Root Cellar Temperature-Humidity Chart

How long can certain vegetables be keep in the garden soil before the cold weather demands their removal indoors? Generally, the less susceptible they are to frost, the longer you can keep the vegetables in the ground by using a 12-18-inch covering of mulch. You might consider building a two-to-three foot wall all around the garden to keep the cold winds off the plants during this period that you are stretching their garden life. This will also keep all your mulch from blowing away. The wall can even act as a solid foundation for a temporary greenhouse frame that you could quickly erect and drape with inexpensive plastic film, to keep the plants in their garden soils even longer.

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Kali S Winters

Table 1

Fruits & Vegetables that require cold, moist conditions

Temperature (oF) Relative Humidity (%) Length of Storage
Asparagus 32-36 95 2-3 weeks
Apples 32 90 2-6 months
Beets 32 95 3-5 months
Broccoli 32 95 10-14 days
Brussels Sprouts 32 95 3-5 weeks
Cabbage, Early 32 95 3-6 weeks
Cabbage, Late 32 95 3-4 months
Cabbage, Chinese 32 95 1-2 months
Carrots, mature 32 95 4-5 months
Carrots, immature 32 95 4-6 weeks
Cauliflower 32 95 2-4 weeks
Celeriac 32 95 3-4 months
Celery 32 95 2-3 months
Collards 32 95 10-14 days
Corn, sweet 32 95 4-8 days
Endive, Escarole 32 95 2-3 weeks
Grapes 32 90 4-6 weeks
Kale 32 95 10-14 days
Leeks, green 32 95 1-3 months
Lettuce 32 95 2-3 weeks
Parsley 32 95 1-2 months
Parsnips 32 95 2-6 months
Pears 32 95 2-7 months
Peas, green 32 95 1-3 weeks
Potatoes, early 50 90 1-3 weeks
Potatoes, late 39 90 4-9 months
Radishes, spring 32 95 3-4 weeks
Radishes, winter 32 95 2-4 months
Rhubarb 32 95 2-4 weeks
Rutabagas 32 95 2-4 months
Spinach 32 95 10-14 days

Table 2

Vegetables that require cool, moist conditions

Temperature (oF) Relative Humidity (%) Length of Storage
Beans, snap 40-50 95 7-10 days
Cucumbers 45-50 95 10-14 days
Eggplant 45-50 90 1 week
Cantaloupe 40 90 15 days
Watermelon 40-50 80-85 2-3 weeks
Peppers, sweet 45-50 95 2-3 weeks
Potatoes, early 50 90 1-3 weeks
Potatoes, late 40 90 4-9 months
Tomatoes, green 50-70 90 1-3 weeks
Tomatoes, ripe 45-50 90 4-7 days

Table 3

Vegetables that require cool dry conditions.

Temperature (oF) Relative Humidity (%) Length of Storage
Garlic 32 65-70 6-7 months
Onions 32 65-70 6-7 months
Table 4

Vegetables that require warm dry conditions.

Temperature (oF) Relative Humidity (%) Length of Storage
Peppers, hot 50 60-65 6 months
Pumpkins 50-55 70-75 2-3 months
Squash, winter 50-55 50-60 2-6 months
Sweet Potato 55-60 80-85 4-6 months

Additional Tips:

  • ·Apples: I don’t foresee growing these, but they’re considered the ‘queen’ of storage fruits.
  • ·Beets: good keepers. The ‘Long Keeper’ variety is just that — a great keeper. The leaves are vitamin-rich. Can last 4 to 5 months in storage.
  • ·Brussels sprouts: might keep 4 to 5 weeks if kept in perforated plastic bags. This reminds us we might want to stock up on plastic grocery bags for this purpose.
  • ·Cabbage: if it splits, it won’t keep.
  • ·Chinese cabbage: can last up to three months. You can even replant them in a box of soil in the root cellar.
  • ·Carrots: a summer planting is best for winter keeping. They are the backbone of any food-storage plan. The roots are rich in vitamin A and they can last several months in storage. With adequate mulching, you can even keep them right in the garden row for the winter.
  • ·Cauliflower: keeps only a short time at best, two to four weeks.
  • ·Celeriac: a good keeper.
  • ·Celery: see how late you can keep this in the garden, and then maybe you can get a month or two of storage out of it.
  • ·Garlic: needs lower humidity than root vegetables. If you can find a cool, dry place, it can last seven or eight months.
  • ·Horseradish: very hard and a good keeper.
  • ·Jerusalem artichoke (sunchoke): can last several weeks in plastic bags or in damp sand.
  • ·Kale: high in vitamin content, easy to grow, extremely cold-hardy.
  • ·Kohlrabi: the leaves are good to eat. Packed in damp sand or sawdust, it can keep well into the winter.
  • ·Leeks: especially cold-hardy. Can make it through a winter outdoors if well mulched, or you can plant some in your root cellar in tubs of sand or soil.
  • ·Lettuce: has a short storage life.
  • ·Onions: seed-grown onions are especially good for storage.
  • ·Parsnips: these are perhaps the hardiest of all root vegetables. Be sure to dig them out. If you pull them, you can lose half the root. If you nick the roots with the shovel, don’t store them. Nicks and blemishes invite spoilage, and this applies to all root vegetables. For longer storage, pack them in damp sawdust. Leaves, moss, or sand will work well too. The leaves are edible.
  • ·Sweet Potatoes: the roots are vitamin-rich, and they can keep several months if stored well. Must be cured.
  • ·White Potatoes: beware of planting the kind you buy in the store — they may contain disease. Cool nights promote storage of starch, making for a longer-keeping potato, so the later-maturing ones are best for storage. Must be cured and kept in a dark spot. They can last four to six months.
  • ·Pumpkins: those that have lost their stems won’t keep well.
  • ·Winter radishes: they’ll last until February if well stored.
  • ·Rutabagas (Swedish turnip): will last two to four months in storage.
  • ·Squash: if it’s well stored, it will keep for up to six months. Cure them for 10 to 14 days. Like pumpkins, keep them dry and moderately warm.
  • ·Tomatoes: late-planted tomatoes are best for storage.
  • ·Turnips: these are among the hardiest of vegetables. In storage they might put out pale, leafy tops, good for stews.

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