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The Art of Season ExtendingTHE ART OF SEASON EXTENDING With the creative use of season extenders, it is possible for growers of all sizes to lengthen their growing seasons by days, weeks or months. Providing soil warmth and frost protection increases yields by allowing earlier planting and/or later harvest. Cooling and shading with shade cloth, on the other hand, can extend the production or enhance the flavor of heat-sensitive plants. Season extenders can also be a valuable pest management tool by establishing your plants before the onset of pest insects (such as aphids, thrips, whiteflies, flea beetles, cucumber beetles, lygus bugs, Japanese beetles and Colorado potato beetles), reducing plant stress caused by temperature swings, and providing a timely barrier against damage by mice, deer, rabbits, squirrels, etc. With all these advantages and the wide range of cost-effective options available to the modern grower, season extending is worth a good look. This section contains extenders for everyone, from large scale commercial operations to homescale growers. ROWCOVERS - Which One? Rowcovers can be divided into 2 categories: 1) heavier plastic covers, supported on frames or hoops to form a tunnel over the plants and 2) very light synthetic fabrics that "float" or rest directly on the crop. Plastic rowcovers are generally cheaper, but more labor-intensive because of the need for frames and the time for removal. Plastic rowcovers create higher daytime temperatures, which are desirable, for example, if you need to maximize soil warmth for early transplanting or to keep melons warm at the end of the season, etc. Floating rowcovers are more versatile in that they allow not only light and heat to penetrate but also some degree of water, sprays and air. Since there is no need to remove them during the season, they also tend to provide better protection against flying insects than plastic row covers. Many growers use rowcovers in combination with mulching film to achieve maximum soil warmth and weed control at the same time. See Weed Control section for mulching plastics. Hoop frames For inexpensive hoop frames, just bow pieces of 10 gauge wire (see wire hoops, next page) across the row, anchoring each end by burying it at least 1' in the ground. Some growers prefer frames of PVC pipe. FROST PROTECTION TIPS Spraying foliage with kelp extracts (see Liquid Fertilizer section) will increase the mineral content of the leaves, reducing the water in the cells, thus providing a few degrees of frost protection. To obtain full effect, spray plants weekly for a few weeks prior to the first expected frost. Another simple frost-protection technique is to turn sprinklers onto the frost-sensitive plants during the late hours of frosty nights. Leave the water on until after the sun has warmed the air above 32°F. The finer the sprinkler droplets, the better the effect; a fog is the best. Sprinklers should be on as soon as the temperature drops below 33°F. See our temperature monitors in Monitoring Tools. POLYCARBONATE GLAZING The best coldframes and greenhouses are glazed with ribbed, double-insulated, polycarbonate. This high-tech plastic (also used for airplane windshields and football helmets) is able to withstand extreme temperatures and high impacts. Double-wall polycarbonate also has 40% more insulation value than single pane glass, with nearly equal translucence. The ribbing scatters light evenly, eliminating hot spots and promoting straight, uniform growth. GREENHOUSE PLASTICS The plastics we sell for greenhouses should not be confused with construction grade plastic which yellows quickly and deteriorates within a few months. Prolong your plastic's lifespan by installing it without any direct contact with PVC pipe which chemically reacts to the poly and weakens it. Also, plastic deteriorates rapidly when exposed to extremely high temperatures inside your greenhouse. Always vent at the ceiling, at both ends to avoid the solar cooker effect. Back to Reference Library Index
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