how to store garden vegetables for winter

WE TALKED ABOUT storing tender ornamental plants recently, but what about garden vegetables, now that colder nights and days are not so far off? Each year I need to remind myself what stores best where—which is most of all determining what particular combination of temperature and humidity, such as cold and moist versus cool and dry, and so on.

It also takes some experimentation, since our modern homes tend to lack just the perfect place. (Oh, to have a root cellar!) How to store homegrown garden vegetables:

temperature and humidity

MANY VEGETABLES prefer to be stored surprisingly cold, at 32 to 38 degrees F.  Notable exceptions: sweet potatoes (55-60 degrees), and pumpkins and winter squash (50-55, after a week or two curing even warmer).

Many also like it humid (root vegetables and potatoes, for instance—like 90 percent or thereabouts), but others such as onions and garlic and winter squash won’t do well where humidity is so high. By the way: Home refrigerators are usually cold and dry (40°F and 50-60 percent relative humidity), says the University of Minnesota Extension, in their thorough bulletin on vegetable storage.

Various extension services and other experts, such as the Maine Organic Farmers and Gardeners Association, have extensive recommendations, often with charts to simplify things (this one’s from MOFGA, part of a comprehensive pdf):

the basics of storage

VEGETABLES AT PEAK maturity will store better than underdeveloped or over-ripe ones. Delay harvesting as long as possible, presuming it doesn’t mean the vegetable is deteriorating, or animal pests are apt to be gnawing at it.  Root vegetables can enjoy a little or a lot more time in the ground if your garden is pest-free; kale and collards and Brussels sprouts can stand into the frost awhile.

Harvest carefully–don’t bruise or handle things roughly, and set aside any nicked or otherwise imperfect produce to use up first. That includes immature things that might be good enough to use in a soup or other dish right now, but won’t keep. For example, I make soup from any bruised potatoes or onions whose tops stayed greenish as soon as they are dug.

Some things don’t store well no matter when you harvest—tomatoes and peppers, for instance. Freeze peppers at their peak, instead, and whole tomatoes in freezer bags, too, or cook them up into some delicious concoction like easy tomato sauce that freezes well (as do these roasted, herbed tomatoes). You can can tomatoes, of course, as well.

One more basic: There’s no substitute or remedy better than growing a storage variety in the first place. So, for instance, I eat all my ‘Ailsa Craig’ onions first (a variety that is not meant to keep) and store my ‘Patterson’ ones (a rock-hard keeper). Logical, right? Among the species of pumpkins and winter squash, those in Cucurbita maxima (including ‘Blue Hubbard,’ and ‘Lakota,’ ‘Jarrahdale,’ ‘Buttercup’ and many more) are generally the best keepers. This ‘Butternut’ from a local seed company near me was improved over many years of careful selection for storing a long time, so I grow it now. Nothing you can do to make a summer squash last all winter! You get the idea. Choose varieties at seed-shopping season with storage in mind.

extra details by crop

FOR TEMPERATURE and humidity ranges, refer to the chart above or the one below (copyright 1996 by the University of Wisconsin), which is part of a great vegetable-storage factsheet by H.C. Harrison that also includes details about indoor storage room details, outdoor pit-style storage, and more. Some extra tips, besides the temperature and humidity particulars:

Squash and pumpkins: Though different species are better or worse keepers, the general idea: Cut fruits from the vine, leaving stems intact, after the stem is getting corky or at least woody, and the skin is hard and possibly starting to dull. Slightly immature fruits may continue to ripen off the vine, so long as they are not stemless (I leave a piece of vine attached at first, too.) Most need a week or two in a warm, dry, airy spot (about 75-85 degrees) to cure–very important, and a step not to be skipped. Don’t let fruits get cold (below 50) once cured.

Root vegetables (carrots, beets, rutabaga, parsnips, turnips): Leave in the ground as long as possible, perhaps with straw or leaves as mulch on top to insulate. Friends dig theirs gradually, well into winter, by mulching enough to keep the ground unfrozen. When you must dig, trim tops short (without removing the top of the root), cooking the bonus crop up where possible (such as beet and turnip greens). I then store these in the crisper drawers of my refrigerator for the remaining months of winter, which is not really humid enough, but I somehow make do, and the best I have to offer.

Potatoes: Harvest after vines die down, then cure at 50-60 degrees for a couple of weeks (avoiding light) before moving to cooler, humid storage (about 40F or slightly cooler). Some gardeners wrap each cured tuber in newspaper before putting them in storage bins or baskets. If they start to sprout, it’s a sign the temperature is too high.

Sweet potatoes: These are hard to store (and even harder up North, where we get fewer truly mature tubers that are ideal for keeping). Curing fresh-dug sweet potatoes will help their skins firm up, allow any nicks to heal, and also give them time to get sweeter, converting inner starches to sugars. Louisiana State and elsewhere recommend 5-10 days at 80ish degrees after digging and similarly high humidity (80 or even 90 percent), before storing around 55 or 60 degrees.

Garlic and onions:  I grow a year’s worth of garlic from my own “seed,” harvesting in August or thereabouts. I dry the harvest in a warm, dry spot (but not in the sun) for several weeks before trimming the roots and tops, and storing the bulbs cool, dark and airy.  I also freeze some garlic and onions for use next spring and summer, when it would have begun to sprout in storage.

Herbs: I freeze mine in a variety of concoctions. How to freeze herbs.

Other crops: Refer to the charts, or better yet, click the links to the Maine Organic Farmers and Gardeners pdf, the Minnesota extension website, or the one from University of Wisconsin, with its added bonus of dreamy storage-room plans. Some day!

university of wisconsin vegetable-storage chart

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