastic (two layers) and all the materials required for constructioncan range from $1.50-$2.50 per square foot without labor and freight charges. This represents aninitial investment of several thousand dollars, which is simply too much for some small farms.Although most growers are able to pay for their tunnels within a few growing seasons, otherscannot justify the investment. For this reason, extension and research personnel at the Universityof Kentucky have been working on developing a low cost high tunnel covered with a single layerof plastic that can be assembled or moved in an afternoon.This low cost high tunnel only provides about 3 oF in frost protection, compared to 7 oF for adouble poly tunnel. This tunnel design has proven to withstand 60 mph winds with little damagein central and western KY. This tunnel will not withstand much more than a very light snowevent (<1 inch), however it is not meant to be used through the winter in parts of the country thatreceive significant snowfall. The best time to use this tunnel is for a few months in early springand mid-fall that receive low daily temperatures and mild frosts. Demonstrations in Central andEastern KY have shown that growers can reach the market up to three-four weeks earlier withtomatoes grown in this tunnel than in the field. The added income from these early tomatoesmore than offsets the initial costs.Additional benefits from this type of design include the ability to make the tunnel as long as isnecessary. Because much of the labor is in constructing the endwalls, there is not as muchdifference in labor costs for constructing a 300 foot long tunnel compared to a 100 foot longtunnel. Obviously materials costs are more, but it allows flexibility for the grower depending onmarket conditions. Another positive for organic growers in particular is the ability to easilydisassemble the tunnel and move it from one location to another. One of the central tenets oforganic agriculture is the idea of crop rotation. Unfortunately with some of the more permanenthigh tunnel structures proper rotation is difficult. Often growers find themselves growing thesame crop in the same location for many years. Failure to rotate annual crops does not complywith organic requirements, and in many cases results in high levels of soil-borne diseases.Organic growers in particular have had to adapt to find creative ways to deal with these diseases,including grafting of resistant rootstocks, biofumigants, and soil solarization. Being able toquickly move a tunnel allows growers to easily rotate and avoids many of these problems. Thefollowing are step-by-step instructions on how to assemble this type of tunnel. This design isconstantly being modified to find the most economical use of money and labor while stillproviding a sturdy useful structure. Below is a detailed outline on how to construct this tunnel.Constructing the high tunnel
In this tunnel we have already laid plastic in the field and transplanted. By assembling the tunnelover the already formed beds we can use traditional tractor mounted bedshapers andtransplanters, saving the need for specialized equipment. Here anchors are made from one inchdiameter pieces of steel pipe 18 inches in length with a single turn of auger flight welded to theend. Photo credit: Tim Coolong, University of KentuckyThese anchors are placed on eight foot centers the entire length of the tunnel. Generally they arespaced 12 feet apart, which is enough to easily cover two beds made on six foot centers. Photocredit: Tim Coolong, University of Kentucky
The anchors are then augured into the ground with a small hydraulic driven motor which can behooked to a tractor. Anchors are driven into the ground so that the "hook" that is welded on theside is just at the soil level. Photo credit: Tim Coolong, University of KentuckyThen 1.5 inch schedule 40 pvc pipe is placed over the anchors. Typically pipe can be purchasedin 20 foot lengths. A 20 foot pipe will form a tunnel 12 feet wide at the based with a centerheight of just over six feet. Pipes should be painted with a latex paint. Experience has shownthat non-painted pipe may cause plastic to degrade where it comes in contact with the pipe.Photo credit: Tim Coolong, University of KentuckyEndwalls were constructed the previous season. These are made from 2x4 lumber and have anumber of aluminum channels attached to them for fastening plastic. They are quickly put in
place and attached to the end loops. In addition, ropes are run from either side of the door toanchors that are sunk deep into the ground. Mobile home anchors are inexpensive and work wellfor this purpose. Photo credit: Tim Coolong, University of KentuckyA lightweight metal pipe is then attached to each bow using aluminum cross connectors. Atypical source of pipe would be the top rail for a chain link fence. This pipe is very important asit gives the entire tunnel rigidity. Demonstration plots showed that tunnels with the center pipewithstood very strong (60 mph) wind gusts while those without the pipe did not. The rigid pipealso helps shed water after rains. Photo credit: Tim Coolong, University of Kentucky
Ropes are then attached to anchors at each end and attached to the first three bows on either endin crisscross fashion. These ropes help tighten the tunnel and improve end-wall stability. Photocredit: Tim Coolong, University of KentuckyPlastic is then unrolled and pulled over the house. Because the plastic is meant to be removedduring the winter months, a lighter weight (4 millimeter) plastic can be used if desired.However, 6 millimeter plastic has shown to be able to withstand wind to a much greater extentthan 4 millimeter in central KY. Once pulled over the hoops, the ends of the plastic are attachedto the endwalls using "wiggle wire" put into the pre-fastened channels (shown in the far rightphoto). Photo credit: Tim Coolong, University of Kentucky
Then nylon rope is fed back and forth over the plastic attaching to the hooks that were welded onthe side of the anchors. The rope is sent down the tunnel and attached to every other hook then itis brought back up the tunnel and attached to the remaining hooks. The rope is twisted at eachhook so that the rope can be easily tightened as needed. By using the rope to hold the plasticcover down, one does not have to permanently affix the plastic to any base. Therefore whenwarm weather strikes the plastic can be pulled up on each side easily venting the crop inside. Infact, this type of structure was used to grow organic colored bell peppers during the summer inLexington, KY. It served to keep rain off of the peppers, reducing fruit rot and the spread ofbacterial spot of pepper. Photo credit: Tim Coolong, University of KentuckyTotal assembly time for a 160 foot long tunnel from start to finish can be done with 2-3 people inabout 3-6 hours, depending on experience level. The end walls would take an individual about 2hours each to build. While these tunnels only give about 2-3 oF of frost protection alone-more ifan additional layer of plastic or remay is placed in the tunnel, they effectively increase thenumber of hours above 50 oF when used in spring. Thus they promote rapid growth and earlyfruit when used for tomatoes. Above is a picture taken on June 20, 2008, in the mountain regionof East KY. The plastic had been removed, but one can easily see the difference in growth andfruit set on the tomatoes Mt. Crest planted in the tunnel and those outside the tunnel. Both wereplanted on the same day in late April 2008. While not for everyone, these inexpensive tunnelscan give growers a jump on the season without a large investment of capital. Photo credit: TimCoolong, University of Kentucky
This is an eOrganic article and was reviewed for compliance with National Organic Programregulations by members of the eOrganic community. Always check with your organiccertification agency before adopting new practices or using new materials. For moreinformation, refer to eOrganics articles on organic certification.High Tunnels in W.Va.By Lewis W. Jett, Horticulture Specialist, 2010Figure 1. High tunnels are passively vented, solar greenhouse structures covered with a single or double layer of polyethylene plasticHigh tunnels are passively vented, solar greenhouses that are used to lengthen the production and marketing season of vegetable and fruit crops(Figure 1). No artificial heating/cooling or ventilation system is used within the high tunnel, and the only external connection is water for drip or micro-irrigation. Most high tunnels are covered with a single or double layer of polyethylene plastic (6-mil; greenhouse-grade) and have a useful life of 20years if properly constructed and maintained. Crops within high tunnels are usually grown directly in the soil rather than artificial growing media, butsoil-less substrates (perlite, compost, water) can be used for crop production within high tunnels.High tunnels are very effective in collecting radiant energy from sunlight and using this energy to increase air and soil temperature to accelerate cropgrowth. Thus, in areas with abundant sunlight, high tunnels will be very effective for early-season harvest and lengthening the growing season.High tunnels facilitate intensive crop production on a small land area and are conducive to sustainable farming practices such as intercropping, covercropping, compost application and biological pest management. Crops within the high tunnels are protected from environmental stresses such asdrought, wind, hail, rain and intense sunlight. Heavy rainfall prevents soil erosion within the high tunnel. The dry environment within the high tunnelkeeps the plant canopy dry and reduces diseases and weed growth. High tunnels also physically exclude many pests from attacking the crop includinginsects and wildlife. As a result, many growers use high tunnels for organic production of fruits and vegetables. High tunnels have significantly lowerinvestment costs and annual operating costs than standard greenhouses.Figure 2. The site for construction of a high tunnel should be accessible, well-drained with abundant sunlight. (Photo Credit: E. Coleman)The first step in high tunnel crop production is choosing a suitable site for the structure (Figure 2). Most high tunnels are permanent structures, so thesite chosen will be the area for crop production for several seasons. Depending on location, building permits may be required. The site should have nohistory of perennial weeds or diseases and be well-drained and free of large stones. A soil test should be conducted in advance of choosing the site forthe high tunnel. Since high tunnels are manually vented, they should be accessible. Water is an essential input for high tunnels, so access to water(surface or well) is necessary. While most high tunnels do not require electrical inputs, some growers choose to have electric fans which circulate air orinflate air between double layers of polyethylene.High tunnels do not have to be constructed on perfectly level land, but a building pad or terrace can be made prior to constructing the high tunnel.Slope along the length of the high tunnel will facilitate water movement but should not be greater than 3%. Slope across the width of the high tunnelcan be compensated by adjusting the height of the ground posts on either side. The construction pad can have sloping sides to channel water andsnow runoff from the high tunnel structure.
The site should have full sun and good air flow since these are essential inputs to how well a high tunnel functions. Low areas that accumulate cold air(frost pockets) and water or sites close to a tree line or other structures which may cast a shadow on the high tunnel structure should be avoided. Also,areas with strong wind should have a wind break to prevent excessive wind stress or snow accumulation against the structure.Orientation or positioning of the high tunnel is site dependent. The primary criterion should be maximizing passive ventilation. Therefore, for suitableventilation, the high tunnel should be oriented so the length of the structure is perpendicular (i.e., at right angles) to prevailing winds at the site. In WestVirginia, a north-south orientation is optimal for cross ventilation. Above the 40° latitude, most high tunnels are oriented in an east-west direction formaximum light interception particularly during low light months of winter. Most of West Virginia is below 40° latitude, so orientation is based onmaximizing cross ventilation. Generally, the strongest winds which can damage the structure occur from the north-northwest in West Virginia, so anorth-south orientation allows this potentially damaging wind to hit the smallest surface area of the structure (i.e., the end wall).Figure 3. Quonset- (top) and Gothic- (bottom) shaped high tunnels.High tunnels vary in length, width and shape. Ideally, the high tunnel should be at least tall enough to walk in with ease (> 7 ft.) or for equipment to betaken into the structure to till the soil, apply compost or create raised beds. Most high tunnels are 15-30 feet wide; 9-15 feet high and up to 200 feet inlength (Figure 3). Optimal length for an individual structure with roll-up sides is approximately 100 feet. Many growers will start with a short, widestructure (e.g., 30 ft x 48 ft) and add on to the length in subsequent years. A shorter, wider structure is superior to a longer, narrower structure sincethe former will have less area exposed to the outside environment.Larger high tunnel structures tend to store more heat during the day and are less likely to overheat. At night, when maintaining a stable temperature iscrucial, larger high tunnels are less likely to cool down as rapidly. In addition, a taller high tunnel allows warm, buoyant air to rise in the structurefacilitating ventilation.There are two main structural designs for high tunnels: Quonset and Gothic. Quonset structures have a round roof with slightly shorter and curvedsidewalls (Figure 3, top), while Gothic structures has a pointed peak (A-frame) with straight sidewalls (Figure 3, bottom). Gothic structures tend to shedsnow and ice better than Quonset structures. Gothic structures also allow for a peak or gable vent to be added to the structure which facilitates airmovement and ventilation.Figure 4. (top) Sidewalls are rolled-up to facilitate cross-ventilation within the high tunnel. (bottom) PVC-framed high tunnels are functional hightunnels.Sidewalls on the high tunnel structure are usually rolled-up to facilitate cross ventilation (Figure 4, top). Therefore sidewalls should be at least 5 feet inheight to maximize ventilation. During inclement weather, the sidewalls are closed.If the site for high tunnel construction encounters significant snow or wind stress throughout the year, cross-braces (bracing of the bows) or othersupplemental bracing of the frame may be necessary to strengthen the structure. Frames for high tunnels are usually galvanized steel but othermaterials can be used. Wood frames have been used as framing material for high tunnels. However, there is more blockage of sunlight from the woodframe than by other framing materials. Polyvinyl chloride (PVC) has also been used as a framing material for high tunnels (Figure 4, bottom). MostPVC-framed high tunnels are smaller in width than steel-framed structures. While PVC high tunnels can be lower in costs, they tend to be vulnerable todamage from wind, snow and ice unless they are properly braced.After the site and general design of the high tunnel has been chosen, the structure can be constructed. Both spring and fall are excellent times of theyear to build a high tunnel. The soil is amenable to construction, and the air temperature is suitable for pulling and stretching plastic over the structure.If building on a site which is presently in sod, the sod can be tilled after most of the high tunnel has been constructed.
Figure 6. The high tunnel structure must be square at each corner post.The next step is to place the corner ground posts of the high tunnel so that the structure is ultimately square. The Pythagorean Theorem can be usedto establish a 90° angle at each corner. The Pythagorean Theorem states the square of the hypotenuse of a 90° triangle is equal to the sum of thesquares of the other two sides. Once one corner is square, the other three corner posts can be set so that the diagonals (length from one corner postto the opposite end corner post) are equal (Figure 6). For example, a 30 ft x 96 ft high tunnel will have a 100.5 ft length diagonal (302 + 962) if thestructure is square.Figure 7. Corner posts can be set in cement to provide strength for the high tunnel structure. A leveling line is used to ensure each ground post islevel. (Photo credit: A. Montri)After the corner posts have been squared, they can be backfilled with cement to provide support for the structure (Figure 7). Obviously cement makesthe structure permanent, so if there are plans to move the structure in the future, this step may be avoided. The remaining high tunnel ground posts aredriven into the soil as straight as possible to various depths (usually no less than 18 inches) with a sledge hammer or post driver. A post level will bevery useful in making sure each post is plumb. Also a leveling line (mason twine) connected to the bolt holes of each corner post can be used to driveeach post to a depth which is level. A positioning or spacing jig can be used to evenly space the ground posts. Most ground posts are placed 4, 5 or 6feet apart, with 4 feet the recommended spacing for high tunnels in West Virginia.Figure 8. Purlins, cross braces, base boards and hip boards are attached to each bow to provide stability to the high tunnel frame.The bows of the structure typically are 2-3 pieces and can be loosely assembled on the ground. Each bow is then inserted into the ground post andsecured with 1-2 carriage bolts. Placing each bow in the ground post will require approximately 3 workers. After the bows are secured in place, thepurlins should be attached to the bows. Purlins are smaller diameter pipes which are bolted (or clamped) to the bows to provide stability to the structure(Figure 8). Each high tunnel frame should have 1-3 purlins. Cross-braces can be attached to provide increased strength to the high tunnel frame.After the purlins have been added to the structure, the baseboards and hipboards can be placed on the high tunnel. Baseboards and hip boards addstrength to the base of the frame (Figure 8). For most high tunnel frames, 2 inches x 6 inches x 10 feet wood (or recycled plastic) boards are suitable.Pressure treated wood can be used for both hipboards and baseboards. Each section of baseboard is bolted onto the ground post or secured with apipe strap (Figure 9). The baseboard and hipboard must be level across the length of the high tunnel. Each joint between sections can be spliced witha small segment of board.Hipboards are attached 5-8 feet above the baseboards (Figure 8). Hipboards provide additional strength to the structure and are the boards in whichthe plastic covering the high tunnel structure is attached. Aluminum channel lock can be secured to the hipboard to provide a location for securing theplastic (Figure 9).
Figure 9. Pipe straps are used to secure the baseboards and hipboards to the high tunnel frame. Aluminum channel lock is used to secure the plasticto the frame.After the frame has been assembled, the end walls can be constructed. End walls vary in design from a simple fabric curtain to a wood-framedstructure with doors (Figure 10). End walls provide strength to the high tunnel and should be built to provide easy access of people and machinery. Endwalls can be covered with polyethylene plastic, polycarbonate or plywood. The north-facing end wall can be covered with double layer of polyethyleneplastic to provide greater protection from the north wind. Some growers will completely remove the end wall coverings during warm weather.Figure 10. There is a diversity of end wall designs for high tunnel structures.The plastic covering can be placed over the high tunnel structure after construction of the frame and end walls has been completed. There are manytypes of greenhouse plastics, but the plastic should be a UV- (ultraviolet light) treated plastic, 6 mil in thickness, with a useful life of approximately 4years. IR (infrared) blocking plastic is also available and will provide better heat retention. A calm day with moderate temperatures will be optimal forcovering the structure. Plastic should not be pulled over the structure if temperatures are lower than 60° F since it will be difficult to obtain a goodstretch on the plastic. Ideally, the plastic should be taut and not flap against the bows.Figure 11. Plastic (poly) is used to cover the high tunnel structure. The plastic is pulled over the frame after securing it with rope wrapped aroundtennis balls.At least 4-5 people will be needed to pull the plastic over the high tunnel. The plastic comes in a roll which is unrolled along the length of the house(Figure 11). After unrolling the plastic, a handful of the plastic can be folded around a tennis ball at various distances. Rope is then tied to this ball andthrown over the frame (Figure 11). Carefully, the plastic is pulled over the structure, making sure it is square with the frame.The plastic is attached to the frame with wiggle wire or polylock placed in each aluminum channel lock on the hip board (Figure 12, left). One sideshould be completely secured first then any slack in the plastic can be pulled and the other side wired. The plastic should be as taut as possible. Thechannel lock on the end bows are used to hold the plastic to the end walls of the high tunnel. The plastic is clamped on to a metal roll bar (purlin pipe)which serves as the bar for rolling the plastic up or down on each side wall. A “T- or L”- shaped handle can be made to serve as a hand crank whichmakes rolling the pipe up easier. Rope can be laced on the sidewalls to hold the plastic sidewall closer to the frame and prevent flapping in wind(Figure 12, center).
Figure 12. (left) Plastic is secured to the frame with wiggle wire within each channel lock. (center) Rope can be laced along the sidewall for tighteningthe roll-up sides. (right) Water runoff from the high tunnel can be collected and used for irrigation.To prevent excessive water movement into the high tunnel, a drainage ditch should be dug to channel water away from the high tunnel. A wovenlandscape fabric can also be used to divert excess runoff water and prevent weeds from growing close to the high tunnel. Rain gutters can also besecured to the hipboard and used to channel water into a storage tank that can be used to irrigate crops within the high tunnel (Figure 12, right). Battentape can be used to secure the plastic to the end wall frame. Batten tape is applied over the plastic and stapled into place.Additional High Tunnel Construction Resource Material:The Hoophouse Handbook. 2003. Growing for Market. L. Byczynski (ed.).The Winter Harvest Handbook. 2009. E. Coleman. Chelsea Green Publishing Co., White River Junction, VTHigh Tunnel Production Manual. 2008. Penn State Center for Plasticulture.Yard & Garden Line NewsVolume 6 Number 15 September15, 2004Features this issue:High Hopes for High HoopsGolden Rust on GoldenrodsWest Nile Virus Cases DownIncorporate All-America Selections into Next Years GardenLate September Garden TipsEditorial NotesHigh Hopes for High HoopsRobert Olson, Regional Extension Educator, Horticulture
Major componentsIllus: Penn StateBasic structure, uncovered.Field vs. tunneltomatoes on Aug. 18,in Gr. RapidsUp to 8# from some indoorplants. None in field.Photo Credits: Bob OlsonOnions: field vs tunnel-grownPhoto Credit:Terry Nennich
This summers dismal weather has prompted a lot of interest in garden structures that extend the growing season. Tops on this list are "high hoops" - also called "high tunnels" or "hoop houses". There names are interchangeable, and theyve become the most popular form of greenhouse structure for many reasons.Tall enough High hoops were originally designed for commercial growers, but theirfor staked plants. popularity has lead to the development of smaller structures that arePhoto Credit: being utilized by backyard gardeners. Regardless of size, the workingBob Olson principles are the same.What are they?High tunnels are unheated, plastic-covered structures that provide an intermediate level ofenvironmental protection and control as compared to open field conditions and heatedgreenhouses. Plantings in high tunnels are placed directly into the existing soil of your farm fieldor garden, as opposed to production on benches or raised platforms like in greenhouses.High tunnels are tall enough to walk in comfortably and to grow tall, trellised crops. Homeownermodels that are 14 feet wide reach an interior height of about 8 feet; commercial models that aretypically 30 feet wide reach a height of about 15 feet. The commercial models also have endpanels that allow small tractors to drive through.Greenhouses are permanent structures that are taxed as real property, whereas high tunnels(being temporary, moveable structures) are not. Greenhouses are covered by glass, rigid panelsor double-layer plastic, but high tunnels are covered with a single layer of plastic.A critical component of high tunnels is their ventilation system which generally consists of roll-up sidewalls that can be opened in the morning and rolled down at night or in cold weather.Because the entire system is enclosed, no rainfall enters the tunnel. All water is supplied by thegrower, generally via trickle tubes that are placed under plastic. The interior of the tunnel iscompletely dry and relatively clean. Harvested produce is very clean, greatly reducing thewashing of produce. Research validates that fresh produce from tunnels also has enhanced shelflife as compared to field-grown produce.Unlike commercial greenhouses that can cost up to $20 per square foot to construct, high tunnelscan cost as little as $0.50 per square foot. This modest cost can result in a high return oninvestment, and in a season like this year growers with high tunnels reported that they paid forthemselves the first season. Proponents of the tunnels see them as great income-generatingtechnologies that college students and enterprising high-schoolers could manage as a summerjob. One commercial-scale tunnel (30 feet X 90 feet), costing under $2000 to construct, couldgross over $6000 if planted to tomatoes that are sold at farmer markets or roadside stands.Unexpected BenefitsEveryone expected tunnels to provide a heat advantage compared to field-grown production.Few people, however, expected the dramatically reduced pest levels that are being realized.
Growers and researchers alike are impressed with the excellent weed, insect, and disease controlwithin the tunnels. Growers that have been cautious about organic production are now givingorganics another look.Reduced disease One of the most impressive features of these systems to date is the diminisheddisease pressure. The tunnel systems, by keeping the interior completely dry, result in anenvironment less conducive to several of the problematic disease organisms. Think about it, thefoliage is always dry and there is no soil splashing compared to field grown systems. Add to thisthe wind protection factor from blowing soil and the enhanced vigor of plants, and you have anenvironment that allows crops to out-compete pests.A critical component to managing diseases is the sidewall ventilation system. Without the opensides, the humidity levels would lead to a rainforest environment and subsequent disease haven.So during most days, the sidewalls are rolled open. When nighttime comes, the grower closes thetunnel to keep the cooler evening air from condensing on the leaf surfaces, thereby keeping thefoliage completely dry. Just walk your lawn in bare feet after sundown and youll know just howwet foliage can become. Im reminded about condensation every winter morning when I scrapethe ice from my cars windshield, whereas the cars parked in the garage are nice and dry. Itmakes me wonder, why is it that I am the one who pays for the cars, the insurance, the mortgage,and puts gas in the cars, yet Im the one who has to park outside in the cold? I digress.More InformationIf your interest is piqued, youll probably want to do a little research on the subject. Mycolleague, Terry Nennich, is developing a written manual on high tunnel management based onMinnesota research which will be designed for commercial growers. The principles will beapplicable to the backyard gardener as well. Another great source for information is Penn State,which has a large research effort devoted to plasticulture, including high tunnels. They can beaccessed at: http://plasticulture.cas.psu.edu/.Golden Rust on GoldenrodsJanna Beckerman, Extension Plant PathologistSevere infection ongoldenrod.
This year has been an interesting one for plant pathologists. As our long, cool wet spring, became a cool, dry summer, a variety of diseases that are commonly overlooked became unusually severe. One such disease is pine needle rust. However, the severity of this disease manifested itself most severely on the alternate hosts: Goldenrod (Solidago spp.) and Aster (Aster spp.)Individual To make surepustules When forest pathologists discuss pine needle rust, the disease isproduce they refer to the economically important timber rust, check yourthousands of hosts of jack (P. banksiana), Austrian (Pinus nigra), hands for spores,spores. but not whileAll Photos: red (P. resinosa), ponderosa (P. ponderosa), mugo trying to take aJanna Beckerman (P. mugo), and Scots (P. sylvestris) pine. photo at the Economically speaking, the alternate hosts are of same time!little value-except to the homeowner whose plant is suddenly orange. Thisdisease is caused by the fungus Coleosporium asterum. Although it doesnt look that way, thisrust causes little damage on either host. In pines, browning and needle death on lower branches isunattractive, and may slow the growth of young pines. On goldenrod and aster, severe infectionmay result in a reduction or loss of flowering.The life cycle of pine needle rust takes an entire year to complete. Currently, on the aster andgolden rod, we are seeing the uredinia developing on the leaves and stems. This stage can repeatitself under conducive weather conditions, and render the entire plant orange, as weve seen!Eventually, urediniaspores produce a new spore shape, the teliospore. The teliospores germinatesto produce basidiospores that are windblown to pine needles, where new infections begin. Theseinfections will not be seen until next spring.In the meantime, the fungus survives winter in the infected pine needles. The following spring,small yellow spots appear on infected needles that develop into columns that split releasingorange spores. These spores are wind- dispersed and infect the underside of leaves of thegoldenrod and aster. Orange structures called uredinia develop on the leaves and produce thecharacteristic orange spores that we are seeing now.When diagnosing rust diseases, it is important to actually see spores! Plants turn orange for manyother physiological reasons (nutrient deficiency, insect feeding, herbicide damage, etc.). Findingspores on your hands is a tell-tale sign to diagnose this disease!Although pine needle rust rarely causes damage to mature trees, it can render plantings of astersand goldenrod unbelievably orange. Fungicides labeled for the control of rust on perennialscontain active ingredients like sulfur, chlorothalonil, myclobutanil, and mancozeb. Replacingplants with rust resistant asters Removal of alternative hosts from the immediate vicinity of thetrees will reduce infections of pines. Cultural practices such as thinning foliage, watering duringdry periods, mulching, and fertilizing may reduce infections. Reportedly resistant goldenrodcultivars include: Baby Sun, Baby Gold and Goldkind. The PREP trial in Rosemount has
found that Aster Alma Potshke was very resistant to rust, but that the A. dumosas series WoodsPink and Woods Purple were very susceptible and susceptible, respectively. Please check out the new diagnostics web pages at http://www.extension.umn.edu/projects/yardandgarden/diagnostics/West Nile Virus Cases DownJeffrey Hahn, Assist. Extension Entomologist Although many Minnesotans will think of 2004 as the summer that never was, we may also remember it for the low incidence of West Nile virus (WNV) that we experienced. Our first detected activity of WNV in Minnesota occurred in 2002 when we recorded 48 human cases and zero deaths. In 2003, the number of human cases tripled to 148 alongDisease outbreaks with four deathsImage: CDCThe big question was what would happen in 2004. Would the number of cases continue toincrease? Unfortunately, entomologists and vector ecologists dont know enough about thisdisease to accurately predict how the disease will cycle. But fortunately instead of continuing togo up, the number of WNV cases have fallen. So far this year, there have been only 19 cases andone death recorded in Minnesota (as of September 14, 2004). Although more cases are likely tobe reported before the end of the year, (most cases in Minnesota are reported during August andSeptember) the majority have undoubtedly occurred.Interestingly, the number of horse cases this year are also considerably down. To date, there haveonly been 6 instances of horses infected with WNV. This is after 992 cases in 2002 and 74 caseslast year. Although there may be several factors that help explain this, much of this decrease isprobably attributable to the increased protection of horses that owners have given them,especially by vaccinating them.However, there is not such an easy answer for humans to explain why the incidence of WNV hasgone down. It is natural to assume that the cooler weather had a significant effect on WNV cases.While it is true the weather probably did slow down mosquito activity, it is unlikely the onlyreason. There does seem to be a consistent trend in other states for the rates of WNV to cycledown after a large increase of WNV has been first detected, although the exact reasons are notclear.It is interesting to look at New York, the first state to record WNV. In 1999 they detected 62human cases of WNV with seven deaths. Those numbers went down in 2000 to 14 cases, zerodeaths and to 15 cases and two deaths in 2001. The number of human cases rose in 2002 to 83(five deaths). In 2003, activity was down to 71 cases but with 10 deaths. So far in 2004 therehave been only 5 cases with no deaths. Although the incidence of WNV may go up, it alwaysseems to come back down to very small numbers. (Keep in mind that for a state with such a largepopulation as New York, 100 or fewer cases is just a small percentage of the overall population).There isnt an easy explanation for this pattern in New York or similar cycles in other states,
including Minnesota. That makes it difficult to predict whether the current trend in Minnesotawill remain in a downward cycle or fluctuate. The disease is too new here to understand itcompletely. We need to continue to learn about WNV to better understand what our potentialrisk may be.For more information, see also the Minnesota Department of Health West Nile virus web site,http://www.health.state.mn.us/divs/idepc/diseases/westnile/index.html Get the low down on this months insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htmIncorporate All-America Selections into Next Years GardenDeborah Brown, Extension Horticulturist Its always fun to try new seeds, and when the flower or vegetable is an All America Selection winner, its a pretty good bet that it will perform well in your garden. Heres a sneak preview of the All America Selections chosen for 2005. You should be able to order seeds from a number of Tomato Sugary All Photos: mailorder or Internet catalogs. Some winners will AAS also be available as young transplants in packs atGallardia Arizona Sun local nurseries and garden centers. Flowers: Gaillardia ‘Arizona Sun, also known as "blanket flower," is a neat, compact cultivar suitable for container growing. Blanket flowers are usually short-lived perennials in our climate. Should you hope to over- winter it, plant it in the ground rather than in a container. Catharanthus ‘First Kiss Blueberry, usually called "vinca," is the bluest yet produced, but its still a violet-blue rather than sky blue. Vincas haveVinca First glossy, leathery leaves and can take sunny, hot, dry conditions. They alsoKiss Blueberry bloom in light shade, though not as well as in a sunny site.Zinnia ‘Magellan Coral produces double flowers, five to six inches across! It blooms early –only six to nine weeks from seed – and, like other zinnias, grows best when seeded directly intothe garden.Vegetables: ‘Fairy Tale eggplant is pretty enough to categorize with the flowers instead of thevegetable winners. The petite plants produce small purple and white striped fruit that are tenderand tasty when anywhere from one to four ounces in size.‘Sugary tomato produces grape-like clusters of ultra sweet "cherry" tomatoes that are oval, witha little point on the end. They can be harvested about sixty days after transplanting, and may begrown in large containers or supported, directly in the ground.
‘Bonbon is a winter squash with an upright, semi-bush habit, requiring less garden space thanmost winter squash. The boxy, four pound fruits are said to have superior eating quality – sweet,with a creamy texture. They ripen roughly eighty-one days from planting, sometime the latterpart of August in southern Minnesota.Late September Garden TipsBeth Jarvis, Yard & Garden LineCompiled from conversations with Patrick Weicherding and Bob Mugaas, Regional ExtensionEducators.These recommendation are based on Twin Cities temperatures. Adjust for northernMinnesota.Trees and Shrubs:Water trees, especially those 5 years old or less. Older trees, theoretically, could be damaged byheavy watering because it could prompt new growth that cant be supported by drought-damagedroots. However, recent substantial rains will lighten the drought stress on established trees,especially since theyre shutting down in preparation for winter. Soil moisture is an important aidin the development of the abscission layer, so the rain will help the leaves fall. Drought stressedtrees will hold leaves well into the winter.Water all evergreens and young trees until the ground freezes. Water deciduous trees and shrubsas best you can until the leaves fall. Remember that lawn grass captures the vast majority ofapplied moisture, so water more than an inch within the dripline of trees. The soil should bedamp at least 6-8". Plase see: http://www.extension.umn.edu/yardandgarden/YGLNews/YGLN-Sept0103.html#water"Early fall color is a drought response indicating that the trees cant support the leave they stillhave. Poplars/cottonwood and ash are typical leaf "shedders" when stressed. Maples are anotherissue--thats maple decline--when trees are so stressed they cant recover.Pruning for cosmetic or structural purposes should wait until the dormant season. Removediseased trees now. Be sure all elm firewood has been de-barked before storage.Hold off on pruning trees susceptible to fire blight right now. Wait until late winter. The mostcommonly affected are: pear, apple, crabapple, mountain ash and cotoneaster. Read about it at:http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/p223fireblight.htmlShop fall tree sales. Pick well shaped trees with wide branch angles where applicable, anddesired fall color. Plant in the ground by the middle of October.Start thinking about rodent protection of new trees--it should go on before November 1, so shoparound for 1/4" hardware cloth to surround tender-barked young trees.Lawns:
Its a great time for perennial broadleaf weed control.Were coming up to the tail end of seeding, though if it stays warm and rains, the rest ofSeptember could be suitable. Sooner rather than later is the key as grass needs to be establishedbefore winters cold arrives.Sodding can be done for another month or so.If you overseed, work up the soil so you get good soil to seed contact. Tossing seed on a thatch-covered lawn will accomplish nothing.You can start reducing mowing height. A 3" cut can be reduced to 2.5". This will reducefloppiness that can help reduce future snow mold problems and increase growing points/densityof plants.Be sure to water if we get into a dry spell, even though temperatures may be cooler.Wait until closer to the end of October for the late season fall fertilizer application. If your grassis a bit anemic now, a half pound of nitrogen per thousand square feet of lawn could be appliednow followed by the late fall fertilizer application of a full pound of nitrogen.Core aerating is still possible. Dethatching should wait until spring. If you have heavy thatch, doa a real thorough core aerating job now. Grass needs 6-8 week of recovery time.Everything you ever wanted to know about lawn care and repair can be found at the SustainableUrban Landscape Information Series website at: http://www.sustland.umn.edu/maint/index.html.Click on lawn maintenance and scroll down to the lawn care calendar for timing.Flowers:Plant spring flowering bulbs soon. All but tulips need to be planted early. Tulips can be plantedas late as you can dig in the ground. For more info, see Spring Flowering Bulbshttp://www.extension.umn.edu/projects/yardandgarden/ygbriefs/h120bulbs-spring.htmlAs plants yellow and die back, its ok to cut them back and compost any healthy plant tissue.Editorial Notes Joe Pye weed is noted for growing taller in the wild and staying shorter in cultivation. It could be a light issue, as wild plants may be trying to grow into more light. This photo, taken at Eloise Butler Wildflower Park many years ago, was in an opening in the woods and quite tall.Joe Pye weed in wild In the next issue, Bob Mugaas, Regional Extension Educator,Photo credit: Horticulture, will be writing about why lawns flower and set seed in theBeth Jarvis spring. The process starts in the fall. That will be published Oct. 1. Ive
asked a couple of grad students to write a piece on the physiological changes plants, other thanturf grass, undergo in order to flower. In the future, Patrick Weicherding, Regional ExtensionEducator, Forestry, will be writing about new research findings on the timing of pruning trees fordisease prevention and to prevent pruning damage.Please feel free to cut and paste any of the articles for use in your own newsletters. All we ask isthat you give our authors credit.Back issues Yard & Garden Line News are on the Yard & Garden Line home page atwww.extension.umn.edu/yardandgarden/. Deb Brown answers gardening questions on Minnesota Public Radios (MPR) "Midmorning" program on the first Thursday of every month at 10 a.m. The program is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations.For plant and insect questions, visit http://www.extension.umn.edu/askmg. Thousands ofquestions have been answered, so try the search option in the black bar at the top left of the boardfor the fastest answer.If you would like to receive an e-mail reminder when the next issue of the Yard & Garden LineNews is posted to the web, just send an e-mail to: email@example.com (note: the second E inlistserve is omitted), leave the subject line blank, then in the body of the message, type: subyglnewslist or to unsubscribe, enter: unsub yglnewslistHappy gardening!Beth JarvisYard & Garden Line Project Coordinator Previous Page University of Minnesota Extension Service Home PageIn accordance with the Americans with Disabilities Act, this material is available in alternative formats uponrequest. Please contact your University of Minnesota county extension office or, outside of Minnesota, contact theDistribution Center at (612) 625-8173.The University of Minnesota Extension Service is committed to the policy that all persons shall have equal access toits programs, facilities, and employment without regard to race, color, creed, religion, national origin, sex, age,marital status, disability, public assistance status, veteran status, or sexual orientation.
Building a High Tunnel Hoop House / Green House : Part 1 BY ANDY, O N M AR CH 21 ST, 201 1Quite a while back we asked for input on Facebook from everyone to see what YOU would do if you were out here on thefarm… the question was – would you buy a JD Gator or would you buy a greenhouse? The results were split 50/50 so weknew we needed to make both happen. As you know – the Gator transaction was completed a while back… As for thegreen house / hoop house… well, construction started this weekend. The process is actually very straightforward and weare moving through the steps at a pretty rapid pace. Basically we bend all the tubing we need for the hoops, we poundsome slightly larger diameter tubes about 4 feet into the ground, screw the arches together and slip the arches into thetubes. We start with standard line posts for a chain link fence and cut them into 4′ lengths with a metal cutting blade onthe 12″ chop saw.The tools for pounding the tubes into the ground are pretty simple and with the ground being so wet right now the process is actually pretty easy. First we marked off the house with string in a 12′ x 28′ rectangle. Then using a mallet the post gets pounded about 6″ into the ground. The level and the big post driver help get it father down and straight too. Thelast 6″ takes a sledge hammer… that tends to round over the top of the pipe in the ground but as long as the 1 3/8″ pipesfor the hoops fit we are OK. If the opening gets too small, we use a bar to pry open the rolled metal. Very simple process actually.To bend the tubes we mounted a 3/4″ sheet of plywood on the back of our Gator and then mounted the tubing bender tothat. Then it’s a little elbow grease and a lot of back pulling to make the straight tubes that were bought at Home Depotfor chin link fencing into the curved halves of the hoop structure. Once we got the mechanics worked out I can feed andbend and Kelli can pull and keep the tube flat. It takes about 30 seconds to bend half a hoop.
After bending the tubes Kelli removes them from the opposite end of the device and then stacks them in the barn. Theends are painted to match the corresponding other half of the arch so when they go out to the field we know which onesgo together. To build this particular structure we need 28′ of support which is one arch every 4′… so that’s 7 arches, plusone for the end… and 2 bars per arch… calculator says… 16 total tubes bent.
The last step is the most rewarding… inserting the ends of the arches into the tube in the ground. The arch (or hoop – that’s why they call these a hoophouse) measures about 14′ wide when it’s not flexed so we “squeeze it” down to 12′ tomake the hoop house structure. The insertion of these hoops under tension adds a great deal of strength to the finished structure. As it sits now you can see we installed a single hoop mainly to feel good about our efforts… but to the left of the pictureyou see a whole bunch of pipes laying in the weeds waiting to be driven into the ground so we can attach more hoops. Westill need to build the base around the hoops out of some pressure treated 2×8 lumber, install a support along the spine of the structure, build some ends and then finally install the plastic… that’s ALL. If you liked this post, check out these: Building a High Tunnel Hoop House / Green House : Part 2 - (Really Similar) Building a High Tunnel Hoop House / Green House : Part 3 - (Really Similar) Dampening Off! - (Interesting) Gators and Greenhouses and Greenbacks, ohh my! - (Interesting) Building a High Tunnel Hoop House / Green House : Part 2 BY ANDY, O N AP R IL 10 TH , 20 11Just to set the record straight before we get into this… The last post on Pigs Milk Cheese was an April Fools post (nice job to those who caught the date). Also – if you haven’t ordered your pastured chicken yet – you should. With the posts in the ground (from the first post) there’s still a fair amount of work to be done, we needed to get a wooden base around to frame up an attachment point for the double layer of plastic. Wealso need to get the hoops installed, the spine installed and then some nifty wind bracing installed so we have a prayer ofsustaining those 60 MPH+ winds we get on the hill here without watching our hard work blow into the next county. So we started with the base boards. normally people install larger treated 2x something boards – but looking at the price of lumber we decided to go with a much less expensive treated 5/4×6 non-premium decking board. In reality, these base boards don’t offer much more that a place to attach the plastic so there’s no need to them to be super heavy duty. They are attached by drilling a hole through the board and the post and then attaching with a 1/4″ stainless bolt and nut. The challenge of installing the the base boards is really all about level ground. The posts were driven in toan approximation of “level” – but adding the base boards required a fair amount of finagling. All said and done, the lower
end of the structure has the baseboard about 4″ above the soil and te high end has the boards about 3″ into the soil. And we picked one of the more level areas to site the greenhouse!With 3 sides of the base completed (we left the end with the door open as it cuts through the existing low tunnel AND weare still debating about making the end door tractor friendly as well) it was time to start to assemble the superstructure, and all that starts with an end. So, we used the backhoe to dig a couple of 3′ deep holes and dropped some old treated 2×4′s in. Those were then lined up with the end hoop, cut to length, notched and bolted to the hoop itself. The spacing for the end posts we determined by the 2 tripple track storm windows that came off the barn when we resided it. They are big and will provide LOTS of ventilation on the west end of the green house. Once that “wall” was built, the process really takes off. It becomes an exercise in joining the 2 halves of the hoops we bent with stainless self tapping metal screws, then inserting them into the posts that are attached to the base boards. After all the hoops are up, the next step was to use some special (and expensive) clamps designed to attach the spinedown the top ridge line. This addition locks all the hoops into a single structure and really provides a massive amount ofrigidity to the structure. Up until this point we kinda felt like we were kids making a sandcastle at low tide… just waitingfor the wind to pick up and blow out wiggly metal structure into 100 little pieces. But with each rib being attached to the spine (yes, I loved Moby Dick), the whale of a structure became more and more solid. After the last section of the spine was installed and cut to length all we had left todo was install a set of diagonal wind braces and the windows. All in all, the steps in this part of the installation only took about 5 hours over 2 days and were the most rewarding steps. We can now stand back and look at something that resembles a green house. And the mostrewarding part has been the discovery of how strong this structure really is. The spine and the wind bracing has made the and wall solid and we really think this structure is going to be able to take the winds. As a matter of fact we are already thinking of LOTS of ways we can expand this design for something like a roaming pasture warmer for the chickens in the middle of winter… At any rate, tonight we place the order for the plastic, inflator fan and various other parts. Time marches on and our seedlings in the basement are getting ready for a nice warm “real sunlight” house!
For a few more pictures of the process – visit our Flickr Photostream to check things out. If you liked this post, check out these: Building a High Tunnel Hoop House / Green House : Part 1 - (Really Similar) Building a High Tunnel Hoop House / Green House : Part 3 - (Really Similar) Dampening Off! - (Interesting) Gators and Greenhouses and Greenbacks, ohh my! - (Interesting) Building a High Tunnel Hoop House / Green House : Part 3 BY ANDY, O N M AY 3R D, 201 1 Plastic cover ready!We finally had enough of a break in the wind and weather around here to do the last of the work on the hoop house / high tunnel. That “last of the work” would be to install the plastic. A quick search of the web on how to install greenhouseplastic didn’t really offer a lot of suggestions or help. Further more we knew we were going to be inflating the two layers of plastic with a greenhouse inflation blower… and that too isn’t well documented out there. So – here’s the tools, techniques and lessons we learned in the last phase of constructing this greenhouse.
Wiggle wire First, we decided that the easiest way to attach the plastic was using a wiggle wire system like most commercial greenhouses. The wiggle wire is a bent piece of stainless steel wire that fits inside a specially designed aluminum channel – the wire presses and pulls on the plastic and the channel follows the contour of thegreenhouse. The idea is to basically close the plastic over the structure on 4 sides kinda like a big 4 sided Ziplock bag thenpump air into the space between the plastic to create a layer of insulation and keep the plastic taunt so the wind can’t grab a hold of it and rip it off. Pretty simple system that goes together pretty fast. time will tell how it handles the winds we get up here! How do you get plastic on a greenhouse? The long side That question was one we couldn’t get a really good answer on. We waited for a calm day (no wind) and then pulled the plastic layers over the hoops. The inner layer is a infrared reflective layer to keep the heat in at night and the outer layeris typical greenhouse plastic. Once it’s draped over the structure we picked a corner and started working from there. The general approach is to close things up like a plastic bag… starting at one side and working our way around. By doing things like that the plastic can shift and slide as we pull on it and we can minimize wrinkles in the final layout. So, we started on one of the longest sides by installing the wiggle wire the entire length. From there we then went up along the end hoop. The only place s the plastic is attached is on the long bottoms and thenalong the contour of the end hoop (again – so the entire greenhouse can be inflated). The process works best with at least 2 people, we could have easily used a third. One person pulls on the plastic to ensure it’s tight and the other person installs the wiggle wire. (Kelli will tell you the worst job is the hand cramps you get for pulling so hard on something as slippery as plastic – I might tell you the worst job is mashing your fingertips over and over with the wiggle wire in the channels… honestly, neither job is horrible - but also not something you look forward to repeating!)
Inflator - go! With the plastic secured along almost the entire greenhouse, we left the corner where the inflator gets installed unattached just enough so I could worm my way in-between the 2 layers of plastic and cut a hole through the inner layer. In this picture you can see the white dot looking thing – that’s the diffuser that the inflator motor blows through. It sitesbetween the 2 layers of plastic and keeps the space pressurized. One thing I decided to do as an added precaution was to place a piece of 4″ wide greenhouse tape over the spot where I cut the hole. That should help keep this area for developing any stress tears over time as the wind punishes the structure. Yup - its inflated. After the inflator fan was installed we finished installing the last of the wiggle wire in that corner and trimmed off theexcess plastic. We then fired up the fan and let the greenhouse puff up. It was an impressive site to see as the wrinkles all disappeared and the plastic shell became a component of the structural support for the building. Very impressivedesign. We have noticed that our blower seems to be a little “over active” and we have ordered a control switch to dial in the perfect amount of “inflation”. All in all without a final tally of the receipts the project came in a little more than we thought it would (don’t they all) BUTthe structure is a LOT more substantial than we expected and are pretty optimistic that it will sustain the big winds we get. Total price tag including all the mistakes and the bender we will have for years : around $1500. So given it’s size, that’slike $4.46 a square foot of protected, sun warmed space (not to bad) We also learned a TON in doing this, knowledge that would have been REALLY expensive to acquire on a full fledged kit. Actually – after we finished it we both looked at the space next to it where the bales of hay sit and discussed how long the next one will be. :) The last thing we have left to do is attach the last little rolled up plastic that is along the hooped ends to the faces. It’s a small job (just not done). We also learned several things we would differently next time. Big doors on both ends. Translucent panels on the ends. Grade the area where it will be constructed first (building this OVER the low tunnel was stupid and caused things to bemuch more difficult than they needed to be). Install water hydrant inside the house for easy water access. I’m sure therewill be other lessons learned too – but in the end – we are REALLY, REALLY happy with our homemade greenhouse! (for a few more pictures visit our Flickr Photostream)The plants that have been moved inside the new greenhouse seem to like it – but they are not very vocal anyhow… Stay tuned for a tour of the inside…
Our first homemade greenhouse If you liked this post, check out these: Building a High Tunnel Hoop House / Green House : Part 1 - (Really Similar) Building a High Tunnel Hoop House / Green House : Part 2 - (Really Similar) Dampening Off! - (Interesting) Gators and Greenhouses and Greenbacks, ohh my! - (Interesting)Part I Site Planning and Construction Article Constructing a Simple PVC High Tunnel by Jim Hail, Robbins Hail, Katherine Kelly, and Ted Carey Introduction This low-cost, 30’ long by 18’ wide high tunnel is constructed using PVC pipe for hoops. The materials cost roughly $500 (including shade cloth for summer production) LINK: and we didnt shop for the best buy on materials and lumber. A slight disadvantage of How to Build a High the design is that curvature of the hoops may allow rain to run inside the edge of the Tunnel house when the sides are raised for ventilation. One person can complete most of the by Amanda Ferguson, construction, but inserting the hoops and putting on the plastic requires at least two University of people. Also, it is nice to have someone to share the heavy work of driving in the Kentucky ground posts. A crew of four can easily construct a high tunnel of this design in a single day.
The dimensions of this high tunnel design may be scaled-down if you have limitedspace available for your high tunnel. At a lesser diameter, or in well-protected locations,it may be possible to use 1” PVC for the hoops, with 1½” PVC for the posts. The lengthof pipe to use for hoops may be calculated using the formula for the circumference of a LINK:circle, (3.14)r, where r is half the width of your tunnel. Add 3’ to insert into the ground Hoop House Constructionposts. for New Mexico: 12ft PVC will react with the polyethylene greenhouse covering, so in order to attain the X 40ft Hoopexpected 4-year life span of the plastic, measures should be taken to prevent contact Housebetween the PVC and the polyethylene covering. This may be done by painting ortaping the side of the PVC hoops that will be in contact with the plastic. Having saidthat, the oldest high tunnel at Bear Creek Farm in Osceola, Missouri, is eight years oldand is still covered by its original plastic, which is in contact with the PVC hoops. Note: Our procedure calls for driving 3’-long PVC posts into the ground after layingout the baseboards. We have found this to be a convenient way to proceed. However,in shallow, tight or stony soils, it may be necessary to dig holes using an augur, andthen set the posts in concrete. If it is likely that you will need to do this, then postsshould be set before laying out the baseboards.Materials
Material Dimension Quantity NotesTwine & Pegs For corner and baseboard layout. For baseboards. The boards will be in contact with the soil, so you might consider a rot resistant wood, such as cedar or redwood. If you will be growingLumber 2" x 6" x 10’ 6 food crops in the tunnel, it’s probably best not to use treated lumber because of possible health concerns. 1" x 4" x 10’ 6 For hip boards. Lumber for attaching baseboards, bracing end 2” x 4” x 8 18 hoop, and framing end-walls. Lumber for framing doors. Depending on door size, 2” x 4” x 10 4 amount of bracing desired amount may vary. We put a 32”-wide door on each end. For attaching plastic to hip boards and end-walls. Poly tape may also be used for attaching plastic toFurring strips 1" x 2" x 10’ 12 end walls. Wiggle wire is a more costly but convenient method for attaching plastic to hip boards.Schedule 40 1½” x 20’ 12 For 11 hoops + purlin.PVC pipe bell-end 10’ x 1½” 12 For 11 hoops + purlin. straight-end 3’ pieces of 22 For ground posts. Requires 8 10 pieces 2”Primer & Glue . . For connecting PVC pipe For attaching hoops and posts to baseboards, andCarriage bolts 4½” x ¼” 33 hoops to purlin – purchase bolts, washers and nuts.Deck screws 1½” 1 lb 2½” 2 lb 3½” 2 lbChain link 31 2 For roll up sides.fence top railPVC fittings 1” . To make handles for roll up sides.Self-tapping For connecting top rail pieces, and for attaching . . PVC handle to roll-up side.screws For covering the house use 6 mil UV stabilized. ForGreenhouse the end walls, you may use a lighter gauge material, 30’ x 34’ 1 since it may be taken off each summer to enhancepolyethylene ventilation. White 38% shade cloth with grommets sewn everyShade cloth 30’ x 25’ 1 3’.Tools
Step ladderLevel and plumb lineStapler and staplesSledge hammer for driving baseboard stakes and PVC ground postsSaw for cutting lumber and PVCDrill with screwdriver bit, and with extended ¼” wooden drill bit for drilling holes forcarriage boltsSite Preparation and Construction1. Site Preparation. Choose a good site for locating the tunnel with respect to light,drainage, access, irrigation, etc. Prior to beginning construction you may wish to build aslightly elevated, level pad, or take other measures to ensure that run-off water will notflood the high tunnel, particularly in the winter. Orientation with respect to wind is notcritical, but we have oriented ours east west, meaning that prevailing winds are usuallyfrom the sides.2. High Tunnel Layout. Mark the corners of a rectangular area 18’ wide by 30’ long.Make corners square by ensuring an equal distance between perpendicular corners(should be 35’ between outer corners of pegs). Drive 2”x2” peg into the ground at thecorners and stretch twine around the outsides of the corner posts where baseboardswill run. It is not essential for the tunnel to be level, but this certainly helps to makedoors square. To layout a level tunnel, use a level to adjust the height of the string to beused as a guide for baseboard placement. We have built ours on slight slopes, with thebaseboards following the slope, and hip boards parallel to the baseboards.3. Set Baseboards. Cut 14 2’ pieces of 2”x4”, and cut points on ends for driving intothe ground. Drive in these stakes for baseboard attachment on the inside of the guidestring, orienting the broad side of the 2”x4” parallel to the string. For the long sides ofthe tunnel, posts should be 10’ from each end (where the baseboards will meet) and 6”from the ends (to allow space for PVC ground posts). Attach the 2”x6”x10’ sidebaseboards to the pegs using 3½” screws, starting at one end (snug with the cornerpeg). For the end walls, place a peg 10’ from the outer edge of one of the sideboards,and 6” from each of the corners. Attach the first 2”x6”x10’ (snug against the end of thesidewall baseboard) and cut the second one to fit.
Figure 1. Baseboards laid-out ready for ground post installation.4. Drive in Ground Posts. Mark inside of side baseboards at 3’ spacing starting fromthe end of the sidewall baseboard. Remove corner pegs and string and drive in PVCground posts at corners and at 3’ marks. Posts should go in roughly to the top of thebaseboard, at most. It is possible to damage the PVC by hitting it too hard with thesledgehammer, or trying to force it through tight or stony soil. To avoid damaging PVCwith the sledgehammer, have a helper hold a length of 2”x4” over the end of the pipe,and pound on the 2”x4”. The helper should wear gloves to protect against jolts.Note: Our procedure calls for driving 3 PVC posts into the ground after laying out thebaseboards. However, in shallow, tight or stony soils, it may be necessary to dig holeusing an augur, and then set the posts in concrete. If it is likely that you will need to dothis, then posts should be set before laying out the baseboards.Figure 2. Ground posts ready to be driven in.
Figure 3. Ground posts damaged during pounding. This can be prevented by pounding on a 2"x4" ratherthen directly on the PVC pipe.5. Hoop Assembly. Assemble 30’ hoops and purlin by gluing together 10’ and 20’ PVCpipes. Use PVC primer and glue, following instructions for correct use of products.Figure 4. Hoops being placed in ground posts.6. Raising Hoops. Erect hoops by inserting one end into a 2” PVC ground post, andbending the hoop to insert into the ground post opposite on the other side of the tunnel.Make sure that ends of hoops extend well into the ground posts (at least 12”). Afterinserting the posts, make minor adjustments in the height of the hoops (sight along thetop of the hoops from a ladder) so that all are at the same height. Drill throughbaseboard and pipes with ¼” wooden drill bit. Attach using carriage bolts, washers andnuts, pushing the bolt through from the outside, and tightening the hoops snug to thebaseboard
Figure 5. Drilling through baseboard, ground post and hoop. Carriage bolts will hold hoop in place.7. Purlin Attachment. Attach purlin (30 1½ PVC pipe) to the inside of the hoops. Drillthrough purlin and hoops at 3’ spacing, and attach using carriage bolts, washers andnuts. Head of the bolt should be up to present a smooth surface to the poly that willcover the tunnel. We put a piece of duct tape over the top of the carriage bolt beforeputting the poly on the hoops.Figure 6. Tunnel with purlin and hip board in place.8. Hip Board Attachment. Attach hip boards at 3’ height using 1½” screws. Markhoops 3’ above baseboard, and attach 1”x4”x10’s end to end, starting at one end of thetunnel. Ends of hip boards may be secured together where they meet by screwing ablock of wood across the inside of the junction.
Figure 7. Hip board in place.9. End wall Construction. Use 2”x4” lumber to frame in end walls. There is no hardand fast rule for end wall design. However the attached picture shows our generaldesign consisting of four uprights reinforced by horizontal and diagonal bracing.Spacing door uprights at a standard distance (32”, 34” or 36”) accommodates standarddoor sizes. Cut notches in the uprights to fit the inside of the baseboard or the hoop,and attach using 2½” or 3½” screws.Figure 8. Tunnel showing end wall design at K-State Research and Extension Center, Olathe, Kansas.
Figure 9. Tunnel showing end wall design at Full Circle Farm, Kansas City, Kansas.10. End wall Bracing. Attach end wall bracing. Cut 2”x4” lumber to run from baseboardclose to the second hoop, and attach to end wall and baseboard.11. Plastic Preparation. Attach furring strips end to end along the upper half to the hipboards. Alternatively attach the channel for wiggle wire using self tapping screws.12. Plastic Attachment. It is best to do this on a calm day. Lay out the poly lengthwiseon one side of the high tunnel. If you are cutting from a longer roll of plastic, be sure toleave 2’ extra on each end to allow for attaching to the end walls. Pull plastic over thetunnel. A simple way to do this is to secure a rope close to the edge of the poly at eachend of the tunnel by placing an object such as a tennis ball under the plastic and tyingthe rope around it through the plastic. Then the rope is thrown over the tunnel and theplastic pulled over the tunnel using the rope. Make sure the plastic is well centered onthe tunnel and then attach by placing furring strips over the plastic, snug against andjust below the furring strips already attached to the hip board. Attach the furring stripswith 1½” screws, placed every 2 or 3 feet. Pull the plastic tight and attach to the otherside in the same way. Finish securing the plastic by attaching to the end walls usingadditional furring strips. Note, you may also use poly tack strips (commerciallyavailable).Figure 10. Poly attachment to hip board using one furring strip. This method is less secure than otherssince poly tends to tear at the screws.
Figure 11. Picture showing the 2-furring strip method of attaching poly to the hip board.13. Roll-up Side Installation. Attach roll-up sides. Assemble top rail pieces to roll upsidewall plastic with. Make sure the pipe is longer than the tunnel on both ends so thatyou can attach a handle to it, and to avoid difficulties with rolling up sides. Attach thepipe to the poly. We have used duct tape for this, but a better option is to use specialclips for attaching poly to pipe, which are available from commercial sources. Analternative is not have roll-up sides at all, but to simply tie up poly when ventilation isrequired. This is easily done by placing eye-hooks in the hip board at each hoop, andrunning a piece of string below the sidewall poly, around the hoop and back. Both endsof the string are tied to the eye-hook. For roll-up sides, various options are possible,figure 8 shows a PVC crank that we have used.Figure 12. Poly attachment to hip board using wiggle wire.
14. Stabilize Sidewalls. Prevent sidewalls from billowing. To prevent sidewalls fromflapping in the breeze, some sort of support is needed to help keep them in check.Pieces of used drip tape running from the hip board to the baseboard at each hoop iseffective for us. Using a fender washer along with the screw prevents screws fromtearing though the drip tape in high windsFigure 13. A drip tape strip from hip board to base board at each hoop can keep side walls frombillowing.15. Install plastic on the end walls. Since we take off the end wall plastic during thesummer months, we use a lower thickness end wall plastic. Either commercially For more on suppliers goavailable poly tack strip or furring strips may be used to secure a sheet of plastic to: Resourcescompletely over the end wall. Then a hole may be cut for the doorway.16. Frame Door. You can make a door, or use an old door on one or both ends of thetunnel.17. Shade Cloth Installation. Shade cloth helps keep temperature down during thesummer in high tunnels. In hot years, we put ours on from Memorial Day to Labor Day.Grommets sewn into the cloth every three feet allow for tying down to eye hooks fixedinto the baseboards. We skew the shade cloth toward the south in order to providebetter shading on that side.About the AuthorsRobbins and Jim Hail own and operate Bear Creek Farm in Osceola, Missouri.
Katherine Kelly owns and operates Full Circle Farm in Kansas City, Kansas.Katherine Kelly in her newly constructed hoop house.Ted Carey, Extension Specialist Food Crops, Kansas State Research and ExtensionCenter Olathe, Kansas. Building the KSU high tunnel High tunnels are unheated greenhouses used to extend the growing season. In Kentucky they can allow year-round vegetable production. In 2005-06 we erected a 30 x 40 high tunnel at the Kentucky State University research farm, using a frame salvaged from a heated greenhouse. The following pictures show the construction process. A table showing the cost of materials is at the bottom of the page. Click a picture to see a larger view. Click here for a detailed examination of the effect of this tunnel on microclimate.
September 6, 2005 September 7, 2005Untreated 2x4s were A screen door frame was built to fit inside metal hoops salvaged from a usedpainted to protect the end heated greenhouse.wall framing studs. Organicstandards do not allowtreated wood to come incontact with the soil orcrop. September 8, 2005 September 13, 2005End walls included 4 x 4 Metal hoops were screwed to each end wall, then aluminum wiggle wire track waswindow frames. attached to the upper edge of each hoop with metal screws.
September 13, 2005 September 13, 2005The summer cover crop of Anchors of galvanized steel pipe, welded to angle iron, were pounded 2 into thecow peas was incorporated soil to support each end wall.into the soil at theconstruction site. Cowpeaswere chosen as a heattolerant cover crop thatwould add nitrogen andorganic matter to the soil. September 13, 2005 September 15, 2005End wall frame struts were Workshop participants at the KSU farm field day attached interior hoops to anchorbolted to the anchor posts. pipes. Anchor pipes had been pounded at an angle, with a wooden block between the pipe and sledge hammmer to prevent the pipe end from splaying.
September 24, 2005 September 24, 2005Completed tunnel frame. Frame structural details. Top: End wall struts supported by angle iron and anchor pipe. Bottom: Pipes joined by brackets (left) and sleeves (right). December 7, 2005 December 7, 2005Recycled plastic 1x6 toe A 60 W blower fan was attached to a hoop, and through the inner plastic layer.boards were attached Hoses were attached at the corners of the house to allow air to pass between thearound the house side walls and end walls.perimeter. A strip of 2x2ran the length of the house,2 above the soil surface.Aluminum wiggle wire wasscrewed to the end wall toeboards and the side wall2x2. Two layers of 6 milplastic were draped overthe frame, and attached tothe end hoops with wigglewire.
December 7, 2005 December 7, 2005Two layers of end wall Attaching plastic to the frame took about three hours on a calm afternoon.plastic were attached withwiggle wire (foreground). January 18, 2006 January 25, 2006An 8 wide paving stone pad Six-week-old lettuce and kale seedlings were transplanted on one-foot centers.was laid atop gravel andsand at one end of thehouse. An 18" wide pathwas constructed down thecenter of the house.
Feather meal fertilizer(Nature Safe, 10-2-8) wasincorporated into the soilwith a roto-tiller at 100 lbsN per acre, and three bedswere formed on each sideof the center path. January 27, 2006 March 2, 2006Lettuce, beets, radish, and Right bed: Transplanted kale (foreground) and lettuce (background). Left bed:spinach were direct-seeded. Direct-seeded greens.
March 21, 2006 February 2006 - June 2007Ready for harvest! Left bed: Temperatures inside and outside the high tunnel.Transplanted lettuce(foreground) and kale(background). Right bed:Direct-seeded greens.
Cost of high tunnel materials Expected life ¢ per square Material Cost $ per year (years) foot per yearSalvaged hoops $1,020 20 $51.00 4.3¢ (estimated value)Wiggle wire & track $250 20 $12.50 1.0¢Paving stones $380 20 $19.00 1.6¢Plastic boards $300 10 $30.00 2.5¢Screen doors $250 10 $12.50 1.0¢Lumber $160 10 $16.00 1.3¢Fasteners $60 10 $6.00 0.5¢Paint $30 10 $3.00 0.3¢Fan $100 10 $10.00 0.8¢Plastic $660 4 $165.00 13.8¢ Total $3,210 $325.00 27.1¢The plastic accounted for only 20% of the up-front cost, but will account for more than half ofthe cost amortized over time. The value of crops harvested should exceed the up-front materialcost in the first year.