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Starting Plants Early Outdoors - New Mexico State University


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Starting Plants Early Outdoors - New Mexico State University

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Starting Plants Early Outdoors - New Mexico State University

  1. 1. Starting Plants Early Outdoors Guide H-220 Revised by Curtis Smith1 Cooperative Extension Service • College of Agriculture and Home Economics This publication is scheduled to be updated and reissued 6/13.An early start, an important factor to both home Mulches, other than plastic films, tend to keepand market gardeners, can be attained by several soil cooler. This is due to the insulating qualities ofmethods. Some may not be practical on a large mulch and the fact that the sun does not reach thescale, but they could provide the hobbyist with soil itself.ample rewards. Placement of seed in the south side of east–west The most important factor to remember when beds tends to promote faster early growth, as theattempting to get a jump on the weather is that sun warms up soil on the south exposure faster.plants must be gradually exposed to an unprotectedenvironment. Shading and watering become im-portant tools in the “hardening” of these plants. Peat pots, peat pellets, and seed flats can be Plant protectionseeded and plants started indoors. However, space There are a number of techniques for protectingmay become limited very quickly in an active seed and young plants from the cold and the wind.household, making it more practical to start plants Cold frames provide protection from moder-outdoors. ately cold temperatures. They trap solar energy ef- ficiently when properly oriented, but will require ventilation when the outside temperatures warm.Early growth A cold frame is a box-like structure (Figure 1)There are several things that one may do to hasten with a sloping cover (lid) which may be hinged togrowth of plants during periods when the ambient make ventilation easy if a day gets too hot. Thetemperature is somewhat lower than most plants sloping cover should have a south, southwest, orrequire. west exposure to trap as much solar energy as pos- Variety selection is important, as some do bet- sible. The difference in height from back to frontter than others during cool weather. For example, should be between three and four inches for eachshort-season sweet corn (early cultivars) grows bet- foot of distances between them.ter than mid- or late-season corn. Frost-tolerant Ample drainage is required in these structures tocole crops may be started even earlier. minimize diseases. Drainage is provided by layers of Fertilizer, when properly placed in sufficient coarse material, such as gravel and sand.quantities, can help in promoting early, vigorous Glass or non-opaque plastic films may be usedgrowth. for the cover. Plastic films, even though they will Irrigation plays an important part. Moist need replacing often, are recommended becausesurfaces tend to be cooler than dry ones, due to they do not break as easily. Cold frames need notevaporation; however, drip irrigation seems to result be permanent fixtures. Temporary cold frames overin faster growth. It is a good idea to irrigate with flower beds can be used efficiently to start plantsplenty of water but less frequently, and to avoid early for spring transplanting.sprinkling, which cools the soil even more.1 Extension Horticulture Specialist, Department of Extension Plant Sciences, New Mexico State University, Las Cruces.To find more resources for your business, home, or family, visit the College of Agriculture and Home Economics on theWorld Wide Web at
  2. 2. Hot beds are designed in the same way as coldframes except that a source of heat is added. Heating cables (available through seed catalogs)buried in the soil medium can be used successfully.Caution—Place a layer of hardware cloth over theheat cable to prevent electric shock when digging inthe hot bed. Manure hot beds have been used for a long time.Heating is provided by the decomposing material.A 12- to 24-inch layer of manure should be placeddeeply enough in the bed to leave room for an 8- to12-inch layer of growing medium on top (Figure2). Over time the manure will lose its heating quali-ties and need to be replaced. Fresh, not composted,manure should be used. Horse manure, due to itshigh proportion of straw, is better for this purpose.Ventilation may be necessary to prevent extremeheat build-up within the structure. Hot caps and walls o’ water are small, green-house-like conical devices for protecting individualplants. They are made of translucent paper or plas-tic film fused to form a ring of water-filled tubes.They must be anchored to the ground. The weightof the water in the wall o’ water helps hold themin place. Since they are fairly low, 12–18 inches,plants will outgrow them. Ventilation may be an-other problem. The hot caps may be torn and thewalls o’ water may be opened from conical to cylin-drical shape to provide ventilation. Both items areavailable through seed catalogs and many nurseries. Guide H-220 • Page 2
  3. 3. Greenhouse-like structures (tunnel cloches) fabric may be used to cover these structures. Clearcan be easily made with wire loops forming a semi- plastic will capture more heat, but may above ground and covered with non-opaque White plastic will gain less heat, but will help pre-plastic films (Figure 4). The plastic needs to be vent frost damage and is less likely to overheat. Rowanchored to the ground by piling soil on the edges cover fabric will provide even less heat gain, but stillor by some other means. The ends should be re- protects against late frosts. The ends of the growingmovable to provide ventilation when needed. Clear, structure may be closed on cold nights and openedtranslucent white plastic or spun-bonded row cover during the day to allow ventilation. Black-plastic mulch is a film 4 to 6 mils (1 mil = lems will be minimized, since light reaches only the1/1000 in.) thick that can be used to give seedlings an germinating seedlings (near the planting holes). Clearearly start. The film is placed on top of the prepared plastic will more rapidly heat the soil by allowingseed bed and anchored on the sides (Figure 5). Water sunlight to heat the soil directly, but will not providewill infiltrate from the furrow into the seed area. Seeds weed control benefits. Both will conserve moisture.or transplants are placed in the soil through holes When the air temperature gets high, the soil could getmade in the plastic. Since the film is black it will ab- too hot unless straw or some other type of mulch issorb solar energy and heat the soil beneath. Another placed on top. Plastic does not readily decompose andbenefit of the black plastic mulch is that weed prob- must be removed, unless it is biodegradable.Figure 5. Black-plastic mulch. Guide H-220 • Page 3
  4. 4. Inner tubes, when filled with water, will trapsolar energy and release heat during the night,thereby offering some protection. The plant orplants are grown in the soil within the hole of theinner tub (Figure 6). It is removed when tempera-tures are no longer cold enough to be detrimentalto plants. Covering with plastic or other materialon cold nights will increase the protection fromfreeze damage. One-gallon plastic jugs may be used if thebottom is cut off and the container is pushedinto the soil far enough to avoid blowing over(Figure 7). The cover may be removed if someventilation is needed. Holes in the ground can be used to start plants ed and the holes filled (Figure 8). Not many plantssuch as tomatoes. They may be covered with plastic thrive under these conditions; however, tomatoesor other transparent material to allow light to reach do very well.the plant. As the plants grow, soil needs to be add-Original author: Esteban Herrera, former Extension HorticulturistNew Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Departmentof Agriculture cooperating.Revised June 2008 Las Cruces, NM Guide H-220 • Page 4