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Fall vegetable production (60min) - Pam Dawling
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Fall vegetable production (60min) - Pam Dawling

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Planning for vegetable production, including warm weather (frost-tender) crops, cool weather spring and fall crops and cold-hardy over-winter crops. Dealing with the challenges of establishing plants ...

Planning for vegetable production, including warm weather (frost-tender) crops, cool weather spring and fall crops and cold-hardy over-winter crops. Dealing with the challenges of establishing plants in hot weather and maintaining them in cold weather. Includes hoophouse (high tunnel) crops for fall and winter. Scheduling and techniques. Created by a grower in central Virginia, growing on 3.5 acres. Season extension, frost prediction and strategies for avoiding damage to crops.

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  • Silver Queen.
  • You probably can’t read the whole thing, so here’s an enlarged example of one of the boxes at the left
  • Draw a smooth line.
  • Along the top bar are numbers of days before and after the average first frost. Crops are listed down the left side and the chart shows when you can plant and when you’ll be able to harvest.
  • Sow more lettuce when the previous sowing germinates.
  • The clove you plant has the food supply to get growth started. Planting is done at a quieter time of year. It’s nice to have one of next year’s crops planted already.
  • In colder areas the goal is to get roots before the big freeze-up arrives, but not to make top growth until after the worst of the weather.
  • The peppers protected by foliage above them will often come through undamaged. The frosted top leaves die off, so before the next frosty night, we harvest another layer of peppers. This method allows us to get the highest number of ripe peppers, and also spreads out the harvest in a way that is more manageable.
  • If you wake early and find plants with that dreadful dark green glassy look of frozen death, you may be able to save them by watering immediately, either with sprinklers, or with a hose spray if the area you need to save is small. Just keep watering until the sun is shining on the plants and all may be OK.

Fall vegetable production (60min) - Pam Dawling Fall vegetable production (60min) - Pam Dawling Presentation Transcript

  • Fall Vegetable Production ©Pam Dawling 2013, Twin Oaks Community, Virginia Author of Sustainable Market Farming Published by New Society Publishers SustainableMarketFarming.com facebook.com/SustainableMarketFarming
  • One of the most important farm implements is the brain! • Food production requires planning • Before planning starts, be clear about your farming goals • At Twin Oaks our goal is to provide – a diverse, year-round supply – of tasty, fresh, organic vegetables and small fruit – for our intentional community of 100, – and grow enough to process for out-of- season use. • The stages of planning are cyclical • Information from each stage suggests changes for other stages
  • Pondering season extension  Success with season extension means finding the balance point at which the time, money and energy you put in are still definitely worthwhile.  Usually an extension of two or three weeks takes only a little extra vigilance and a modest investment in rowcover or shadecloth.  It’s much easier to get extra harvests for a month or two from mature plants you already have, than it is to get harvests a week earlier in the spring.  The further you try to extend the season of a crop beyond what is normal for your climate, the more energy it takes and the less financially worthwhile it becomes.  Credit Kathryn Simmons
  • Extending the season without overextending yourself! • Carefully consider what you can do to extend the season without overworking yourself, your crew, or your soil. • A longer harvest season helps you retain and satisfy customers. • And can help provide year-round employment for your crew, which helps you retain skilled workers. • If you decide to provide produce during the winter, you’ll find that the pace is naturally slower: few weeds germinate and established crops need less attention. It’s not a second hectic summer. Tired but unbroken. Credit Bridget Aleshire
  • Plan the year month-by-month: At Twin Oaks, to keep us on track, we use A descriptive month-by-month Garden Calendar, on my blog www.sustainablemarketfarming.com at the beginning of each month since July 2012. Maps of the layout of the crops in the various gardens, A Field Planting Schedule (part is in the handout), A Seedling Schedule for our greenhouse production of transplants. A Hoophouse Planting Schedule A pocket notebook
  • So many possibilities! The twin challenges of fall outdoor crops are sowing in hot weather, followed by keeping the crop happy in cold weather. Warm weather crops: green beans, cucumbers, zucchini, summer squash, cantaloupe s (muskmelons), swe et corn, edamame Cool weather spring/fall crops: beets, carrots, char d, spinach, peas, let tuce, turnips, rutab agas, radishes, cabb age, broccoli, kale, cauliflower, kohlrab i, collards, Asian greens, potatoes, sc allions Cold-hardy crops to over-winter: spinach, kale, collar ds, lettuce, carrots, cabbage, potato onions, garlic
  • Warm-weather crops - Succession planting for continuous harvests  Many vegetable crops can be planted several times during the season, to provide a continuous supply. Don’t stop too soon!  Typically, plants mature faster in warmer weather.  So, to get harvests starting an equal number of days apart, shorten the interval between one sowing date and the next as the season progresses.  Keep records and use information from other growers in your area to fine-tune planting dates. CREDIT: Kathryn Simmons.
  • Rough plan: Every 2 weeks for beans and corn, Sow another planting of sweet corn when the previous one is 1”–2" tall Sow more beans when the young plants start to straighten up from their hooked stage Every 3 weeks for squash, cucumbers, eda mame Every 4 weeks for carrots 2 or 3 plantings of muskmelons (cantaloupes) at least a month apart.
  • Making a good-fit plan Collect three pieces of information for each sowing of each crop: • Sowing date • Date of first harvest • Date of last worthwhile harvest of that sowing
  • Veg Finder Example: Squash #3 WEST Plot J Plant 6/23 120’ Planted….. Harvesting….. Finished….. BEANS CUKES SQUASH CORN CARROTS EDAMAME #1 29W, 29E Plant 4/16 180' dbl Planted Harvesting Finished #1 BED 13W Plant 4/20 90' Planted Harvesting Finished #1 BED 23W Plant 4/20 90' Planted Harvesting Finished #1 EAST Plot G 4x265’ Plant 4/26+4/29 1060' Bod Planted Harvesting Finished #1 BED 9E Plant 2/14 Danvers Planted Harvesting Finished #1 BED 21W Plant 4/26 90’ Planted Harvesting Finished #2 EAST Plot G Plant 5/14 176’ dbl Planted Harvesting Finished #2 EAST Plot I Plant 5/24 180’ slice 90' + pickle 90' Planted Harvesting Finished #2 EAST Plot I Plant 5/24 88’ Planted Harvesting Finished #2 EAST Plot G 4x265' Plant 5/21 1060' Bod/KK/SQ Planted Harvesting Finished #2 BED 25E Plant 2/28 Danvers Planted Harvesting Finished #2 EAST Plot G No-soak Plant 5/18 88’ dbl Planted Harvesting Finished #3 WEST Plot J Plant 6/7 240’ dbl Planted Harvesting Finished #3 WEST Plot J Plant 6/23 120’ Planted Harvesting Finished #3 WEST Plot J Plant 6/23 120’ Planted Harvesting Finished #3 WEST Plot A north 4 x 180' 6/6 1080' Sug Pearl /KK/SQ Planted Harvesting Finished #3 BED 12W Plant 3/13 Danvers Planted Harvesting Finished #3 EAST Plot I Plant 6/7 60’ dbl Planted Harvesting Finished #4 EAST Plot K Plant 6/29 175' dbl (5x35’) Planted Harvesting Finished #4 CENT Plot D Plant 7/15 240' slice 120' +pickle 120' Planted Harvesting Finished #4 EAST Plot K Plant 7/15 105’ (3x35’) Planted Harvesting Finished #4 WEST Plot A 6 x 180' 6/19 1080' Bod/KK/SQ Planted Harvesting Finished #4 BED 12E Plant 3/27 Danvers Planted Harvesting Finished #4 CENTRAL Plot D Plant 6/26 60’ dbl Planted Harvesting Finished #5 25E 22W Plant 7/19 180’ dbl (2x90’) Planted Harvesting Finished #5 BED 15E Plant 8/5 90' slicers Planted Harvesting Finished #5 BED 13E Plant 8/5 90’ Planted Harvesting Finished #5 WEST Plot A 6 x 180' Plant 7/2 1080' Bod/KK/SQ Planted Harvesting Finished #5 BED 19W Plant 4/10 Danvers Planted Harvesting Finished #5 EAST Plot K Plant 7/14. 70’ (2x35’)dbl Planted Harvesting Finished #6 BEDS 9W, 9E Plant 8/3 180’ dbl Planted Harvesting Finished #6 CENTRAL Plot D 7 x 200' Plant 7/16 1400' Bod/KK/SQ Planted Harvesting Finished #6 BED 17W Plant 5/14 Danvers Planted Harvesting Finished #8 BED 1 CARROTS#8 BED 30W Only if needed Plant 7/8 Danvers Planted Harvesting Finished #7 Not this year, perhaps never again #7 BED 27E Only if needed Plant 6/11 Danvers Planted Harvesting Finished #8 BED CARROTS #9 Overwinter Raised Beds Plant 7/28 Danvers Planted Harvesting Finished
  • Gather sowing and harvest start dates and draw graphs  Using your data, plot a graph for each crop, with sowing date along the horizontal (x) axis and harvest start date along the vertical (y) axis.  Mark the first possible sowing date and find the harvest start date for that.  Decide the last worthwhile harvest start date, mark that.  Then divide the period into a whole number of segments, according to how often you want a new patch.
  • Last worthwhile planting date Figure out the last date for planting each crop that gives it a reasonable chance of success. Virginia Co-operative Extension Service Fall Planting Guide http://pubs.ext.vt.ed u/426/426-334/426- 334.html
  • Formula for frost-tender crops Count back from the expected first frost date, adding: • the number of days from seeding to harvest, • the average length of the harvest period, • 14 days to allow for the slowing rate of growth in the fall, and • 14 days to allow for an early frost (unless you have rowcover - there is often a spell of warmer weather after the first frosts, and you can effectively push back your first frost date.) Zephyr Summer Squash CREDIT: Kathryn Simmons.
  • Example: Yellow Squash • number of days from seeding to harvest 50 • average length of the harvest period 21 • 14 days to allow for the slowing rate of growth in the fall 14 • 14 days to allow for an early frost (but we have rowcover) 0 days before the first frost = total of these = 85 last date for sowing, with October 14 first frost date = July 21 But using rowcover to throw over the last planting during cold spells, the growing season is effectively 2 weeks longer, and we sow our last planting of squash on Aug 5. We sow our last sweet corn July16 (90 days before our average first frost) and we harvest from around Sept 22. We sow our last edamame July 14. We sow our last beans 8/3, cucumbers 8/5. Credit Brittany Lewis
  • Cool weather spring/fall crops Some crops grow in spring and again in the fall - beets, carrots, chard, spinach, peas, lettuce, turnips, rut abagas, radishes, cabbage, broccoli, kale, cauliflower, ko hlrabi, collards, Asian greens, potatoes, scallions.
  • Scheduling fall cool-weather crops A general approach is this one from The Heirloom Gardener by Jeffrey Goss: • 10 weeks before the average first frost date (Aug 1 for us): beets, cabbage (Brunswick and January King for January harvest), daikon, leeks, winter lettuce (Marvel of Four Seasons, Rouge d’Hiver, Winter Density), turnips, rutabagas, watercress • 8 weeks before frost (Aug 15): winter radish, fall spinach • 7 weeks before frost (Aug 22): kale • 5 weeks before frost (Sept 7): spring spinach • 3 weeks before frost (Sept 21): fall globe radishes
  • Example calculation: Early White Vienna Kohlrabi  58 days from sowing to harvest.  Kohlrabi is hardy to maybe 15°F (–9.4°C). When is the temperature likely to drop to 15°F (–9.4°C)? Not before the beginning of November here.  We could sow kohlrabi in early August and get a crop at the end of October.  Credit McCune Porter
  • Fast Fall Crops for when time is short Some cool-weather crops mature in 60 days or less. Mostly these are greens and fast-growing root vegetables. Useful in case of crop failure. Ready in 30–35 days: • kale, arugula, radishes (both the very fast small ones and the larger winter ones). • many Asian greens: Chinese Napa cabbage, Komatsuna, Maruba Santoh, mizuna, pak choy, Senposai, tatsoi, Tokyo Bekana and Yukina Savoy. • spinach, chard, salad greens (lettuce, endives, chicories) and winter purslane. Ready in 35–45 days: • corn salad, land cress, sorrel, parsley and chervil. Ready in 60 days: • beets, collards, kohlrabi, turnips and small fast cabbage (Farao or Early Jersey Wakefield)
  • Beets and carrots Beets • Beets prefer soil temperatures of 50°F–85°F (10°C–29°C) • They take only 3.5 days to emerge at 86°F (30°C), but 14.6 at 50°F (10°C). • If you can maintain a soil temperature below 86°F, you only have to do it for a few days. Look for a forecast cooler spell or generous rainfall. • We sow beets on 8/1, dry or soaked for 1-2 hours in a little water. • Sow them 1/2″-1″ deep, tamp the soil, and keep the surface damp with daily watering until they emerge. Carrots (photo credit Southern Exposure Seed Exchange) • Carrots prefer soil temperatures of 45°F–85°F (7°C–29°C), • They germinate in 6 days at 80°F (27°C), their optimum. • Keep the soil surface damp until they come through. • We sow a large planting of fall carrots very early in August, enough to store and feed us all winter. Danvers 126 is our standard.
  • Spinach and chard • Spinach is a challenging crop in hot weather! • Optimum germination temperature 70°F (21°C) Max 85°F (29°C). Wait for soil temperature to drop (dead nettle, chickweed, henbit germinating). • For earlier planting, pre-sprout seeds one week. We sow sprouted spinach 9/1 or so. • 9/20-9/30 sowings over-winter small and make harvests in early spring. It grows every time air temperature tops 39°F (4°C). • Swiss chard germinates best at 85°F (29°C), so consider that as a substitute if the fall is impossibly hot. Tyee spinach. Credit Kathryn Simmons
  • Peas • can make a good fall crop if started early enough to mature before frosts. • 85°F (29°C) is optimum • 95°F (35°C) maximum. • Peas are easy to pre- sprout. • Mature pea plants are more easily killed by frost than seedlings. Sugar Daddy Snap pea, credit Hildegard Ott
  • Sowing lettuce in summer and fall  Lettuce likes 40°F–80°F (4°C–27°C).  Optimum 75°F (24°C) (germinates in only 2 days).  Max germination temperature is 85°F (29°C).  Sow late afternoon or at nightfall - better emergence than morning sowings. The short version on when to sow: sow heat- resistant varieties (which are also cold-resistant) • every 6-7 days in June and July, • every 5 days in early August, • every 3 days in late August, • every other day until Sept 21. • every 3 days until the end of September (for harvests through the winter). Cold-hardy (not heat-tolerant) Tango lettuce. Credit Kathryn Simmons Cherokee Lettuce Credit Johnnys Seeds
  • Brassica Surprise! Scarlet Ohno Revival Turnip Credit Southern Exposure Seed Exchange Most brassicas will germinate faster at 86°F (30°C) than at 77°F (25°C), provided the soil is damp. Turnips can be up the next day, even at 95°F (35°C). Winter radishes and daikon have no trouble germinating at high temperatures. But don’t expect much from the cabbage, broccoli, collards or cauliflower above 86°F
  • Broccoli, cabbage, kale and collards in fall  Direct sowing, in drills or in “stations” (groups of several seeds sown at the final crop spacing), is possible, if you have good irrigation.  If you use flats, it can help to have them outside on benches, above the height of flea beetles.  We use an outdoor “nursery” seedbed and bare root transplants, because this suits us best. The nursery bed is near our daily work area, so we’ll pass by and water it. Having the seedlings directly in the soil “drought-proofs” them to some extent; they can form deep roots and don’t dry out so fast. Cabbage plant. Credit Kathryn Simmons
  • When and how much to sow  Our seedbeds have an 8-week program  Our average first frost is Oct 14–20, and we sow broccoli and cabbage June 21– 27. Week 1 of 8.  Each week after the first week, we weed the previously sown plants, and thin to 1” (2.5 cm) apart. We check the germination, record it and resow to make up the numbers.  Rough formula for transplanted fall brassicas: sow around a foot (30 cm) of seed row for every 12'–15' (3.6–4.6 m) of crop row, aiming for three seeds per inch (about 1 cm apart). Broccoli one week after transplanting. Credit Kathryn Simmons
  • Brassica transplanting  We aim to transplant leafy brassicas at four true leaves (three to four weeks after sowing).  In hot weather transplant crops at a younger age than you would in spring, because larger plants can wilt from high transpiration losses.  If we find ourselves transplanting older plants, we remove a couple of the older leaves to reduce these losses. Morris Heading Collards. Credit Kathryn Simmons
  • Kale: direct sown/transplanted mix Our mixed direct-sow/transplant method allows for patchy germination, and requires less watering than if direct sowing it all. Three times, (8/4, 8/10, 8/16), we sow two beds with rows 10" (25 cm) apart and then carefully thin them, leaving one plant every foot (30 cm) We use the carefully dug thinnings from those beds to fill gaps and to plant other beds, at the same plant spacing. Another reason we use this system is that we want a lot of kale, and there isn’t time to transplant it all.
  • Protection from pests We deal organically with flea beetles, harlequin bugs and sometimes cabbage worms. For the seedbeds we use rowcover or ProtekNet (from Purple Mountain Organics) on wire hoops. Overly thick rowcover or rowcover resting directly on the plants, can make the seedlings more likely to die of fungal diseases in hot weather — good airflow is vital. For the transplanted crops, an 84" (2.1 m) width rowcover or mesh can form a tunnel over two crop rows 34” apart, giving good airflow. Photo credit Dubois Engineering
  • Fall brassica harvests • Cabbage Sept 25 - late November. • Main broccoli harvest period is Sept 10 - Oct 15. Smaller amounts picked either side of those dates. • Cauliflower heads need to be harvested before they get frosted. We use gaudy plastic clothes pins (easy to find) to clip the leaves over a developing curd once frosts threaten. The leaves are frost-hardy. • Kale and collards are harvested (by snapping off the bigger leaves) all winter in small amounts, and then in larger amounts as spring warms up, until the end of May, when they bolt. • Kohlrabi from Oct 20 - Nov 15. It stores well in perforated plastic bags in a walk-in cooler. In a plentiful year we have eaten stored kohlrabi all winter into early spring.
  • Cold-hardy crops to over-winter Cabbage, carrots, collards, ga rlic, kale, leeks, lettuce, potat o onions, parsnips, spinach. Leeks and parsnips are slow growing and fall is too late to start. In mild winter areas, peas can be fall sown for a spring crop. Sow 1" (2.5 cm) apart to allow for extra losses. In spring, overwintered plants give harvests sooner. Overwintered Vates kale
  • When to plant garlic • Fall-planting is best. Garlic emerges quickly in the fall • 9 am soil temperature 50°F (10°C) at 4” (10 cm) deep. We plant in early November. If the fall is unusually warm, wait a week. • Roots grow whenever the ground is not frozen • Tops grow whenever the temperature is above 40°F (4.5°C).
  • Garlic in winter  If planted too late, there won’t be enough root growth before winter, and you’ll get a lower survival rate and smaller bulbs.  If planted too early, too much tender top growth happens before winter.  Get enough top growth in fall so garlic has a roaring start in the spring, but not so much that the leaves cannot endure the winter.  If garlic gets frozen back to the ground in the winter, it can re-grow, and be fine. If it dies back twice in the winter, the yield will be lower than it might have been if you had been luckier with the weather.  When properly planted, garlic can withstand winter lows of -30°F (-35°C).
  • Multiplier Onions • Multiplier Onions, such as Potato Onions, are similar in needs to Garlic. • Fall planting (Sept-Nov) produces the best yields • They can be planted in very early Spring, if needed Yellow Potato Onions, Credit Southern Exposure Seed Exchange
  • Dealing with the challenges of hot weather It’s important not to act as if it’s April!  Choose appropriate crops and varieties. Read catalog descriptions carefully. Look for flavor, productivity, disease resistance and cold- hardiness.  Consider direct-seeding crops rather than transplants. They can be more cold-tolerant, probably because there’s no damage to the taproot.  Good soil preparation is important. Avoid over-cultivating before planting, as this makes crusting more likely.  Water a day ahead of planting, to reduce the need to water copiously afterwards.  Plant seeds deeper than you would in spring, as the soil is already warm and you don’t want seeds to dry out.  In dry conditions sow in sunken furrows.  Avoid hard tamping or rolling after planting.
  • Water Getting enough water to the seed and maintaining that level can be tricky in hot weather • Pre-water furrows for large-seeded crops. • After sowing, watering should be shallow and frequent. • For close-planted small seeded crops, use overhead sprinklers. • Drip irrigation is a help for direct seeded crops, although it can be hard to get even watering all along the row unless the emitters are closely spaced. • Chilled water, night watering, and even ice on top of the rows can help reduce soil temperatures as well as supplying vital moisture.
  • Sowing when soils are hot 1. Consult the tables in Nancy Bubel’s New Seed Starter’s Handbook or Knott’s Vegetable Grower’s Handbook, on the germination requirements for your crop, and the expected time to emergence under your field conditions – and use a soil thermometer. 2. If soil temperatures are too high for good germination, cool a small part of the outdoors: – Shade from other plants, shadecloth, boards, burlap bags, – For crops you normally direct seed, consider cooling a small nursery bed for your seedlings and transplanting later. 3. If outdoors is impossible, start seeds indoors: – Put a plastic flat of lettuce in your refrigerator or a cool room. – Use plug flats or soil blocks rather than open flats, to reduce transplant shock.
  • Soaking seeds A help when temperatures are high and soils are dry. The length of time to soak a seed depends on its size: bigger seeds benefit from a longer soak. Soak large seeds like beans and peas overnight before planting. It helps them get all the water they need to absorb for the initial sprouting. After that the smaller amounts needed to emerge are more easily found. Don’t soak legumes so long that the seed coat splits, or they may get attacked by fungi. Smaller seeds may only need to soak for 1-2 hours. I suspect that when I’ve had failures with soaked beet seeds it is because I soaked them for too long and they suffocated from a shortage of oxygen. Small seeds that have been soaked tend to clump together, so after draining off as much water as possible, mix them with a dry material like uncooked corn grits, oatmeal or bran, or use coffee grounds or sand. To use soaked or sprouted seeds in a seeder, spread them out in a tray for a while to dry the surfaces. Experiment on a small scale ahead of a big planting, to make sure your seeder doesn’t just turn the seeds to mush, or snap off any little sprouts.
  • Pre-sprouting seeds  To pre-sprout seeds, first soak them.  Then drain off the remaining water and put the seeds in a cool place.  Rinse twice a day, draining off the water.  Sprout the seed just until you see it has germinated. For most crops 0.2" (5 mm) is enough. For lettuce half that length is good, and one day may be time enough. Seeds with long sprouts are hard to plant without snapping off the shoot.  If your pre-sprouting has got ahead of the weather or the soil conditions, slow down growth by putting the seed in the refrigerator. For fall-sown spinach we do the whole one week sprouting process in the fridge, and we don’t rinse them very often at all!
  • Dealing with the challenges of cold weather - Extending the survival of frost-tender crops beyond the first fall frosts  The first radiation frosts may be very slight, and will often be followed by a few more weeks of warm weather. So it can be worth protecting susceptible crops. (Unless you’ve reached the exhaustion point we call “Praying for a Killing Frost.”)  When planning late crops, look for nooks with a warmer microclimate, more protection from the prevailing winds, a slope to the south, or perhaps a barn wall to the north. Avoid frost pockets where cold air collects at the bottom of a slope  Seaweed foliar sprays used a few days ahead of expected frosts will toughen up cell walls and make frost damage less likely.  Tall plants like tomatoes are not easily covered by rowcover. Some growers take down the stakes or cages, lay the plants down on the ground and cover them.  Prepare a Frost Alert Card.
  • Frost Alert Card • Cover lettuce, zucchini, summer squash, cucumbers, beans, Chinese cabbage, pak choy, lettuce and celery. • Harvest crops listed above that can’t or won’t be covered. • Harvest all ripe tomatoes, eggplant, corn, limas, cowpeas, okra, melons. • Harvest peppers facing the open sky, regardless of color. (Often only the top of the plant will get damaged by frost). • Check winter squash and harvest any very exposed squash. • Set up sprinklers for the night, on tomatoes, peppers and a cluster of beds with high value crops.
  • Sprinkler irrigation kept these tomatoes alive! Overhead irrigation can protect crops from early frosts in fall (or late frosts in spring). Sprinklers turned on just before frost started kept these plants warm enough to survive– as long as new ice kept forming on the plants. Once the sun came up and temperature rose above 32 F again, the sprinklers were turned off, the plants thawed out and were still alive. This method works because water gives off heat to the plants as it freezes into ice, and the formation of an ice shell around the plant prevents the colder air reaching the plants. Credit Southern Exposure Seed Exchange
  • DIY weather-forecasting Learn your local weather patterns by keeping records and watching what happens. • Our mid-Atlantic climate is controlled by three weather systems, mainly by moisture from – the Gulf of Mexico, – the Bermuda High Pressure area in summer, – the recurrent waves of cold Canadian air in winter. • Rain (fairly evenly distributed throughout the year in our county) – has slight peaks in January, February and March – and again in early June and August. • Some parts of our area can experience long periods of drought. – September-November is the drier season but it’s also the hurricane season, so the net result is very variable. • We use Wunderground, but subtract 5F° from their forecast night lows for our nearest town, and mentally downgrade the chance of rain by 10%, as rain often passes us by as it scoots along the river valley north of us.
  • Predicting frost Frost is more likely at Twin Oaks if: • The date is after 10/14 or before 4/30. • The Wunderground forecast low for Louisa Northside is 37°F (3°C) or less. • The daytime high temperature was less than 70°F (21°C). • The temperature at sunset is less than 50°F (10°C). • The sky is clear. • The soil is dry and cool. • The moon is full or new. • There is little or no breeze, although if temperatures are falling fast, the wind is from NW and the sky is clear, then polar air may be moving in, and we'll get a hard freeze. • The dew point forecast is low, close to freezing. Frost is unlikely if the dew point is 43°F or more.
  • Advection frosts There are two kinds of frost, advection and radiation, and the methods to mitigate damage are different from one another. • Advection frosts result from strong winds bringing in colder air from somewhere else. The sky may be cloudy or clear. • To fight advection frosts, insulation such as rowcover is the main approach. Trap as much warm air as possible before the cold stuff arrives. • Moving tender plants into a greenhouse and perhaps adding a little frost-protecting heating there, might be worthwhile. • Close up hoophouses, coldframes and greenhouses early in the afternoon, and preserve warmer temperatures. • Once the cold front arrives, daytimes may be grey and chilly too, with little chance of rewarming. Double rowcovers can be better than one thick one, because of the trapped air. Spraying water over rowcovers can add more protection. • Overhead irrigation, wind machines and other active methods are not effective in advection frosts, and only make the crops colder, as the cold air keeps moving through.
  • Radiation frosts • Radiation frosts are localized, not part of a large weather system. • If the skies are clear, and winds calm, night temperatures can plummet. Because there are no clouds to act as blankets on the earth, no winds to mix up the warmer and colder layers of air, and not much moisture in the air to slow the temperature change. • Days may be warm and sunny, but the nights can cool rapidly. • Radiation frosts can be combatted with rowcovers or other physical protection, • and also by using water or forced airflow (wind machines). • Overhead sprinkler irrigation can help against radiation frosts when the temperatures are not lower than 25°F and the winds are light. Water releases heat as it freezes. But if the wind speed is above 10mph, the evaporative cooling will increase the damage rather than improve things. • Surface drip irrigation can also provide a little warmth (5-7F°), but is only helpful if the soil is not already saturated.
  • Rowcover • Rowcover is a wonderful invention: lightweight, easy to use, easy to store. The edges need to be held down by bags of rocks or sand, plastic jugs of water, or metal or wooden stakes lying along the edges. • To protect against frost, you need a heavyweight rowcover. Thinner types are for protection from insects. – Dupont Xavan 5131 (previously called Typar). 1.25 oz/sq yd) fabric, can last for more than six years. Spunbonded polypropylene with UV stabilizers, 75% light transmission, and provides about 6 degrees F (3.3 degrees C) of frost protection. – We also like Agribon 17 (or 19), spun-bonded polypropylene 0.55 oz/sq yd, transmits 85% of sunlight, and offers 4°F (2.2°C) of frost protection for winter use. – We think polypropylene rowcover lasts longer and is tougher than polyester (Reemay). • Thinner rowcover can be used doubled up in severely cold weather, if you don’t have enough thick rowcover available. Photo credit Kathryn Simmons
  • Avoiding pitfalls of rowcover • If you are growing on bare soil rather than plastic mulch, weeds will grow very well, secretly and out of sight. • Rowcover reduces light levels. • It is a good idea to ventilate covered crops in mild weather, so they don’t lose their cold tolerance. • Hoops can be used to keep rowcover from sticking to frozen leaves and to reduce abrasion. We make hoops by cutting and bending 9- or 10-gauge wire. In winter we use double wire hoops — the outer hoops trap the rowcover so that it doesn’t blow away. The microclimate under hooped rowcovers is very pleasant in chilly, windy weather. Some growers use fiberglass rods, or hoops made from scrap plastic piping. There are also spring steel hoops, for setting by machine or by hand. These are easy to store as they return to a relaxed bow shape when removed from the soil and don’t get tangled. Their disadvantage is that they seem to come in just one length, 64" (1.63 m), which is fine for a single row of plants, but less good for our 48" (1.2 m) beds with multiple rows.
  • Low tunnels, caterpillar tunnels There are two versions of low tunnels (not tall enough to walk under): • Quickhoops cover more than one bed, and can be covered with rowcover topped by greenhouse plastic for the winter. Photo credit Johnnys Seeds • Caterpillar hoops are similar (usually narrower), and have the plastic or rowcover held down by ropes. Photo Credit Growing for Market
  • The hoophouse in winter We are amazed at how incredibly productive hoophouses are. • Rate of growth of cold-weather crops is much faster inside • Crop quality, especially leafy greens, is superb. • Plants can tolerate lower temperatures than outdoors; they have the pleasant daytime conditions in which to recover. Salad greens in a hoophouse can survive nights with outdoor lows of 14°F (–10°C). • Working in winter inside a hoophouse is much more pleasant than dealing with frozen rowcovers and hoops outdoors. • Greenhouses and coldframes also offer opportunities for cold-weather cropping, but get a hoophouse if you can.
  • Persephone days • When the daylight is shorter than 10 hours a day not much growth happens. • In Central Virginia, latitude 38° North, this period lasts two months, from November 21 to January 21. It depends on your latitude. • Soil temperature also matters. December 15-February 15 is the slowest growing time for us. • Be aware of the increase in days to maturity in winter. • To harvest in the darkest days of winter you’ll need to plan a good supply of mature crops to take you through. What has already grown before this period will provide most of your harvests. • For most of the winter, our hoophouse plants are actively growing, not merely being stored for harvest (as happens in colder climate zones and outdoors), so we can continue sowing new hoophouse crops even in December.
  • Winter hoophouse crop overview • Salad crops, cooking greens and some turnips, radishes and scallions. • Bare root transplants for setting outdoors in February and March. • In our climate, we can grow spinach, kale, collards and leeks outside all winter, but the rate of growth doesn’t compare to what happens in the hoophouse! • We aim to harvest greens in the hoophouse after the outdoor crops slow down, and turnips after the stored outdoor fall turnips have all been eaten, or as an occasional delectable alternative.
  • Fall outdoor sowings to transplant inside Using an outdoor nursery bed gives us cooler conditions for better seed germination, and allows our summer hoophouse crops longer to finish up. • Sept 15: about ten varieties of hardy leaf lettuce, pak choy, Chinese cabbage, Yukina Savoy, Tokyo Bekana, Maruba Santoh and chard. • Sept 24: Red and White Russian kales, another ten varieties of lettuce, Senposai, more Yukina Savoy, mizuna and arugula, and resows. • We use hoops and rowcover or ProtekNet to keep bugs off, and water frequently. • By the end of September we clear summer crops from a hoophouse bed, add compost and work it in. We transplant the Tokyo Bekana and Maruba Santoh at just 2 weeks old, the Chinese cabbage, pak choy and Yukina Savoy at about 3 weeks. (Plants grow so fast in September!) • By mid-October we clear and prepare another bed and transplant 280 lettuce at 10" (25 cm) apart, and the chard. • At the end of October we transplant the second lettuce (300 plants), the kale, Senposai, mizuna, arugula and the second Yukina Savoy at about 4 weeks old. Senposai credit Kathryn Simmons
  • Direct sown hoophouse crops • Early September, we sprout some spinach seeds for a week in a jar in the fridge, • Mid-September we sow the one-week-old sprouted spinach seed, some radishes, scallions, Bulls Blood beet greens and tatsoi. • Oct 24 we sow our first baby lettuce mix, second spinach and chard. • At the end of October we sow some “filler” lettuce and Asian greens to transplant later to fill gaps. We try hard to keep all the space occupied, mostly using lettuce and spinach. • Nov 10 we sow our second turnips, mizuna and arugula, more filler lettuce and spinach, and also our first bulb onions for outdoor transplanting as early as possible in the new year — we aim for March 1. • From Nov 10 on, we have a fully planted hoophouse • As each crop harvest winds down, we immediately replace that crop with another. Photo November hoophouse beds. Credit Ethan Hirsh
  • Resources 1  ATTRA Market Farming: A Start-up Guide, https://attra.ncat.org/attra- pub/summaries/summary.php?pub=18  ATTRA Scheduling Vegetable Plantings for a Continuous Harvest, www.attra.ncat.org/attra- pub/summaries/summary.php?pub=20  ATTRA Intercropping Principles and Production Practices (mostly field crops, but the same principles apply to vegetable crops), www.attra.ncat.org/attra- pub/summaries/summary.php?pub=105  ATTRA Season Extension Techniques for Market Farmers, https://attra.ncat.org/attra-pub/viewhtml.php?id=366  SARE www.sare.org -A searchable database of research findings  SARE’s Season Extension Topic Room  SARE Crop Rotations on Organic Farms, A Planning Manual, Charles Mohler and Sue Ellen Johnson, editors.  http://www.extension.org/organic_production The organic agriculture
  • Resources 2  Virginia Co-operative Extension Service Fall Planting Guide http://pubs.ext.vt.edu/426/426-334/426-334.html  Growing Small Farms: http://growingsmallfarms.ces.ncsu.edu/ Debbie Roos keeps this site up to the minute. Click Farmer Resources,  Purple Mountain Organics, Tacoma Park, MD. Tools and supplies http://www.purpletools.net/protek-net-insect-pest-netting/  Brad Burgefurd, Cultural Practices And Cultivar Selections for Commercial Vegetable Growers. Slide show. Wide scope. www.slideshare.net/guest6e1a8d60/vegetable-cultural-practices-and- variety-selection  Crop Rotations slide show http://www.slideshare.net/SustainableMarketFarming/vabf-2013-crop- rotations-for-vegetables-and-cover-crops-pam-dawling?from_search=5  Succession Crops slide show http://www.slideshare.net/SustainableMarketFarming/hhf-2012- succession-planting-for-continuous-vegetable-harvests-pam- dawling?from_search=3
  • Resources 3 - books  The Complete Know and Grow Vegetables, J. K. A. Bleasdale, P. J. Salter et al.  Knott’s Handbook for Vegetable Growers, Donald N. Maynard and George J. Hochmuth  The New Seed Starter’s Handbook, Nancy Bubel, 1988, Rodale Books  The Organic Farmer’s Business Handbook, Richard Wiswall, 2009, Chelsea Green  Sustainable Vegetable Production from Start-up to Market, Vern Grubinger, 1999,  The New Organic Grower, Eliot Coleman, 1995, Chelsea Green  Extending the Season: Six Strategies for Improving Cash Flow Year- Round on the Market Farm, a free e-book download for online subscribers to Growing for Market magazine  The Heirloom Gardener, Jeffrey Goss
  • Fall Vegetable Production ©Pam Dawling 2013, Twin Oaks Community, Virginia Author of Sustainable Market Farming Published by New Society Publishers SustainableMarketFarming.com facebook.com/SustainableMarketFarming