What is season extension? Increasing the growing season at either end, spring and/or fall
Why try to extend theseason? Allow more time for crops to mature Grow different varieties Move toward year-round production and income potential Fresh greens in the winter
Frost-free period We’ll define the length of a frost- free period as the number of days between the date of the last 32°F temperature in the spring and the date of the first 32°F temperature in the fall.
What’s “freezing”? The National Weather Service defines a “freeze” as occurring “when the surface air temperature is 32°F or below over a widespread area for a climatologically significant period of time (greater than one hour).” (U.S. Department of Commerce, 2005)
How long are our frost-free periods? Lots of variation among periods for the last 100 years Some years have had frost-free periods of over 150 days (approximately 5 months) Other years have had frost-free periods of less than 90 days. (Reno data) KEY: lots of varibility, so you have to watch the weather predictions!
Do frost-free periods everchange? For the 30-year period of 1971-2000, the average date of the last 32° temperature in the spring was May 21 while the date of first 32° temperature in the autumn was October 3 (134 days).
1991-2005 The date of last 32° reading was May 3, and the date of first 32° reading in the autumn was October 19 The average length of the frost- free period grew from 134 days (for 1971-2000) to 168 days for the more recent 15-year period This is an increase of a full month!
Hard freeze A hard freeze is sometimes defined as occurring on a date when the temperature drops to 28°F But…you can expect damage when temps drop to 32°F
City Frost-Free Days Carson City 90 - 116 Elko 57 - 87 Ely 53 - 81 Fallon 106 - 131 Lovelock 111 - 140 Reno 85 - 125 Tonopah 107 - 147 Winnemucca 75 - 107Based on historical data indicating 90% (first number)- 121 Yerington with temperatures above50% (second number) 82 to 32°F.probability of consecutive dayshttp://www.wrcc.dri.edu/summary/Climsmnv.html
Cold damage Plants lose heat faster than the air! Anything that reflects the radiating heat back down will prevent or at least greatly reduce frost formation (for example, clouds)
Season Extension:Start with cultural practices Site selection and microclimates Soil and moisture content Windbreaks and shade Irrigation Cultivar selection Transplants
Take advantage ofmicroclimates Some areas around your property warm up faster in the spring, stay cooler or warmer in the summer, or are protected from the wind South-facing slopes will be warmer Cold air settles into valleys
Site selection #1: Hours of sunlight Prevailing winds
Windbreaks and shade • At right angles to prevailin g winter winds • Consider effect on sunlight
Shade fabric Creates a cooler microclimate to help prevent bolting and bitterness Faster germination of cool-weather fall crops Shading 30 -50% in midsummer can lower leaf temps by 10 degrees or more
Managing moisture Plants under drought stress can be more susceptible to cold damage Water holds warmth and releases it slowly So…water before frost is expected
Alter soil temperatures Use clear plastic mulch to warm soil in spring and retain extra heat in fall Cover the edges of the plastic with soil to anchor it in place Temps increase by 8 to 14 degrees to a depth of 2 inches and 6 to 9 degrees to a depth of 4 inches
Mulch to insulate plantsOrganic mulches such as straw alsodecrease radiated heat and conservemoisture, preventing cold (and hot)extremes
Choose hardy crops Start and end with cold-hardy vegetables that tolerate frost Look for short-season varieties Other varieties are specially adapted to growing in long, hot days, extending your growing season into the summer (ex. slow bolting lettuces) Read seed packets and catalog descriptions
Spring crop transplants Start plants early Start seeds of tomatoes, peppers, and eggplants 8 weeks early Start seeds of cole crops about 4 to 6 weeks early Start vine crops 1 week early
Fall crop transplants Start plants for late-season crops in late summer Seed a second season of quick- maturing vegetables, such as snap beans, peas, greens, radishes, cole crops, and turnips later in the season Grow cold-tolerant species in the fall
Examples of late-seasoncrops Kale Collards Lettuce Spinach Mustard greens Arugula Broccoli Broccoli rabe Mache Beets Lettuce, kale and rabe Peas
Winter harvest Decreasing levels of light in fall/winter slow plant growth to near-dormancy Lowest light in December and January Many cold-weather crops must be harvested by the end of fall
Vegetable planting dates Planting dates depend upon the plant cold-hardiness. Semi-hardy vegetables can be planted two to four weeks before the average last killing frost date of May 15, or in cool fall temps
Vegetable planting dates Plant frost-tender and cold- sensitive vegetables after the last frost date Buy transplants, or start from seed indoors from mid-March through mid-April Earlier transplanting can be done when hotcaps, row covers or other protection is used
More tips Grow cold- tender herbs, dwarf fruit trees, etc. in containers that you can move indoors
Protect from early and late frosts Cover early and late season plantings with mini-greenhouses made from clear plastic, old window sashes set on hay bales, or fabric row covers Vent the covers on warm days to prevent excessive heat buildup
• Use hot caps in spring• Need to vent them• Works for small plants• Blocks some light
Light penetration not good; minimal frost protection
Walls of Water Good frostprotection but expensive
Fall freeze protection Use old sheets, blankets, draperies, etc. Cover plants before sundown to trap heat
Fall freeze protection Extend the covering all the way to the ground so cold air can’t seep in Put in place before sundown Especially useful for the first few frosts when warmer weather is then expected
More tips Cover hardy root crops with a 6- to 12-inch-thick layer of straw or other organic mulch in fall to prevent the soil from freezing. Harvest as needed throughout the winter.
Row covers •Agribon, Reemay, Harvest Guard, etc. •Come in different weights Can provide 3to 5 degrees offrost protection
Row covers Warm and speed the growth of seedlings in spring Slow the evaporation of soil moisture Protect plants from wind, heavy rain, and hail Heavier fabrics provide more frost protection but block more light
Row covers Keep pests off plants but need to remove covers for insect pollination Protect late summer crops from fall frost Protect crops from hot temperatures and burning sun rays Must anchor with soil, wood, rocks, etc.
Cold frames Can provide 5 – 7 degrees of protection Can be used in the spring to start plants or in the fall for cold-hardy crops Use old windows or glass doors to make your own No standard size; keep width narrow enough that you can easily reach across
Can add black containersfilled with water to store heat for the night
Cold frames Don’t use wood treated with preservatives! Slope the lid to the south Place on south side of house
Cold frames Provide for ventilation of excess heat when temps rise above 55 degrees Cover to protect against freezing, or stack straw bales against the frame
Cold frame tips Ventilate on warm days Checktemperatures with a thermometer Protectduring freezing weather: Remember that cold frames give only 5-10 degrees of warmth.
More cold frame tips Water: make sure plants aren’t getting too much or too little water. Hardening plants: open the lid of your cold frame longer and longer each day
Benefits of low tunnels About five to six weeks earlier production in the spring Several weeks later production in the fall Some protection from insects and foraging animals Some protection from extreme weather conditions, such as strong winds, hail or frost http://simplegoodandtasty.com/2010/05/25/tunnel-farming
Tips for low tunnels Use UV-stabilized tubing Don’t expect protection from hard freezes Plan for access and ventilation
Building materials to construct one minitunnel for 40-inch by 30-foot raised bedQuantity Item Description Unit Price Total200 feet 1/4-inch nylon rope $0.08/ft $16.001,8-ft by 38- 6-mil greenhouse poly $0.13/sq $39.52ft sheet film ft 1/2-inch sch 40 PVC80 foot $0.22/ft $17.60 pipe20 foot 1-inch sch 40 PVC pipe$0.44/ft $8.8044 2-inch wood screw $0.05 $2.202 3/8-inch by 2-foot rebar $0.75 $1.502 Eye screw $0.50 $1.00*Prices may vary depending on Total $86.62location, etc.http://www.noble.org/Ag/Horticulture/RaisedBedGardening/mini_tunnel.html
High tunnels (aka hoophouses) Big enough to walk into Size them to meet your needs Plant in-ground or in raised beds Does not have an added source of heat or ventilation Can extend the season through the winter by up to three zones, or a month in the fall
Orient in an east-west direction tomaximize sunlight, but also consider
Structural elements Can be mobile or fixed in place End walls are most important to strength Can incorporate an opening for ventilation in the end walls Hoops no more than 4 feet apart Peaked-roof (vs. U shape) stronger in snowy climates
Structural elements Use a center support to increase stability Use 6-mil, greenhouse-grade, UV stabilized polyethylene Roll-up sides allow for ventilation
How to Build a High Tunnel (video)http://www.youtube.com/watch?v=am1Tso2l3kcAlso seehttp://www.extension.org/pages/18356/low-cost-high-tunnel-construction
Minnesota study On average, tunnel vegetables such as lettuce, tomatoes and cucumbers were harvested about six weeks earlier than those grown in the open, while peppers were ready nearly ten weeks ahead. Many of the tunnel plants produced as much as double the output of the outdoor crops
What about winds? High tunnels placed perpendicular to prevailing winds typically receive the most damage, so consider placing parallel The best protection against uplift is to ensure that posts are driven at least 24 inches into the ground Use stretch cord over the top of the plastic from one side to the other, every fourth rib
What about snow? A high tunnel built from ribs of 20 foot pipe bent to create a 14 foot wide X 6 foot high structure will withstand only about 10 psf This is about 2 inches of water as snow Might be as little as one foot of snow
More tips for dealing with snow Use a center roof rib Orient the structure so prevailing winds blow the snow off the high tunnel Remove the plastic in the winter if not under production Brush off snow using a long-handled broom (carefully!)
NRCS High Tunnel PilotProjectEligibility Requirements: To qualify, the applicant must: ◦ be an agricultural producer ◦ install the high tunnel(s) on cultivated land which includes existing gardens, irrigated hayland and irrigated pasture ◦ have raised or sold $1,000 worth of agricultural products http://www.nv.nrcs.usda.gov/programs /NV_high_tunnels.html
GreenhousesWalk-in, permanently placed The most expensive solution Usually have venting and heating systems (requires energy inputs but gives more control) In some areas, can be used year round Can add mass for thermal storage (water barrels, etc.)
Do your homework Many types on the market Many plans available as well Look at the alternatives before investing Can use to insulate your house when attached Consider a solar greenhouse
GreenhousesWalk-in, movable Less expensive Can be disassembled and stored away when not in use Usually used one to two months before the last frost in the spring.
Whatever you do… Keep good records! Consider a journal that includes varieties, dates planted, dates matured, freezes, etc. Nurture your soil with lots of organic amendments Keep a map of what was planted where
Why rotate crops? Breaks the cycle of disease and pests Helps to maintain adequate nutrients Can help improve soil structure (alternate deep-rooted plants with shallow-rooted plants) Can decrease costs
Considerations in crop rotationschemes Heavy feeders: leafy veggies, brassicas, corn Soil conserving/improving: legumes (peas and beans) Lighter feeders: bulb and root crops, many herbs
Another simple rotation Root Legumes crops, and onions brassicas Sweet Nightshades corn, - cucurbits tomatoes and peppers
End-of-season maintenance Clean up! Remove dead vegetation and windfalls, compost healthy material. Remove fallen fruit and dead leaves to decrease pest problems. Think about cover crops to enrich and stabilize soil (winter rye, triticale)
End-of-season maintenance Enrich garden beds with compost or manure; add mulch or leaves; think about nutrient needs for your specific crops Collect dried seed from open pollinated flowers & veggies Clean out cold frames for winter use
End-of-season maintenance Clean and oil lawnmower, other garden equipment and tools before storing for winter Take equipment in to be sharpened (mower blades, pruning equipment) Drain and store hoses carefully to avoid damage from freezing Clean, sand and oil garden tools before storing them for the winter