Fall Vegetable Production ©Pam Dawling 2016

Twin Oaks Community, Virginia Author of Sustainable Market Farming

Published by New Society Publishers

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What’s in This Presentation

A. Suitable crops for harvesting or planting in fall:

o Warm weather crops for fall harvest

o Cool weather spring/fall crops

o Cold-hardy crops to plant in fall and harvest in winter

o Overwinter crops for early spring harvest

o Winter hoophouse crops

B. Meeting the challenges of each season

C. Lots of Resources

D. My contact information

Extend the season without overextending yourself!

• Find the balance point at which the time, money and energy you put in are still definitely worthwhile. 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.

• An extension of two or three weeks takes only a little extra vigilance and a modest investment in rowcover .

• It’s much easier to get extra fall harvests for a month or two from mature plants you already have, than it is to get harvests a week earlier in the spring.

• 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.

• The pace is naturally slower - it’s not a second hectic summer: few weeds germinate and established crops need less attention.

Tired but unbroken. Credit Bridget Aleshire

Suitable crops for harvesting or planting in fall

Warm weather crops for fall harvest: • green beans, edamame

• cucumbers

• zucchini, summer squash

• cantaloupes (muskmelons)

• sweet corn

• tomatoes Green beans. Credit Kathryn Simmons

Formula to determine last safe planting date 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

Succession Crop Scheduling

• A way of planning sowing dates for even, continuous supplies of popular summer crops, such as beans, squash, cucumbers, sweet corn; year round lettuce and winter hoophouse greens.

• As well as planning your last sowings, you can plan a succession of sowings all summer.

Photo Credit: Kathryn Simmons.

For all the details, see my slideshow Succession Planting for Continuous

Harvests on SlideShare.net

Suitable crops for planting and harvesting in fall

Cool weather spring/fall crops: • beets, carrots, • chard, spinach, • lettuce, salad mix, • Asian greens, cauliflower, • turnips, rutabagas, • cabbage, broccoli, • kale, collards, kohlrabi, • radishes (large and small) • scallions Spinach and peas. Credit Kathryn Simmons

Cool weather fall crops With fall crops, even a difference of 2 days in sowing dates can make a difference of 2-3 weeks in harvest date, because plants grow slower as days get shorter and cooler. The “Days to maturity” listed in catalogs is usually for spring conditions. Plants may mature faster in warm fall soils or slower once the weather cools.

Danvers 126 carrots. Credit Kathryn Simmons

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. Or mid-August for early November.

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)

Tatsoi. Credit Wren Vile

Carrots • 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 flame the beds the day before the carrots are due to emerge (using “indicator beets”, which emerge the day before the carrots).

• We hoe between the rows as soon as we can see to do so.

• We weed and thin to 1” once the carrots are 1” tall. We use flags to mark our progress.

• Once the carrots are salad size, we weed again and thin to 3”

Photo credit Southern Exposure Seed Exchange

Scheduling fall carrots • 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.

• In November we harvest all of the carrots and store in perforated plastic bags in the walk-in cooler.

Danvers Half-long carrots. Credit Southern Exposure Seed Exchange

Beets

• Beets prefer soil temperatures of 50°F–85°F (10°C–29°C)

• Only 3.5 days to emerge at 86°F (30°C), but 14.6 days at 50°F (10°C).

• If you can maintain a soil temperature below 86°F in late summer, you only have to do it for a few days. Look for a forecast cooler spell or generous rainfall.

• Hand-sowing pre-sprouted seed is an option if the season is relentlessly hot.

• Sow 1/2″-1″ deep, tamp the soil, and keep the surface damp with daily watering until they emerge.

• If you want to flame-weed, use radishes as an indicator – they germinate 1-2 days faster than beets.

Crosby Egyptian Beet. Credit Southern Exposure Seed Exchange

Scheduling fall beets • For fall fresh eating and winter storage crops, we

sow beets on 8/1 or so, dry or soaked for 1-2 hours in a little water. (Don’t soak too long, or in a lot of water – beet seeds are easy to drown.)

• We usually sow pre-soaked by hand. Sometimes dry with the EarthWay chard plate 2 passes.

• We have 8/20 down as the last date - I think we have done them later.

• Harvested 9/20- 11/15 and stored in the walk-in cooler in perforated plastic bags, for winter.

Photo Detroit Dark Red Beet. Credit Southern Exposure Seed Exchange

Spinach and chard • Spinach is a challenging crop to start 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.

• Swiss chard germinates best at 85°F (29°C), so consider that as a substitute for a first sowing if the fall is impossibly hot.

Tyee spinach. Credit Kathryn Simmons

Scheduling fall spinach

• Fall sowing dates are quite exacting: Sept 20 is the latest we can sow spinach for harvesting October–early April, and Sept 20–30 sowings will not get big enough to harvest until late February.

• Winter Bloomsdale spinach. Credit Southern Exposure Seed Exchange

Lettuce

Heat-tolerant varieties also tolerate cold.

There are also specialized cold-hardy varieties that do not tolerate heat (because they have a relatively low water content). Sow these in fall and winter only.

Rowcover will provide a temperature gain of 4–6 F degrees (2.2–3.3 C degrees), depending on the thickness.

Lettuce may survive an occasional dip to 10°F (–12°C) with good rowcover — but not 8°F (–13°C), I can tell you!

Adolescent lettuce are more cold-hardy than full-sized plants.

Scheduling lettuce in summer & fall

The short version: sow heat-resistant varieties (which are also cold-resistant)

• every 6-7 days in June and July,

• every 5 days in early August;

• switch to cold-hardy varieties, sow 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. Kathryn Simmons

Cherokee Lettuce

Credit Johnnys Seeds

Lettuce varieties for fall and winter Particularly cold-hardy for outdoors: Brune d’Hiver Cocarde Esmeralda Galactic Green Forest Hyper Red Wave Kalura Lollo Rossa North Pole Outredgeous Rossimo Rouge d’Hiver Sunfire Tango Vulcan Winter Marvel

Rouge d’Hiver Lettuce

Credit Southern Exposure Seed Exchange

The Salad Bowls are not so good outdoors in cold weather but do well under cover. Icebergs do not survive frost.

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 (30°C).

Rutabagas and Turnips

Rutabagas can be stored in the ground (unlike turnips, except in warm climates). Mulch over them with loose straw once the temperatures descend near 20°F (–7°C).

Turnips do very well in the winter hoophouse. We also grow Purple Top White Globe outdoors in spring and fall. White Egg turnip.

Credit Southern Exposure Seed Exchange

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

Scheduling fall outdoor brassicas

We start sowing our fall brassicas for outdoor planting around June 26 and repeat a week later for insurance (July 3).

Last date for sowing these crops is about 3 months before the first fall frost date. In our case that means July 14–20.

Senposai. Credit Kathryn Simmons

Brassica transplanting We aim to transplant leafy

brassicas at four true leaves (3-4 weeks after sowing).

In hot weather transplant crops at a younger age than you would in spring - 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.

Vates kale. Credit Kathryn Simmons

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.

Asian Greens • A quick way to fill out your

market booth or CSA bags • A catch crop for spaces where

other crops have failed or otherwise finished early.

• Easier to germinate in hot weather than lettuce.

• Faster growing than lettuce • Some of the faster-growing

types are ready for transplanting 2 weeks after sowing (or you can direct sow them)

• Keep a flat of seedlings ready, pop plugs into empty spaces as they occur.

Ruby Streaks and mizuna. Credit Ethan Hirsh

For more details, see my slidehow Producing Asian Greens on SlideShare.net

Cold-hardy Asian Greens Tatsoi/tah tsoi • small, flat rosette of shiny, dark

green spoon-shaped leaves and white stems.

• Mild flavor, attractive appearance, easy to grow.

• extremely cold tolerant, hardy to 22°F (–6°C) or colder.

• Can direct sow and thin into salad mixes, leaving some to mature at 10" (25 cm) across for cooking greens.

• Can transplant at 6" (15 cm). • Kitazawa Seeds have a Red Violet

tatsoi, with an upright habit. • Takes 21 days to become baby

salads; • 45 days to reach cooking size;

Yukina Savoy • like a bigger tatsoi, with blistered

dark green leaves, greener stems and delicious flavor,

• about 12“ (30 cm) tall. • Both heat and cold tolerant. • Can transplant at 12" (30 cm). • Needs 21 days to reach baby size, 45

days to full size; Tatsoi, Yukina Savoy, Credit Ethan Hirsh

Yukina Savoy Outdoors in December After several nights at 16-17°F (-8 to -9°C)

More Cold-hardy Asian Greens Komatsuna - also known as mustard spinach and Summer Fest. Green or red, a large cold-tolerant plant 18" (45 cm) tall. Individual leaves can be picked and bunched, or the whole plant can be harvested. The flavor is much milder than the English name suggests. Baby salad size in 21 days, full size in 35 days; Senposai is quite heat and cold tolerant, a big plant with large, round, mid-green leaves. Usually harvested leaf-by-leaf. It can be very productive. Transplant it at 12"–18" (30–45 cm) spacing. Cooks quickly (much quicker than collards), and has a delicious sweet cabbagey flavor and tender texture. It is a cross between komatsuna and regular cabbage. It takes only 40 days to mature. Senposai. Photo Ethan Hirsh

Senposai in November – the young hoophouse crop is almost ready to take over from the well-used outdoor crop.

Suitable crops for planting in fall

Cold-hardy crops to plant in fall and harvest in winter: • spinach • kale • collards • cabbage • lettuce • carrots We grow our winter-harvest crops in our raised bed area, which is more accessible in winter and more suited to small quantities.

Deadon cabbage. Credit Johnny’s Seeds

Choosing cold-hardy crops Use the Winter-kill temperature chart of winter-hardy vegetables for crops that will survive your lowest temperatures, taking any crop protection into account.

Add some wind protection, if you can.

Look for the hardiest varieties. At our Zone 7 farm, we overwinter Vates kale without rowcover, but not Winterbor or Russian kales.

For details, see my slide show Cold-Hardy Winter Vegetables on SlideShare.net

Favorite hardy winter-harvest crops – kale and spinach

We grow about 2800 row feet of overwinter Vates kale for 100 people and plant another 1000 feet in spring. We grow similar amounts of Tyee spinach. We use double hoops and rowcovers and pick spinach throughout the winter, whenever leaves are big enough. We pick one bed each day in October, November, February and March, when the weather is not too awful. Spinach makes some growth whenever the temperature is above about 40°F (5°C), so we can also make occasional harvests in December and January.

Vates kale Credit Kathryn Simmons

More winter-harvest crops As well as kale and spinach, collards, leeks and parsnips also survive outdoors without rowcover at our farm (Zone 7). We grow only a few hundred feet of collards. Leeks and parsnips are slow growing, start them in spring. Lettuce can be grown outdoors with thick rowcover on hoops. We have also sometimes overwintered Danvers carrots and Deadon cabbage. Overwintered Vates kale

Winter-harvest leeks Unlike onions, leeks grow independently of day length and will stand in the field at temperatures below what many other vegetables can handle, increasing in size until you harvest them. Overwintered leeks.

Leek varieties - two main types:

• the less hardy, faster-growing varieties, often with lighter green leaves, which are not winter-hardy north of Zone 8,

• the blue-green hardier winter leeks. We like Tadorna (100 days), Jaune du Poiteau, King Sieg (84 days, a cross between King Richard and the winter-hardy Siegfried, from Fedco) and Bleu de Solaize (105 days, very hardy).

• Giant Musselburgh (105 days) is bolt-resistant, for overwintering in milder climates.

Other hardy winter-harvest crops • Small greens such as arugula, parsley, Belle Isle upland cress, winter

purslane, salad burnet and mache (corn salad) are very winter-hardy.

• Some Asian greens are hardy - Green in Snow mustard (Shi-Li-Hon) is the hardiest Asian green.

• Some unusual crops like horseradish, Jerusalem artichokes, salsify, and some endive are hardy.

• Walla Walla bulb onions and Evergreen Winter Hardy White or White Lisbon scallions are surprisingly hardy.

• Swiss chard is hardy to 15°F (–10°C) without rowcover. To keep chard overwinter, either use hoops and rowcover (in mild areas, Zone 6 or warmer), or else cut off the leaves in early winter and mulch heavily right over the plants.

• Bright Lights chard. Credit Wren Vile

For details, see my slide show Cold-Hardy Winter Vegetables

on SlideShare.net

Suitable crops for planting in fall

Overwinter crops for spring harvest • spinach • kale, collards, cabbage • lettuce, chard • carrots • chicories such as radicchio and

Sugarloaf, • scallions, potato onions • garlic, garlic scallions. • In mild areas, peas can be fall sown

for a spring crop. Sow 1" (2.5 cm) apart to allow for extra losses.

Planting garlic. Credit Brittany Lewis

For details, see my Growing Great Garlic slideshow on SlideShare.net

Scheduling overwinter crops for spring harvest

We sow one or two beds of spinach from 9/20-9/30, overwinter them as adolescents and harvest in the spring. These plants bolt later than the ones we harvest leaves from all winter, and earlier than spring-sown beds, so we get a continuous supply.

With alliums, such as bulb onions, multiplier onions and garlic, the harvest dates are regulated by day length, so the harvest cannot be earlier, but the bulbs will be bigger if you can overwinter the small plants.

Garlic scallions are a great early spring crop – easy, flavorful, unusual.

Garlic Scallions Small whole garlic plants. An attractive early crop

• Save small cloves from planting your main crop

• Plant close together in furrows, dropping them almost end to end, as they fall. Close the furrow and mulch over the top with spoiled hay or straw

• Plant next to your main garlic patch, or in a part of the garden that's easily accessible in spring.

• We harvest garlic scallions from early March till May, at about 7-8" (18-20 cm) tall,

• Trim the roots, rinse, bundle, set in a small bucket with a little water, and you're done!

• Scallions can be sold in small bunches of 3-6.

• Some people cut the greens at 10" (25 cm) tall, and bunch them, allowing cuts to be made every 2-3 weeks. We prefer to simply pull the whole plant. The leaves keep in better condition if still attached to the clove. Photo Kathryn Simmons

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 (left), Kathryn Simmons (right)

Suitable crops for planting in fall

Hoophouse crops:

• Salad crops,

• cooking greens

• turnips,

• radishes

• scallions

• bare root transplants for setting outdoors in February and March

Michihili cabbage.

Credit Southern Exposure Seed Exchange

See my slideshow Hoophouse in

Fall and Winter on SlideShare.net

Hoophouses for winter crops • Rate of growth is much faster inside

• Crop quality, especially leafy greens, is superb.

• In the hoophouse, it can be 7F warmer than outside.

• Plants can tolerate temperatures 14 F degrees lower than they can outdoors; they recover in the pleasant daytime conditions.

• With thick rowcover (1.25oz) in the hoophouse, plants survive 21F colder than they can outside.

• Working in winter inside a hoophouse is much more pleasant than dealing with frozen rowcovers outdoors.

• Greenhouses & coldframes are useful, but get a hoophouse if you can.

At a hoophouse temperature of10.4°F without rowcover, -2.2°F with, survivors included Lettuce, Mizuna, Turnips, Russian kales, Senposai, Tyee spinach, Tatsoi, Yukina Savoy.

Fall Hoophouse Planting - September Early September : We sow

sprouted spinach seed, radishes, scallions, Bulls Blood beet greens and tatsoi.

Sept 15 and Sept 24: We make outdoor sowings of crops to later transplant into the hoophouse.

At the end of September we transplant Tokyo Bekana and Maruba Santoh at 2 weeks old, Chinese cabbage, pak choy and Yukina Savoy at 3 weeks.

Photo November hoophouse beds. Ethan Hirsh

Fall outdoor sowings to transplant inside

• Sept 15: ten varieties of hardy leaf lettuce and romaines, pak choy, Chinese cabbage, Yukina Savoy, Tokyo Bekana, Maruba Santoh, chard.

• Sept 24: Red and White Russian kales, another ten varieties of lettuce, Senposai, more Yukina Savoy, mizuna and arugula.

• We use hoops and ProtekNet, and water frequently.

Senposai. Credit Kathryn Simmons

Fall Hoophouse Planting - October Oct 15 we sow turnips. We like

Red Round, Hakurei and also Oasis and White Egg.

Our neighbor Gary Scott sows beet plugs in mid Oct, transplants them in the hoophouse and harvests from mid-March. Ace in 72 plug trays.

In Late October we sow more filler greens, baby lettuce mix, spinach, turnips, chard and radishes.

At the end of October, we transplant Senposai, mizuna, the 2nd lettuce, kale, arugula and Yukina Savoy at 4 weeks old.

Mizuna Photo credit Ethan Hirsh

Early October, we sow more radishes and some “filler” greens, (spinach, lettuce and Asian greens). By mid-October we transplant lettuce at 10" (25 cm) apart, and chard.

Hoophouse Planting – November and December

Nov 10-20 - more turnips, mizuna and arugula, filler lettuce and spinach, scallions, tatsoi, radishes and our first bulb onions for field transplanting as early as possible in the new year.

From mid-Nov we aim to keep a fully planted hoophouse, and as each crop is harvested, we immediately replace it with another.

During December we use the “Filler” greens plants to replace casualties and heads of Chinese cabbage, Pak choy, Yukina Savoy each day as soon as we’ve harvested them.

Pak Choy replacing Yukina Savoy here. Credit Ethan Hirsh

Persephone days and scheduling winter hoophouse crops

• When the daylight is shorter than 10 hours a day not much growth happens. It depends on your latitude.

• In Central Virginia, latitude 38° North, this lasts 2 months, from November 21 to January 21. Soil temperature also matters. December 15-February 15 is the slowest growing time for us.

• 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 succession crops in the hoophouse

To maintain continuous supplies of salad and cooking greens, as well as radishes and small turnips, we plan several winter successions of hoophouse crops.

Daily hoophouse tasks in winter • Two hours work each day in winter in our 96’ x 30’ tunnel.

• Keep the temperature in the 65°F–80°F (18°C–27°C) range during the day, opening the big high windows, and the doors as needed. If the sun is shining we usually open the windows around 9 am and close them around 2:30 pm (a few hours before dark) to store some of the warmth.

• Even in cold weather, plants need fresh air! High-density cropping can really use up the carbon dioxide in a closed hoophouse very quickly. When this happens, photosynthesis crashes and plant growth becomes limited. Soil high in organic matter contains high levels of organisms that produce carbon dioxide. Dense plant canopies can trap this near soil level, where it is most useful.

• Our main task each day is harvesting. In the winter of 2009–2010, we had frozen soil or snow on the ground outside for a month (very unusual for us). Despite this we were able to keep a hundred people in fresh salad and cooking greens (with turnips and scallions for variety) for the whole month.

• Aside from harvesting, jobs include planting new crops, clearing old ones, spreading compost, hoeing, hand weeding and supplying water as needed.

• We have drip irrigation. In the middle of winter, not much water is needed, and we try to only water when a relatively mild night is forecast.

Nitrate accumulation

• During periods of short daylight length, there is a health risk associated with nitrate accumulation in leafy greens. Nitrates are converted in the body into toxic nitrites, which reduce the blood’s capacity to carry oxygen. Also, nitrites can form carcinogenic nitrosamines.

• Plants make nitrates during the night, and convert them into leaf material during the day. It takes about six hours of sunlight to use up a night’s worth of nitrates. In winter, a small handful of leafy vegetables can exceed the acceptable daily intake level of nitrate for an adult, unless special efforts have been made to reduce the levels.

• Spinach, mustard greens and collards contain about twice as much as lettuce; radishes, kale and beets often have two and a half times as much. Turnip greens are especially high, at 3 times lettuce levels.

To keep nitrate levels as low as possible:

Grow varieties best suited for winter; Avoid animal-based fertilizers; use organic compost. Ensure soil has sufficient P, K, Mg and Mo Water enough but not excessively; Provide fresh air as soon as temperatures reach 68°F (20°C), so that

carbon dioxide levels are high enough; Harvest after at least four (preferably six) hours of bright sunlight in

winter; Avoid harvesting on very overcast days; Avoid over-mature crops and discard the outer leaves. Harvest

crops a little under-mature, rather than over-mature; Refrigerate immediately after harvest, store harvested greens at

temperatures close to freezing; Use crops soon after harvest; Mix your salads; don’t just eat spinach.

Scheduling for a continuous and timely supply:

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 A Seedling Schedule for our greenhouse

production of transplants. A Hoophouse Planting Schedule A pocket notebook

Field Planting Schedule Draw up your list of outdoor planting dates, along with varieties, row feet, spacing, notes and space to write down what you actually do.

Seedlings Schedule

• Pepper transplants. Photo Kathryn Simmons

Meeting seasonal challenges: Dealing with the challenges of hot weather

Choose appropriate crops and varieties. Read catalog descriptions carefully. Look for flavor, productivity, disease resistance and cold-hardiness. Swiss chard will germinate in warmer soils than spinach.

Consider direct-seeding crops rather than transplants. They can be more cold-tolerant, probably because there’s no damage to the taproot.

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.

Sowing when soils are hot

1. Consult 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.

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.

Protection from pests

For summer nursery 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 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

Dealing with the challenges of cold weather - Extending the survival of frost-tender crops beyond the

first fall frosts

The first 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. Avoid frost pockets.

Seaweed foliar sprays used a few days ahead of expected frosts will toughen up cell walls and reduce frost damage.

Some growers take down the stakes or cages of tall plants like tomatoes, lay the plants down on the ground and cover.

Prepare a Frost Alert Card.

Frost Alert Card

• 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).

• Harvest or cover lettuce, zucchini, summer squash, cucumbers, beans, Chinese cabbage, pak choy and celery that won’t be covered.

• 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

Rowcover Lightweight, easy to use, easy to store. 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. 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 6 F degrees (3.3 C degrees) of frost protection.

Thinner types are for protection from insects. We use Agribon 17 (or 19), spun-bonded polypropylene 0.55 oz/sq yd, transmits 85% of sunlight, and offers 4 F degrees(2.2 C degrees) of frost protection.

Thinner rowcover can be used doubled up in severely cold weather, if you don’t have enough thick rowcover.

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. Ventilate covered crops in mild

weather, so they don’t lose their cold tolerance.

Hoops keep rowcover from sticking to frozen leaves and reduce abrasion. In winter we use double wire hoops — the outer hoops trap the rowcover so it doesn’t blow away. 9- or 10-gauge wire. The microclimate under hooped rowcovers is very pleasant in chilly, windy weather.

There are also spring steel hoops, for setting by machine or by hand. o Easy to store - they return to a

relaxed bow shape when removed from the soil, don’t get tangled.

o 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.

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.

Resources - General ATTRA attra.ncat.org

Market Farming: A Start-up Guide,

Scheduling Vegetable Plantings for a Continuous Harvest

Season Extension Techniques for Market Farmers

Intercropping Principles and Production Practices

Plugs and Transplant Production for Organic Systems

SARE at 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.

extension.org/organic_production The organic agriculture community with eXtension. Publications, webinars, videos, trainings and support. An expanding, accessible source of reliable information.

Growing Small Farms: growingsmallfarms.ces.ncsu.edu/ Farmer Resources, Farm Planning and Recordkeeping to download Joel Gruver’s spreadsheets.

Purple Mountain Organics, Tacoma Park, MD. Tools and supplies (ProtekNet) http://www.purpletools.net/protek-net-insect-pest-netting/

Resources - Planning The Twin Oaks Harvest Calendar by Starting Date and by Crop are available as

pdfs on my website sustainablemarketfarming.com/2013/11/07/growing-for-market-articles-2/

AgSquared online planning software: agsquared.com

COG-Pro record-keeping software for Certified Organic Farms: cog-pro.com

Free open-source database crop planning software code.google.com/p/cropplanning.

Mother Earth News interactive Vegetable Garden Planner, free for 30 days: motherearthnews.com/garden-planner.

Target Harvest Date Calculator: (Excel spreadsheet) johnnyseeds.com/t-InteractiveTools.aspx

Tables of likely crop yields: johnnyseeds.com/assets/information/vegetablecharts.pdf.

Mark Cain www.drippingspringsgarden.com under the CSA tab, you can download their Harvest Schedule. Notebook-based system.

Clif Slade’s 43560 Project: VABF newsletter vabf.files.wordpress.com/2013/08/clif-slade-43560-demo-project.pdf.

Resources - slideshows Many of my presentations are available at www.Slideshare.net. Search for Pam Dawling.

Crop Rotations

Cold-hardy Winter Vegetables

Crop Planning for Sustainable Vegetable Production

Fall Vegetable Production

Feed the Soil

Growing Great Garlic

Intensive Vegetable Production on a Small Scale

Producing Asian Greens

Production of Late Fall, Winter and Early Spring Vegetable Crops

Succession Planting for Continuous Vegetable Harvests

Sustainable Farming Practices.

Mark Cain: Planning for Your CSA: www.Slideshare.net (search for Crop Planning)

Daniel Parson: Planning the Planting of Cover Crops and Cash Crops, www.Slideshare.net

Joel B Gruver: Cover Crop Innovation www.Slideshare.net

Tom Peterson: Farm Planning for a Full Market Season Appalachian Farmers Market Association and Appalachian Sustainable Development http://vabf.files.wordpress.com/2013/02/tom-peterson-farm-planning-for-a-full-market-season.pdf

Brad Burgefurd: Cultural Practices And Cultivar Selections for Commercial Vegetable Growers. www.slideshare.net/guest6e1a8d60/vegetable-cultural-practices-and-variety-selection

Resources - books The Complete Know and Grow Vegetables, J K A Bleasdale, P J Salter et al.

Knott’s Handbook for Vegetable Growers, Maynard and Hochmuth

The New Seed Starter’s Handbook, Nancy Bubel, Rodale Books

The Organic Farmer’s Business Handbook, Richard Wiswall, Chelsea Green

Sustainable Vegetable Production from Start-up to Market, Vern Grubinger,

The New Organic Grower, Eliot Coleman, Chelsea Green

Extending the Season: Six Strategies for Improving Cash Flow Year-Round on the Market Farm a free e-book for online subscribers to Growing for Market magazine

Sharing the Harvest, Elizabeth Henderson and Robyn Van En

Gardening When it Counts, Steve Solomon

Grow a Sustainable Diet: Planning and Growing to Feed Ourselves and the Earth, Cindy Conner, New Society Publishers, (worksheet based). DVD/CD set Develop a Sustainable Vegetable Garden Plan

Crop Planning for Organic Vegetable Growers, Daniel Brisebois and Frédéric Thériault (Canadian Organic Growers www.cog.ca) Includes Excel spreadsheets or pdfs which can be downloaded blank.

Fall Vegetable Production ©Pam Dawling 2016

Twin Oaks Community, Virginia Author of Sustainable Market Farming

Published by New Society Publishers

SustainableMarketFarming.com

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