Growing Vegetables Year-Round Fall and Winter Vegetable Production Four Keys To Success
Growing Vegetables Year-Round Nathan Johanning Extension Educator, Local Food Systems and Small Farms University of Illinois Extension Franklin/Jackson/Perry/Randolph /Williamson Unit
The Four Keys to Success Use of cold tolerant crops Timely plantings Use of multiple harvest crops Protection of the crop
How can plants freeze and survive? Repeated freezing and thawing of most plant cells disrupts them because of the repeated formation of sharp ice crystals. During the coolest weeks of the winter, leaf water content decreases in cold tolerant plants while soluble sugars increase substantially. Resulting in increased freezing tolerance.
Understanding heat and light Heat-comes from solar radiation and from the earth s ambient temperature. Plants need combinations of both to grow and produce. Trap and store the heat
How are conditions different? Summer: Excess of light and heat Management is geared to keeping plants cool and not exceeding critical temperatures Fall/Winter: Light and heat are limited must be captured and used efficiently. Maintaining a growing environment (heat and light) is goal
Angle of the sun s rays The more angled the roof-the more light you will intercept. The apparent path of the Sun across the sky. Note how much higher the Sun is in the sky in mid-summer! Credit: Stern (2001) NASA
Light Management Day length at 41 Latitude late December is about 9 hrs. Day length at same latitude in late June is about 16 hours. Question: Does this mean there is one-half the light in Dec versus June?
Light Management Answer: No In addition to decreasing day length in winter/fall, light intensity is drastically decreasing as well. Need to consider the Daily Light Integral (DLI)
Daily Light Integral (DLI) Measured in moles per square meter per day Example: DLI can range from 2.5 to 50 moles per day-a factor of 20! (Bierbaum, 2004) A cloudy day in December might experience 5% of the light that a sunny day in June might have. Plant growth needs to take place earlier in the season!
DLI continued When DLI drops below 10 for the day plant growth slows considerably (December/January) Remember, greenhouse plastic can reduce the light as well as will row covers. (from Bierbaum et.al 2004)
Temperature Management Average Daily Temperature-ADT For cool season crops, the temperature at which there is little or no growth is 32 to 35 F An example: If the range of base temperature to optimal temperature is 25 degrees for each 5 degrees increase in ADT the plants will grow about 20%
Temperature Management Soil temperature will be influenced by: Amount of sunlight Amount of soil moisture Air temperature So-soil temperature is a good indicator of overall energy (temperature) in the structure.
If the soil is dry, it is likely to be as cold as the temperature just above the soil. Dry soil is less dense. But if the soil is moist, the water will freeze when the temperature falls to about 32 F. As water freezes some heat is released, sufficient heat to keep the temperature from falling below 32 F as long as there is still some water transforming to ice. It is not uncommon to have the soil temperature fall rapidly to 32 F and then hold at 32 F for two or more days (nights) of air temperatures below 20 F.
High Tunnels High Tunnels are a great tool extend the season Unheated greenhouse structure Captures sunlight to produce heat During the middle of a sunny day you can easily get temperatures from 20 to more than 40 degrees warmer than outside!
St. Charles Research Center, Univ. of Illinois
Structure effect on thermal performance Layer(s) of poly..1 or 2? Insulated perimeter Insulated end walls Rule of thumb: 1 layer poly=1 growing zone
Structure effect on thermal performance Add foam board insulation material from the soil surface down to a 12-18 inch depth around the perimeter of a greenhouse or high tunnel. This can save significant heat and keep the soil along the walls 10-20 F warmer.
Structure effect on thermal performance Insulated endwall reduces heat loss.
Row Covers Provide up to 8 degrees of frost protection Must be managed daily Use 0.5 oz weight row cover and double if needed
Keep soil exposed Do not use mulch Do not use plastic Sometimes we do use black plastic when starting crops early in the spring but in order to be beneficial in warming the soil it MUST be tightly covering the soil. No air gap between plastic and soil! Air is an insulator and will slow the warming of soil You want the soil surface exposed to sunlight during the day to absorb heat!
Managing Row Covers The igloo effect Open covers on sunny days in the morning Cover crops at the end of the day before temps fall again Very cold conditions.maybe two layers of covers??
Other issues-early on in season Downy mildew -from condensation dripping on leaves. Solution: Use resistant varieties Aphids-rogue the plant or spot treat
What to Plant? Cold tolerant crops Late fall, winter, or overwintered crops? Balance hardiness and marketability Mostly extending the harvest season http://www.isws.illinois.edu/atmos/statecli/frost/frost.htm
What to Plant? Greens lettuces, spinach, asian greens, arugula, kale, chard, mache Roots carrots, beets, turnips, parsnips, radishes Alliums leeks, green onions Use seed catalogs to determine best varieties http://www.johnnyseeds.com/
25 F Cabbage, broccoli, cauliflower, napa cabbage, endive, mizuna, green onions, bok choy 22 F - Arugula, tat soi 20 F - Beets, celeriac, mustard greens, Italian parsley, radishes, turnips 15 F - Russian kale, some lettuces, cilantro 10 F - Chard, carrots, collards, daikon, rutabaga, leeks, large-leaf spinach 0 F - Chives, mache, parsnips, salsify, some spinach, Jerusalem artichoke What to Plant?
What to Plant? Varietal Selections for Winter Harvest Broccoli - Diplomat, Expo, Emerald Crown Cabbage - Savoy, January King, Blues Chard - Bright Lights, Rainbow green is hardier Kale Red Russian Pak Choy - Prize Choy, Joi Choi Pak Choy, Mizuna - Ruby Streaks Endive Perfect, President Green Onions Evergreen Winter Hardy White, White Lisbon Spinach - Space, Regiment, Covair, Tyee, Olympia, Bloomsdale Savoy Lettuces - Lollo Divino, Red Sald Bowl, Winter Wonderland, Revolution, Rouge d Hiver Carrots - Danvers, Oxheart, Napoli Beets - Red Ace, Albina, Verduna, Lutz Winterkeeper Leeks - Alaska, Durabel, American Flag, Bulgarian Giant, Laura, Tadorna
What to Plant Experiment! Refer to the Midwest Vegetable Production Guide for basic planting information. Do your own research Try other varieties (clearly marked) Use outdoor cemetery patch for varietal selection Find niches within the winter produce niche
When to Plant? Succession plantings beginning in late summer Plant enough volume to carry through slow regrowth Mid November to early February growth is very slow Expect # of days to harvest to increase (14-28 day margin) Determine when you want to harvest a crop and count backwards
When to Plant? Average Frost Free Period in IL, April 15 October 15 (varies by location) Plants can be sown outdoors and transplanted into hoops Weeks before 1 st frost to plant some crops: 12-14 weeks broccoli, cabbage, cauliflower, leeks 10 weeks - beets, daikon, lettuce, turnips, rutabaga 8 weeks - winter radish, fall spinach 7 weeks - kale 5 weeks - spring spinach
Planting Considerations Balance space, crop size, and disease management Plant rows more densely than outside production Raised beds can warm soil more quickly Plant seeds deeper than in spring (soil is warm, prevents drying) Begin with good tilth, avoid compaction Direct seeded crops may be more cold tolerant than transplants
Winter = low water requirements, crop grows slowly and HT is humid Drip tape is useful Water during middle of the day when a mild(er) night is forecast to reduce crop freeze Ventilate when possible Winter Watering
Winter Harvest Cut and come again crops Midday harvest on sunny days (4hrs) Cut above growing point every 15-35 days Do not remove more than 40% of leaf area at one time Use harvest to thin direct seeded rows Plan ahead for frozen ground
Recordkeeping Winter production is more expensive Harvests are smaller Keep all records (including labor time) and charge accordingly Not just about more $, also retaining satisfied customer base into next year!
Summary Remember: Use of cold tolerant crops Timely plantings Use of multiple harvest crops Protection of the crop
Questions?? Thank You! Nathan Johanning Extension Educator, Local Food Systems and Small Farms University of Illinois Extension Murphysboro, IL 62966 njohann@illinois.edu (618)687-1727