More About Winter Vegetable Storage

 

Bucket of freshly harvested Detroit Dark Red beets for storage.
Photo Pam Dawling

 See my previous posts

Here I will tell you more about storage of various crops.

  • Storing crops maximizes their season of availability
  • Many crops can be stored without electricity, perhaps in buildings that serve other uses at the height of the growing season.
  • The Washington State University Extension publication, Storing Vegetables and Fruits at Home, is a good introduction to alternatives to refrigerated storage, using pits, clamps and root cellars. Drawings below are from WSU Storing Vegetables and Fruits at Home
  • There is also good information in old versions of the USDA Agriculture Handbook 66.
  • Some vegetables need to cure before storage in different conditions from those needed for storage. Curing allows skins to harden and some of the starches to convert to sugars.
A storage cabbage, with curled-back leaf on the head, showing maturity.
Photo Bridget Aleshire

Four Sets of Vegetable Storage Conditions

See the chart in my book Sustainable Market Farming, for more details.

By providing storage spaces with just 4 types of conditions, at least 25 crops can be stored.

A= Cold and Moist: 32°F–40°F (0°C–5°C), 80%–95% humidity — refrigerator or winter root cellar conditions. Most roots, greens, leeks. Use ventilated crates, or perforated plastic bags (or mesh net bags for cabbages) indoors. If above 45°F (7°C), roots will start to sprout. Greens benefit from light. See more about root cellars below. Roots can be stored in clamps or pits outdoors – more on those options below.

B= Cool and Fairly Moist: 40°F–50°F (5°C–10°C), 85%–90% humidity — root cellar. Potatoes. Use ventilated crates. Keep in darkness to prevent greening. See the links to my potato storage info.

Trimming garlic stems prior to long-term storage.
Photo by Brittany Lewis

C= Cool and Dry: 32°F–50°F (0°C–10°C), 60%–70% humidity — cooler basements and barns. Garlic and onions. Use net bags or shallow racks. Avoid temperatures of 40°F-56°F (4°C-13°C), or they will sprout. Also avoid reversals of temperature (warm conditions after cold ones). Newer info says 32°F-40°F (0°C-4.5°C). is best for garlic.

Sweet potatoes stored in off-duty wood seed flats.
Credit Nina Gentle

D= Warm and Dry to Fairly Moist: 50°F–60°F (10°C–15°C), 60%–70% humidity — basements. Sweet potatoes and winter squash. Use shallow racks or perforated trays. Sweet potatoes need curing at higher temperatures and humidity before storing.

The entrance to our root cellar.Photo Twin Oaks Community

Root Cellars

  • Potatoes can be stored for five to eight months with a good in-ground root cellar.
  • Potatoes are best stored in a moist, completely dark cellar, at 40°F (5°C) to 50°F (10°C). Ventilate as needed for air exchange and to keep the cellar in the ideal temperature range.
  • Also for apples, cabbage, or root vegetables, but be careful what you mix, because ethylene from the apples, for example, will cause potatoes to sprout!
  • Some people pack unwashed vegetables in boxes of sand, wood ash, sawdust or wood chips. Perforated plastic bags are a modern alternative.
  • Cabbages or pepper plants can be hung upside down in the cellar to ripen, or simply to store.
  • Celery and leeks can be replanted side by side in tubs of soil.
  • See Nancy and Mike Bubel’s book Root Cellaring to learn how to design, build and use a root cellar.
Using a sturdy digging fork to harvest leeks in December.
Photo Pam Dawling

In-Ground Storage

  • Depending on your winter temperatures, some cold-hardy root crops (such as turnips, rutabagas, carrots, parsnips, Jerusalem artichokes and horseradish) and also leeks can be left in place in the ground, with about a foot (30 cm) of insulation (such as straw, dry leaves, chopped corn stalks, or wood shavings) added after the soil temperature drops to “refrigerator temperatures.”
  • Hooped rowcovers or polyethylene low tunnels can keep the worst of the weather off.
  • There could be some losses to rodents, so experiment on a small scale the first winter to see what works for you.
  • Besides being used as a method for storage of hardy crops deep into winter, this can be a useful method of season extension into early winter for less hardy crops such as beets, celery and cabbage, which would not survive all-winter storage this way.
  • In colder regions plan to remove the crops before the soil becomes frozen, or else wait for a thaw.

Drawing credit WSU Storing Vegetables and Fruits at Home

Harvested turnips ready for storage.
Photo Pam Dawling

Storage Clamps (Mounds)

  • Cabbage, kohlrabi, turnips, rutabagas, carrots, parsnips, horseradish, Jerusalem artichokes, salsify and winter radishes can be stored with no electricity use at all, by making temporary insulated outdoor storage mounds (clamps).
  • Mark out a circular or oval pad of soil, lay down some straw or other insulation, pile the roots up in a rounded cone or ridge shape, and cover them with straw and then with soil, making a drainage ditch round the pile. As a chimney for ventilation, leave a tuft of straw poking out the center. Slap the soil in place to protect the straw and shed rainwater.
  • For the back-yarder, various roots can be mixed, or sections of the clamp can be for different crops. Those growing on a large scale would probably want a separate clamp for each crop. It is possible to open one end of a clamp or pit, remove some vegetables, then reseal it, although it takes some care for it to be successful.
  • There is a balance to be found between the thermal buffering of one large clamp and the reduced risk of rot that numerous smaller clamps provide.

Drawing credit WSU Storing Vegetables and Fruits at Home

 Pits and Trenches

  • Dig a hole in the ground, line it with straw, lay in the vegetables, then cover with more straw and soil.
  • To deter rodents, bury large bins such as metal trash cans, layer the vegetables inside with straw, and cover the lid with a mound of more insulation and soil.
  • Trenches can have sidewalls made with boards to extend the height.
  • You can bury insulated boxes in the ground inside a dirt-floored shed or breezeway. Insulated boxes stored in unheated areas need six to eight inches (15–20 cm) of insulation on the bottom, sides and top.

Drawing credit WSU Storing Vegetables and Fruits at Home

Cherokee Purple tomatoes. Don’t store ripening tomatoes with your potatoes!
Photo Southern Exposure Seed Exchange

Ethylene

  • Ethylene is associated with ripening, sprouting and rotting.
  • Some crops produce ethylene in storage — apples, cantaloupes, ripening tomatoes all produce higher than average amounts.
  • Chilling, wounding and pathogen attack can all cause damaged crops to produce ethylene.
  • Some crops, including most cut greens, are not sensitive to ethylene and can be stored in the same space as ethylene-producing crops.
  • Other crops are very sensitive and will deteriorate in a high-ethylene environment. Potatoes will sprout, ripe fruits will go over the top, carrots lose their sweetness and become bitter.

 

Drawing credit WSU Storing Vegetables and Fruits at Home

Root Crops in November

Root Crops to Plant in Central Virginia in November

We have reached the slow-growing time of year. We have passed our last chance to sow root crops outdoors. Nothing changes fast. Reread Root Crops in October for more ideas, if you are in a warmer climate zone than us. We are in Winter-hardiness zone 7, which has overall minimum average of temperatures of 0° to 10°F (-18°C to -12°C). We are in subzone Zone 7a, with a minimum average temperature of 0° to 5° F (-18°C to -15°C).

In late November, we sow our fourth radishes in our hoophouse. See Root Crops in September for more about our succession of hoophouse radish sowing dates. We sow Easter Egg, and White Icicle. It is too late for us to sow Cherry Belle or Sparkler types – they get too fibrous. This sowing will feed us for the month of February. Unlike the late October sowing which lasts for 8 weeks, this sowing will only be good for 4 weeks.

See Root Crops in September for information on figuring sowing dates for winter hoophouse succession crops (radishes are the example)

Late September in our hoophouse: radishes, scallions and new transplants in the beds on either side. Photo Wren Vile

In early November (around 11/9), we often sow our second of three plantings of hoophouse turnips. We sow Hakurei, Early White Egg, Oasis, and Red Round. These will be harvested 2/25-3/10 (with thinnings for greens from 1/11).

Sometimes we make our second sowing in late October, if we have space available then and want bigger turnips. We may make a third turnip sowing in very early December if space opens up then. The third sowing is only worthwhile if thinned promptly and eaten small, as the plants will start bolting in early March.

See Root Crops in October, for details of thinning and harvesting.

Root Crops to Harvest in Central Virginia in November

Large Smooth Prague celeriac.
Photo Southern Exposure Seed Exchange
Florence bulb fennel. Photo
Southern Exposure Seed Exchange

 

 

 

 

 

 

If you are unsure how soon temperatures will drop in your area, see Weatherspark

Enter your city, airport or zipcode and you’ll get access to helpful graphics on seasonal temperatures, cloud coverage, rainfall, snow, sunshine, humidity, wind, water temperature at nearby large bodies of water. Also tourism, which I had not previously thought of as a type of weather! After that comes an assessment of growing conditions (considered only as days without frost) and growing degree-days, solar energy, and more.

In Louisa County, where we are, the average daily low temperature in November makes a precipitous but erratic slide from 45°F (7°C) to 36°F (2°C), with a small chance of going as low as 24°F (-4°C) by the end of November. Most of our root crops other than sweet potatoes and potatoes can wait to be harvested until late November, but we would rather proceed with harvesting and storing, as the daylight gets shorter and the chance of cold, wet working conditions get higher.

Green kohlrabi.
Photo Small Farm Central

 

We continue clearing root crops outdoors and storing them (in this order): 

  • ·         25°F/-4°C, bulb fennel
  • ·         20°F/-7°C, turnips, winter radish, celeriac
  • ·         15°F/-9°C, kohlrabi, beets (15-20°F/-9 to -7°C, depending on variety)
  • ·         12°F/-11°C, carrots, Cylindra beets
  • ·         10°F/-12°C, parsnips, probably OK to 0°F (-18°C)
  • ·         Horseradish is not killable by cold temperatures, as far as I can tell. But if the ground is frozen, you can’t dig it up.

Wash and store roots in perforated plastic bags under refrigeration, or in a root cellar or other cold storage place.

Our 9/6 sowing of hoophouse radishes will have finished and our second sowing will mature and brighten our meals from 11/6 to 12/25 approximately. Our first sowing of hoophouse turnips (10/15) will produce edible little roots as thinnings later in the month.

See Washing, sorting and storing root crops in Root Crops in September.

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

Other Root Crop Tasks in Central Virginia in November: Long term storage of sweet potatoes and white potatoes

Sweet Potatoes in storage.
Photo Pam Dawling
Sweet potatoes

After curing, store boxes of sweet potatoes at 55-60°F (13-15.5°C), 50-60% humidity. Curing is complete when the skin is undamaged after rubbing two together. If the heating in your curing space is variable, be sure to check several boxes of sweet potatoes closer to and further from the heater. We once had a sad thing happen after a new heater had been installed. We were checking the most accessible boxes only, not the ones at the back near the heater. We got wrinkly sweet potatoes. If your crop is not curing as fast as you hoped, check the temperature, and do what you can with fans to move the air around without blasting directly on any particular box. Also check the humidity and adapt as needed. We found that splashing water directly on the concrete floor of our basement was the most successful method.

 

Restack the boxes (in a rodent-proof storage cage, if you are using an outbuilding).

Peruvian (“white”) potatoes

 

Potatoes stored in crates in our root cellar.
Photo Nina Gentle

Sort white potatoes in storage 2 weeks after harvest. See Root Crops in August

Root Cellar: Cool to 50°F (10°C) after one month, then 40°F (4.5°C), airing once a week or less if cooling not needed. See Special Topic for July

Special Root Crop Topic for November in Central Virginia Vegetable storage without electricity.

  • ·         Meeting the storage requirements of various crops helps maximize their season of availability
  • ·         Some vegetables need to cure before storage and the curing conditions are different from those needed for storage. Curing allows skins to harden and some of the starches to convert to sugars.
  • ·         Many crops may be stored without electricity, perhaps in buildings that serve other uses at the height of the growing season.

  • ·         Washington State University Extension’s Storing Vegetables and Fruits at Home, is a good introduction to alternatives to refrigerated storage, using pits, clamps and root cellars. Drawings below are from WSU Storing Vegetables and Fruits at Home
  • ·         Also old versions of the USDA Agriculture Handbook 66.
Home vegetable storage options, from WSU
Four Sets of Storage Conditions

 By providing storage spaces with 4 types of conditions, 25 crops can be stored.

  • ·         In my chart in Sustainable Market Farming, the Summary column indicates the general conditions needed for each crop, and allocates each crop to one of 4 groups:
  • ·         A= Cold and Moist: 32°F–40°F (0°C–5°C), 80%–95% humidity — refrigerator or winter root cellar conditions. Most roots, greens, leeks
  • ·         B= Cool and Fairly Moist: 40°F–50°F (5°C–10°C), 85%–90% humidity — root cellar. Potatoes
  • ·         C= Cool and Dry: 32°F–50°F (0°C–10°C), 60%–70% humidity — cooler  basements and barns. Garlic and onions
  • ·         D= Warm and Dry to Fairly Moist: 50°F–60°F (10°C–15°C), 60%–70% humidity — basements. Sweet potatoes and winter squash.
Our winter squash storage cage. Photo Twin Oaks Community
Winter squash and pumpkins – storage

We built a rodent-proof cage with wood shelves. You could use shallow crates to avoid handling each individual squash.

In-ground protected vegetable storage. WSU
In-ground storage

Depending on the severity of your winter, some cold-hardy root crops (turnips, rutabagas, beets, carrots, parsnips, Jerusalem artichokes and horseradish) and also leeks can be left in place in the ground, with about 12” (30 cm) of insulation (straw, dry leaves, chopped corn stalks, or wood shavings) added after the soil cools to “refrigerator temperatures.”

 Hooped rowcovers or polyethylene low tunnels can keep the worst of the weather off. There could be some losses to rodents, so experiment on a small scale the first winter to see what works for you. We have too many voles to do this with carrots or turnips.

Besides being used as a method for storage of hardy crops deep into winter, this can be a useful method of season extension into early winter for less hardy crops such as beets, celery and cabbage, which would not survive all winter this way. Access to crops stored in the ground is limited in colder regions — plan to remove them all before the soil becomes frozen, or else wait for a thaw.

Vegetable storage clamp WSU
Storage clamps (mounds)
  • Cabbage, kohlrabi, turnips, rutabagas, carrots, parsnips, horseradish, Jerusalem artichokes, salsify and winter radishes (and any root vegetables that can survive cold temperatures) can be stored with no electricity, by making temporary insulated outdoor storage mounds (clamps).

Mark a circular or oval pad of soil, lay down straw, pile the roots up, cover them with straw and then with soil, digging a drainage ditch round the pile. For ventilation, leave a tuft of straw poking out. Slap the damp soil in place to protect the straw and shed rainwater.

For the backyarder, various roots can be mixed, or sections of the clamp can be for different crops. Those growing on a large scale would probably want a separate clamp for each crop. It is possible to open one end of a clamp or pit, remove some vegetables, then reseal it.

 There is a balance to be found between the thermal buffering of one large clamp and the reduced risk of rot that numerous smaller clamps provide.

WSU vegetable storage in a buried bin.
Pits and trenches

Dig a deep, wide pit (3+ feet deep) in a dry area where water will not stand, lining it with heavy plastic and straw. Alternate layers of vegetables with layers of straw, finishing with straw. Put a loose sheet of plastic on top, (not sealed down). Cover with more soil.

To deter rodents, bury large bins such as (clean) metal trashcans, layer the vegetables inside with straw, and cover the lid with a mound of more insulation and soil.

Or bury insulated boxes in the ground inside a dirt-floored shed or breezeway. A new life for discarded chest freezers! Insulated boxes stored in unheated areas need 6-8” (15–20 cm) of insulation on the bottom, sides and top.

Root Cellars for crops needing cool, damp conditions

  • ·         Potatoes do best in a dark cellar, at 40° – 50°F (5° -10°C). With a good in-ground root cellar, potatoes store for 5-8 months. Ventilate as needed, to maintain the cellar in the ideal range.
  • ·         Below 40°F (5°C) the starches convert to sugars, giving potatoes an unpleasant flavor and causing them to blacken if fried.
  • ·         Root cellars can be used for apples, cabbage, or root vegetables, but be careful what you mix.
  • ·         Some people pack the unwashed roots in boxes of sand, wood ash, sawdust or wood chips. Perforated plastic bags or crates are easier.
  • ·         Pepper plants can be hung upside down in a cellar to ripen, or store. Cabbage can also be hung upside down.
  • ·         Cabbage, celery, leeks can be replanted side by side in boxes or tubs of soil.
Our root cellar for potatoes. Photo McCune Porter
Ethylene

Ethylene is generally associated with ripening, sprouting and rotting. Some crops produce ethylene gas while in storage — apples, cantaloupes and ripening tomatoes all produce higher than average amounts. Environmental stresses such as chilling, wounding and pathogen attack can all induce ethylene formation in damaged crops. Some crops, including most cut greens, are not very sensitive to ethylene and so can be stored in the same space as ethylene-producing crops. Other vegetables, however, are very sensitive to the gas and will deteriorate in a high-ethylene environment. Potatoes will sprout, ripe fruits will go over the top, carrots lose their sweetness and become bitter.