Root Crops in December

Root Crops to Plant in Central Virginia in December

A stormy winter day, garlic, rowcovered spinach beds and our hoophouse.
Photo Wren Vile

Reread Root Crops in October for more ideas of things you might plant, if you are in a much warmer climate zone than us. We are in winter-hardiness subzone Zone 7a, with an average minimum temperature of 0° to 5° F (-18°C to -15°C). We’re not planting anything outdoors in central Virginia in December. But in the hoophouse, we are sowing a couple of things.

Eliot Coleman has given the name Persephone Days to those with less than 10 hours of daylight, when little plant growth happens. Here in central Virginia, the Persephone Days last from November 21 to January 21.  Further north, the period is longer, and it is necessary to grow more of what you want to eat in winter and keep it in a holding pattern to see you through to the other side of the Persephone Days. The holding pattern could be crops in storage, which I wrote about in Root Crops to Plant in Central Virginia in November. Or it could be crops in the ground in a hoophouse.

Temperature also contributes to rate of growth and this is where hoophouse crops score big! It can be a lot warmer during sunny days inside a hoophouse, and our double-plastic hoophouse keeps nighttime temperatures about 8F (4.5C) degrees warmer than outdoors, sometimes 10F (5.5C) degrees warmer. In addition, plants can tolerate lower temperatures inside a hoophouse. The soil stays warmer and the plants recover in the warmer daytime conditions (it seems to be the night+day average temperature that counts). We find, in practice, the period of slowest growth here is December 15 to February 15: still two months long, but lagging the shortest days by three weeks. It takes time for the soil to cool down in late fall and time for it to warm up in early spring.

Hoophouse radishes and Yukina Savoy in December.
Photo Wren Vile

In our double-layer hoophouse, plants without any inner rowcover can survive 14F (7.7C) degrees colder than they could survive outside; with thick rowcover (1.25oz Typar/Xavan) inner covers, at least 21F (11.6C) degrees colder than outside. For example, salad greens in our hoophouse can survive nights with outdoor lows of 14°F (-10°C). Turnips (and many cooking greens) survived a hoophouse temperature of 10.4°F (-12°C) without rowcover, -2.2°F (-19°C) with.

In early December, we sow turnips #3. We sow Hakurei, Early White Egg, Oasis, and Red Round. They will struggle a bit to grow, so they are only worth sowing if we thin them promptly and harvest them on the small size, as the plants will start bolting in early March. See Root Crops in October, for details of thinning and harvesting.

In late December, we sow hoophouse radishes #5, Easter Egg and White Icicle. Cherry Belle and Sparkler types grow too fibrous at this time of year. See Root Crops in September for more about our succession of hoophouse radish sowing dates. Unlike the late October sowing which lasts for 8 weeks, the November sowing will only be good for the (slow-growing) four weeks of February, and this late December one for four weeks from mid-February to mid-March. In this case, it is because the temperature in the hoophouse and the daylength will have increased by then and the radishes will grow fast and start bolting.

Young Red Round turnips in our hoophouse in late November.
Photo Pam Dawling

Root Crops to Harvest in Central Virginia in December

In central Virginia, there are normally no roots that we could be harvesting outdoors in December except parsnips. Jerusalem artichokes are hardy down to 0°F (-18°C), but we haven’t grown those in decades. Horseradish is similarly hardy, but not a mainstay of nutrition. The months with R in them are the horseradish harvest months. This is not woo-woo, it happens that September to April have R in them, and the summer months do not!

Horseradish regrowing up through the mulch in early spring.
Photo Kathryn Simmons

If temperatures have not yet dropped to 12°F/-11°C, we could dig Danvers carrots, Cylindra beets, and any rowcovered rutabagas (swedes). Albina Verduna, and Lutz Winterkeeper beets are hardy down to 15°F (-9.5°C), as are most kohlrabi and rowcovered turnips. But we don’t take that chance. We like to gather our root crops in and have them safely stored. We also like to put our feet up more in December!

Covered beets, covered winter radish are OK down to 10°F (-12°C).

In the hoophouse we can harvest radishes #2 until 12/25, #3 (sown October 30) from 12/15 to 2/1. We harvest our first turnips (sown around October 13) as thinnings from November 29 and by pulling out the biggest from December 5, until mid-February, by which time we can have made a start on the second sowing (October 25).

Turnips in our hoophouse in December.
Photo Wren Vile

See my list of Winter-Kill Temperatures of Cold-Hardy Winter Vegetables 2020 for a more complete picture of “Harvesting in Time”

Other Root Crop Tasks in Central Virginia in December

From storage we can eat (if we grew them!) beets, carrots, celeriac, kohlrabi, parsnips, potatoes, rutabagas, sweet potatoes, turnips. Stored crops need to be visited at least once a month and checked for decay.

In our winter squash cage we keep some pancake turners rejected by the kitchen crew. If a squash is having a meltdown, I slide it onto a tray or a bucket lid and throw it outside. The first time I did that this year, I made the mistake of sliding a second squash on top of the first on my bucket lid. The first one couldn’t support the weight of the second. Messy! Sliding them into a bucket would have been safer.

A fine winter squash medley (no, they’re not root crops!)
Photo Southern Exposure Seed Exchange

Special Root Crop Topic for December in Central Virginia

Crop Review and Planning Part One

This is a wider task, not restricted to root crops. In November we have a Crop Review, and then start to plan our crops for next year. We like to get our seed orders in early, to maximize our chances of getting the varieties and quantities we’d like. Some seeds might be in short supply this time, because of all the new gardeners and Covidsteaders that joined our ranks this year.

We consider how well our crops did in terms of plant vigor, disease-resistance, yield, quality, flavor and timing. Did they come in all at once? A benefit for storage crops or those you might sell wholesale. Not so great if you want an extended harvest period.

Planting dates, soil quality, sufficiency (or otherwise) of pest and weed control, plant protection from the elements are all factors that affect yield and crop quality. We can plan to make changes to those things next year. We can decide to plant a different amount, or spread out the planting dates. This can lead to a new calculation of how much seed to buy for the coming year.

By now the seed catalogs are starting to arrive and we can look at what varieties are on offer. Is there a faster-growing turnip? A different carrot we’d like to try? Something with more resistance to the disease we noticed this past year? Something more recommended for our climate or region? While you’re browsing, make a back-up plan if you can’t get your first choice, either from the same catalog, or another.

Hoophouse turnips and baby lettuce mix in December (note the low sun angles!)
Photo Wren Vile

Twin Oaks October Calendar (Slowing Down)

Morris Heading Collards – our favorite
Photo credit Kathryn Simmons

Here’s our list of tasks for October. If you garden in zone 6 or 7, your list might be similar. If you live in a very different climate zone, leave a comment about your list for October, and how many weeks different your area is from ours.

During the month

Weed and thin fall crops in raised beds, especially spinach and kale. Thin carrots to 3”, kale to 12”.

Lettuce Factory: Transplant sowing #37 to fill cold frames; #38, 39, 40, 41, 42 in Greenhouse beds (9″ spacing).

Frost Alert:

Watch the forecast and if frost is expected that night

When frost threatens, harvest all peppers exposed to the sky. Corona is one of our favorite orange peppers. Photo credit Kathryn Simmons

Harvest peppers facing the sky, tomatoes, cauliflowers, corn, cowpeas, limas, eggplant, melons, cukes, okra, winter squash, Blues cabbage (hardy to 25°F), if not already done.

Double hoop and cover: lettuce, celery (hardy to 16°F with row cover).

Spring hoop and cover: squash, cucumbers.

Cover celery to extend the harvest into mid-winter. We like Ventura.
Photo credit Kathryn Simmons

Rowcover (no hoops): beans, Chinese cabbage, pak choy, Tokyo bekana, seedlings for hoophouse, collards  (hardy to 10°F, but cover keeps quality).

Cold frames:  Row cover between 32-28°F.  Add lids between 28-15°F.  Add quilts below 15°F.

Foliar spray greens with seaweed a few days before frost, to toughen them up.

Use overhead irrigation on peppers & tomatoes at night and some raised beds with tender crops.

Early Oct: Finish sowing spinach, kale by 7th for overwintering (last chance).

Transplant lettuce #37 to fill cold frames; #38, 39 in Greenhouse (9″ spacing).

Roll up drip tape from winter squash and sweet potatoes.

It’s time to roll up the drip tape from the watermelon, winter squash and sweet potato patches, in preparation for disking and sowing winter cover crops.
Photo credit Kathryn Simmons

Move stored garlic from basement to fridge – store below 40°F or above 56°F, never 40-50°F.

Mid Oct: Till finished raised beds and sow wheat or rye before the end of the month.

Garlic Beds: Compost (5-6 tractor buckets), till and prepare beds.

Transplant lettuce #40, 41, 42, 43 in Greenhouse as needed, filling any gaps.

Get soil tests done, when soil is not too wet.

5th fall disking: By mid-month disk and sow cover crops where possible. Sow wheat or rye as covercrops – too late for oats or most clovers (Austrian Winter Peas Sept 15-Oct 24).  Could sow winter wheat mid-Sept to early Nov (good for small plots that are hard to reach with the tractor) and after sweet potatoes).

Harvest peanuts mid-late Oct after a light frost.  Wash, dry, cure 6 days in solar dryer facing east (don’t heat over 85°F), store.

A well-covered sweet potato patch.
Photo credit Kathryn Simmons

Harvest sweet potatoes before soil temps go much below 55°F, or night air goes below 50°F: on 3 mild days – generally in the week that first frost usually occurs (10/7-14). Even a few hours exposed to temps below 50°F will cause chilling injury. (Frost on the leaves does not of itself damage the roots). Clip vines, dig carefully, set tubers in plant-clusters to dry on the soil. Select seed tubers (med-size tubers from high-yielding plants).  Save 100 Georgia Jet, 100 Beauregard, 20 each White and Jubilee. Cure in boxes with wood spacers and cover with newspaper, in basement with furnace going full time, for 7-10 days (85-90°F, 80-90% humidity).  Use fans. Splash water on floor. Curing is complete when skin is undamaged after rubbing two together. Restack boxes in storage cage.

Harvest white potatoes before the first frost (average Oct 14) if possible. Cure in root cellar at 60-75°F for 2 weeks, with good ventilation, then cool the cellar to lower temperatures: 50°F by 10/31, then 40°F for the winter.

Late Oct: Transplant lettuce #44, 45, 46 as filler in Greenhouse. Double hoop and cover spinach.

Planning: List successes & failures from labels. Prepare Garden Planning Schedule, Crop Review Sheets. Clean labels after info is recorded. Pray for a killing frost. File crop record info. Audit labor budget and plan endgame. Plan main garden layout. Hold Crop Review meeting.

Clear winter squash, tomatoes and peppers in order to sow cover crops, by 10/24 if possible. Sow rye alone or with crimson clover or winter peas. Crimson clover by 10/14; AWP, wheat by 11/8

6th fall disking: After the killing frost, or end of Oct if no frost: pull up tomato stakes and roll up drip tape, disk nightshades, melons, winter squash, sweet potato and white potato patches.

Check through veg in storage, squash once a week, white potatoes two weeks after harvest.

Perennials:Last mowing of clover in grapes in early Oct, not too short, and not too late in the year. Weed & mulch strawberry beds, and remove extra runners. Renovate if not already done. Start weeding, fertilizing and mulching the blueberries, raspberries, rhubarb and grapes.

Time to say goodbye to the rhubarb until April.
Photo credit Kathryn Simmons

October Harvests: Asparagus beans, beans, beets and beet greens, broccoli, cabbage, cantaloupes, carrots, cauliflower, celeriac, celery, chard, Chinese cabbage, collards, corn, cow peas, cukes, edamame, eggplant, horseradish, hot peppers, kohlrabi, komatsuna, leeks, lettuce, limas, maruba santoh, okra, pak choy, peppers, radishes, Roma paste tomatoes, scallions, senposai, spinach, tatsoi, tokyo bekana, tomatoes, turnips and turnip greens, winter radishes, winter squash, yukina savoy, zucchini.  Could lightly harvest rhubarb before frost.

Twin Oaks September Garden Calendar

Welcome to Twin Oaks!
Photo by Bridget Aleshire

THE SECOND SPRING

Here’s our Garden Task List for September: 

During the month

Weed and thin carrots and brassicas (kale to 12”).

Lettuce Factory: Sow hardy lettuce every 2 days till 21st, (3 rows/planting) then every 3 days. Sow #34-46 this month. Transplant 120 every 3-5 days (1/3 bed) #27, 28, 29, 30, 31, 32, 33 for last outdoor planting (Dec harvest). Transplant  #34, 35, 36  9/24-9/30 for frames

Root cellar: air and cool to 60°F by mid-September

Collect seed from Roma tomatoes if necessary.

Screen compost and fill old greenhouse beds before October, for winter lettuce and spring seed compost.

Early Sept: Prepare and plant new strawberry beds if not done in late August, using rooted potted runners or plants carefully thinned from last year’s beds (see August for details).

Transplant collards and kale if necessary. Transplant lettuce #27, 28, 29, 30.

Retrieve spinach and onion seeds from the freezer. After acclimating spinach seeds, sprout 4oz/bed (1 cup/10,000 seeds) for spinach #1 in fridge for one week, then direct sow (if <68°F, and dead nettle has germinated). If still hot, sow (preferably pre-sprouted) spinach in Speedling flats in float tank. 9/20 is last sowing date for fall harvesting. [Could broadcast oats into spinach at planting time for weed control & cold weather protection.]

Sow if not done already: kale and collards by 9/15; turnips by 9/30; radishes, kohlrabi, daikon and other winter radish, miscellaneous fall greens, scallions.

Plant large potato onions this month or early in October, at 8” (wider if supply limited). Cover with ½-1” soil, mulch with hay.

2nd fall disking: Watermelon plot when 800 have been harvested. Roll up drip tape first, or move to new strawberries.

Mid Sept: 7-14 Sept is the best time to sow vetch & rye, 1:2, 2# of mix/1000 sq ft (75#/acre) on old spring broccoli patch; crimson clover and rye, 1:2, at 55#/acre.

Transplant lettuce #31, 32.

Sow 1st sowing of hoophouse seedlings (hoop and cover).

Bring 6 tractor buckets compost to hoophouse for fertilizing fall and winter crops.

Move stored onions from basement to fridge, after apples peak in mid-September, and space available.

3rd fall disking: corn #3, #4, #5. Part of corn #3 plot may be used for new strawberry beds.

Late Sept: Sow spinach #2 for spring harvesting (9/20-9/30), and 2nd sowing of hoophouse seedlings and cover.

Transplant kale for spring, filling gaps; lettuce #33, finishing up the last outdoor bed; [#34, 35 & 36 in cold frames?] Plant large potato onions (>2”) if not done earlier.

Move garlic from basement to fridge late September-late Oct as needed to make room for winter squash.

Weeding: this is a good catch up time on weeding in the raised beds.

4th fall disking and seeding: Sow cover crops wherever possible (in unused raised beds too). The last chance for oats is early Sept (9/15??). Can sow winter wheat (winter-killed in zone 4) or winter barley (dies in zone 6) if oat planting date missed. (Oats winter-kill in zone 8). Can sow hardy Austrian winter peas in late Sept at 8oz/100sq.ft. with rye. Can sow red clover this month.

Bush-hog late corn if undersown with oats and soy cover crop.

Perennials: New strawberry beds: Prepare and plant by mid-September if not done in late August. Weed strawberries. Could till up grass in grape alley & sow clover if not done in March. If clover sown earlier, let it seed.

Harvest and store winter squash: Acorn (pepo) types (stem still green, ground spot “earthy” or orange), store 1-4 months; Maximas: Cha Cha, Jarrahdale, Kabocha (stem 75% corky) store 3-5 months; Moschatas: Butternuts, Cheese (peanut colored skin, no mottling or streaks) store 4-8 months, or more. Leave on live vines as long as possible, avoiding frost on fruits. Cut leaving long stem using pruners; handle gently.

September Harvests: Asian melons, asparagus beans, beans, beets and beet greens, broccoli, cabbage, cantaloupes, carrots, cauliflower, celery, chard, Chinese cabbage, corn, cow peas, cukes, edamame, eggplant, horseradish,leeks, lettuce, limas, maruba santoh, okra, pak choy, peppers, hot peppers,radishes, Romas, scallions, senposai, summer squash, Tokyo bekana, tomatoes, turnips, watermelons, winter squash, yukina savoy, zucchini.  It is possible to lightly harvest rhubarb during September, if wanted.

 

Winter Hardiness

It can be hard to find out just how cold a temperature various vegetable plants can survive. Reading books written in different parts of the country can be confusing: “survives all winter” is one thing in the Pacific Northwest and another in Montana. So for some years I have been collecting data and exchanging information with my friend and neighbor Ken Bezilla at Southern Exposure Seed Exchange. Each winter I try to record what dies at what temperature. Below is my current list, which should be treated as a work in progress.

Your own experience with your soils, microclimates and rain levels may lead you to use different temperatures. If you have data from your garden, please leave a comment. Likewise if you have found particular varieties to be especially cold-tolerant, I’d love to learn more. Central Virginia isn’t the coldest spot in the US, but if I can grow something without rowcover, I’m happy to hear it!

Here’s our temperature list at which various crops die:

 35°F (2°C):  Basil.

32°F (0°C):  Bush beans, cauliflower curds, corn, cowpeas, cucumbers, eggplant, limas, melons, okra, some Pak Choy, peanuts, peppers, potato vines, squash vines, sweet potato vines, tomatoes.

27°F (-3°C): Most cabbage, Sugarloaf chicory (takes only light frosts), radicchio.

 25°F (-4°C): Broccoli heads, chervil, chicory roots for chicons, and hearts, probably Chinese Napa cabbage (Blues), dill, endive (hardier than lettuce, Escarole more frost-hardy than Frisée), annual fennel, large leaves of lettuce (protected hearts and small plants will survive even colder temperatures), some mustards and oriental greens (Maruba Santoh, mizuna, most pak choy, Tokyo Bekana), onion scallions, radicchio. Also white mustard cover crop.

22°F (-6°C): Arugula, Tatsoi. (both may survive colder than this.) Possibly Chinese Napa cabbage (Blues), Maruba Santoh, Mizuna, Pak Choy, Tokyo Bekana with rowcover.

20°F (-7°C): Some beets, cabbage heads (the insides may still be good even if the outer leaves are damaged), celeriac, celtuce (stem lettuce), some corn salad, perhaps fennel, some unprotected lettuce – some OK to 16°F (-16 °C), some mustards/oriental greens (Tendergreen, Tyfon Holland greens), radishes, turnips with mulch to protect them, (Noir d’Hiver is the most cold-tolerant variety).

17°F (-8°C): Barley (cover crop)

15°F (-9.5°C): Some beets (Albina Verduna, Lutz Winterkeeper), beet leaves, broccoli leaves, young cabbage, celery (Ventura) with rowcover (some inner leaves may survive at lower than this), cilantro, endive, fava beans (Aquadulce Claudia), garlic tops may be damaged but not killed, Russian kales, kohlrabi, perhaps Komatsuna, some covered lettuce, especially small and medium-sized plants (Marvel of  Four Seasons, Rouge d’Hiver, Winter Density), curly leaf parsley, flat leaf parsley, oriental winter radish with mulch for protection (including daikon), large leaves of broad leaf sorrel, turnip leaves, winter cress.

12°F (-11°C): Some cabbage (January King, Savoy types), carrots (Danvers, Oxheart), multi-colored chard, most collards, some fava beans (not the best flavored ones), garlic tops if fairly large, most fall or summer varieties of leeks (Lincoln, King Richard), most covered lettuce (Freckles, Hyper Red Rumpled Wave, Parris Island, Tango) , large tops of potato onions, Senposai, some turnips (Purple Top).

10°F (-12°C): Beets with rowcover, Purple Sprouting broccoli for spring harvest, Brussels sprouts, chard (green chard is hardier than multi-colored types), mature cabbage, some collards (Morris Heading), Belle Isle upland cress, some endive (Perfect, President), young stalks of Bronze fennel, perhaps Komatsuna, some  leeks (American Flag), Oriental winter radish, (including daikon), rutabagas, (if mulched), tops of shallots, large leaves of savoyed spinach (more hardy than flat leafed varieties), tatsoi, Yukina Savoy. Also oats cover crop.

5°F (-15°C): Garlic tops if still small, some kale (Winterbor, Westland Winter), some leeks (Bulgarian Giant, Laura, Tadorna), some bulb onions (Walla Walla), potato onions and other multiplier onions, smaller leaves of savoyed spinach and broad leaf sorrel.

0°F (-18°C): Chives, some collards (Blue Max, Winner), corn salad, garlic, horseradish, Jerusalem artichokes, Vates kale (although some leaves may be too damaged to use), Even’ Star Ice-Bred Smooth Leaf  kale, a few leeks (Alaska, Durabel); some onion scallions (Evergreen Winter Hardy White, White Lisbon), parsnips, salad burnet, salsify, some spinach (Bloomsdale Savoy, Olympia, Tyee). Also small-seeded cover crop fava beans.

Even Colder: Overwintering varieties of cauliflower are hardy down to -5°F (-19°C).

Many of the Even Star Ice Bred varieties are hardy down to -6°F (-20°C).

Walla Walla onions sown in late summer are hardy down to -10°F (-23°C).

Winter Field Peas and Crimson clover (used as cover crop) are hardy down to -10°F (-23°C).

Hairy vetch and white Dutch clover cover crops are hardy to -30°F (-34°C)

Sorrel and some cabbage (January King) are said to be hardy in zone 3, -30 to-40°F (-34 to -40°C)

Winter wheat and winter rye (cover crops) are hardy to -40°F (-40°C).