I talked about fruit in this article. Now we will take on the vegetables, even the ones that are technically fruits. The entire Cucurbitaceae family, including pumpkins, winter and summer squashes, cucumbers, and unusual European or African squashes that most of us in the Western Hemisphere are not familiar with, are technically fruits. More fruits that act like vegetables can be found in the Solanaceae family, with tomatoes, tomatillos, and cherry tomatoes, of course, but also eggplant, peppers and chili peppers, as well as potatoes (which are not at all a fruit), although this family also contains many beautiful flowering plants. A few unusual examples of fruits that act like vegetables are plantains and avocados.
Traditionally, a vegetable is any plant part that is eaten without seeds, so the stem of celery, the leaves of lettuce, the roots of carrot, and so on. While leeks are considered leaf sheaths and asparagus is a stem shoot, and celery is the stem of a leaf, we shall leave the rest of the delineation between plant parts to the botanists and turn to storing our delicious produce.
For the purposes of storage, produce can be divided into three or four categories: some likes it cold and moist (32°-40°F with 95% humidity), some likes it cold and dry (32°-40°F, 60-65% relative humidity), and some likes it cool and dry (50-60°F and 60% relative humidity) A crucial few, like tomatoes and cucumbers, like it cool and moist (50-60°F with 95% relative humidity). The trick is to figure out which category your vegetable falls into, and how to provide for its needs in your home refrigerator (unless you are otherwise going to preserve it).
I am assuming, for this article, that you don't care to bury a 20 gallon trash can, as Washington State University and the University of Iowa suggest, to store your cold dry root vegetables, and that you don't you already have a root cellar. The University of Wisconsin gives you plans to construct indoor and outdoor root cellars! If you go to these university's websites, you will find far longer storage times than the ones I have given in my chart below. On the other hand, most CSAs give far shorter shelf lifes. This is because they are each making different assumptions about your storage facilities. The universities are thinking that your cold and moist actually IS 31°-40°F, 95% relative humidity. The people writing the blogs are mostly speaking to people whose cold and moist is a crisper drawer.
Many modern refrigerators have more than one crisper drawer (I am told) with adjustable humidity levels. Boring although this next step sounds, Alanna Kellogg, writer of A Veggie Venture blog, suggests that you find an accurate thermometer and test the microclimates of your refrigerator. This is an excellent suggestion. Does this drawer sometimes fall below freezing, while that one is consistently warmer? Explore the potential of your fridge, so you can use it to your best advantage. And if you have an extra refrigerator, by all means set it to cold and moist: (31°-40°F, 95% relative humidity. There are several ways to increase the relative humidity of your refrigerator. One is to wrap dry produce in a clean damp kitchen cloth, then in a plastic bag. Never leave damp produce in a sealed plastic bag for very long—it will get slimy and yucky. You need the towel to absorb excess moisture.
You might want to get a supply of brown paper bags. I use brown paper lunch bags. Here's a blog whose writer agrees with me so I'm including it! I have found that in just about every case, washing vegetables before storing them shortens storage time, because you introduce bacteria and provide a lovely damp environment for them to grow in. Leave it dirty until just before you plan to use it. If you must wash a vegetable, maybe lettuce for instance, dry it thoroughly before returning it to the refrigerator. My mother washes lettuce the morning she plans to serve it and then wraps layers of lettuce leaves, still damp, in cotton dishcloths, to unwrap right before serving. (She learned this from her mother-in-law, my paternal grandmother, who was born in 1906!)
As for the fresh corn question, when I was growing up, we spent at least two weeks every summer at my aunt and uncle's organic vegetable farm in Northern Virginia. The only vegetable they were unable to grow organically was sweet corn—it was a big wholesale crop for them. I remember watching teams of workers picking corn in pre-dawn hours, hustling bushel baskets of fresh-picked, still-dewy corn into the large walk-in cooler. In those days, my answer to "how long can sweet corn sit out" would have been "no time. It must be rushed to the nearest refrigerator. The sugars that make it 'sweet corn' are turning into starch!"
Since then, I confess, I've eaten a lot of supermarket corn, and been accused of, er, vegetable snobbery. So I now say, "refrigerate your sweet corn as soon as possible and eat it as soon as possible." Corn can be successfully frozen, on or off the cob; read about it here. Corn can be stored (if you must) 2-3 days in your cold, moist refrigerator. The damp dishcloth idea might work here, or a paper bag, or even a plastic bag if the corn is still safely clothed in its husk. I am NOT a big fan of plastic bags. The idea is to create a moister microclimate than normally exists in your home refrigerator, but never one that is hospitable to bacteria, slime or mold.
As for avocados, treat them as you would treat any other stone fruit, or as you would treat a tomato. Let them sit on the counter until perfectly ripe and then eat them. They cannot really be stored more than a day or two once they are ripe, as they become gritty. I wouldn't put one in the fridge, and that advice comes from my father, who had an entire avocado almost every day of his adult life. Store mushrooms either in the container they came in or in a brown paper bag placed inside a plastic bag.
The paper bag absorbs moisture and the plastic bag increases the humidity. That is precisely the principle involved in these newish type of vented food containers from Rubbermaid or Tupperware. Apparently you set the vents for exactly the humidity levels the vegetable you're storing requires, and the produce lasts three times longer than it would ordinarily. Now that I've heard of these containers, I definitely want to check them out for myself, and I'm sorry I didn't do it before writing this pair of articles! I've ordered them already.
The chart below is based on information from the University of Minnesota. as well as from from the University of Missouri; both sites seemed to understand that the ideal "cold, moist" was probably not attainable. I've added in some information from Alanna Kellogg's blog and others'. "Treat herbs as you would flowers" suggests Chris Blanchard of Rock Spring Farm in Iowa, which is excellent advice. I've had basil root on my counter in its glass of water—ta da, a whole new basil plant! I've also incorporated information from a few other CSAs' sites—Angelic Organics and my cousin's farm in Virginia, Potomac Vegetable Farms. I am pleased to see that my cousin agrees with me about almost everything—don't put ripe tomatoes in the refrigerator; they'll get mealy. Don't wash anything until right before you use it. Don't put basil in the fridge; it will turn black. She and I, we share 25% of the same genes.
Oh, and click here for all the Dave's Garden articles on preserving food.
COLD AND DRY
(32°-40°F, 65% RELATIVE HUMIDITY)
not really useful for anything, even onions and garlic, and you could refrigerate onions, but these are likely the conditions you will find in an ordinary fridge like mineideal shelf life
COLD AND MOIST
(31°-40°F, 95% RELATIVE HUMIDITY)
a special refrigerator set to these conditions, or a spot in your fridge that is "cold and moist"ideal shelf life
COOL AND DRY
(40°-50°F, 65% RELATIVE HUMIDITY)
a cool counter out of the sunideal shelf life onions (cure at room temp. 2-4 weeks, do not allow to freeze)
asparagus, (store upright with the ends in 1 inch of water for maximum crispness) (hard to imagine) 2 weeks
basil, and other fresh herbs, treat like a cut flower, i.e. trim bottom leaves, insert stem in glass of water, change water frequently,
do not refrigerate basil and other tender herbs!5 days, longer if it roots in the water
green beans (don't store below 40°F)
cucumbers in a paper bag, a few days in fridge ok but do not store below 40°F, or with ethylene gas producers1 week beets (w/out tops) 5 months
eggplant in a paper bag, a few days in fridge ok, deteriorates if stored a long period below 50°F 1 week broccoli2 weeks
peppers in a paper bag, a few days in fridge ok but deteriorates below 45°F brussel sprouts
pumpkins (before frost) do not allow temp. to fall below 45°F 2 months
summer squash, zucchini, in a bag, a few days in fridge ok but do not store in fridge for more than 4 days carrots (without tops)
tomatoes, ripe, do not refrigerate, texture will deteriorate!5 days
celery (store upright with the ends in 1 inch of water for maximum crispness)
potatoes (keep in dark,
cure at 50-60°F for 14 days, will 'sweeten' below 38°F, do not store near onions) 6 months
winter squash (before frost)
avocados (affected by ethylene gas)
3-4 days, unless very hard
kohlrabi (without tops)
garlic cure until dry then store at 50-60°F 3-4 months
mushrooms (store in original sealed container, or, if loose, store in paper bag inside a plastic bag, absorb flavors of strongly smelling food))
depends on variety
parsnips (without tops, after a frost, but do not allow to freeze)
green tomatoes (individually wrapped in newspaper, not touching each other)6 weeks?
radishes (without tops)
turnips (after frost)
photographs courtesy of morguefiles.com, and of Potomac Vegetable Farms, Incorporated, whom I thank kindly.