Every seasoned gardener knows the feeling - you’re so excited for your summer squash plants to start producing, and then two weeks later, you’ve eaten zucchini in every possible form and still have squash coming out your ears. Squash plants can be incredibly productive when they hit their peak in summer. If you’re able to preserve all that bounty as the harvest rolls in, you’ll get to enjoy your produce in the colder months too (when you’re no longer sick of zucchini)!
Canning Squash: Only for the Expert Canner
Something about the texture of squash makes it seem like it would can well, and of course we’ve all used canned pumpkin from the grocery store, so it makes sense that we hear a lot of questions from gardeners about home-canning squash. It can be done (see what I did there), but it’s not as simple as with some other vegetables. Because squash is a low-acid food, it isn’t safe to preserve it with water bath canning methods (the most common type of canning) unless you pickle it with a lot of salt and vinegar. Plain squash must be pressure-canned to be safe, and that requires having a pressure canner, a fairly expensive piece of equipment that relatively few home cooks own. Even with a pressure canner, there are no safety-tested recipes to can summer squash like zucchini and yellow squash alone. There are some tested recipes for summer squash combined with tomatoes, which add acid into the equation and help inhibit microbial growth. There are also some tested recipes for pressure-canned winter squash, but we say just grow a type of winter squash that stores well and don’t go through the trouble of preserving it. That is the point of winter squash after all - it keeps for a long time, so you can eat it in winter. (More about that later.)
At this point it’s our duty to also say: You should always, always follow a scientifically safety-tested recipe when canning, and follow it to the T. Lots of tested recipes are available in the USDA guide to canning, which is available in print and online. Incorrectly canned food can foster botulinum bacteria, and botulism is a life-threatening illness. Canning is a great way to preserve food for long-term storage with low energy input, but there’s no room for experimentation or corner-cutting!
Alternative Methods for Preserving Squash
If you’re not ready to make the investment in pressure canning equipment, there are several other easy, low-cost options to preserve your squash harvest.
Freezing is the most common way to preserve squash, and arguably the method with the tastiest results. Properly frozen squash will be closest in taste and texture to fresh. In order to freeze squash, you’ll need to slice it into ½ inch slices and blanch it in boiling water for 2-3 minutes. When done blanching, immediately drain and cool the squash in a bowl of ice water.
Once the squash is cool, allow it to drain thoroughly and then package it in plastic freezer bags or rigid containers with about a half inch of head space. You can also freeze grated zucchini to use in baking. Blanch the grated zucchini for about a minute in boiling water, dunk it in ice water to cool, and then drain. Once it’s fairly dry, package it in pre-measured amounts for whatever recipes you intend to use it in, and freeze. One other tip - it’s a good idea to avoid freezing more than two pounds of food per cubic foot of freezer space per day, to keep from overworking your freezer, and to ensure the food freezes quickly.
Drying can be a great way to preserve squash for future use in soups and casseroles without taking up freezer space. Slice squash into ¼- to ⅛-inch slices and dehydrate for 10-12 hours in a food dehydrator at 120-130 degrees Fahrenheit, until leathery or brittle, then place in an airtight container. If your oven can operate at very low temperature, this can be done in a regular oven as well.
There are also lots of plans available online for low-cost home-built dehydrators, including solar dehydrators that don’t use electricity. To use your dried squash later, re-hydrate it in water for about two hours before sauteing or adding it to a casserole, or just throw the dried squash directly into a soup. If dried until crispy and kept sealed in an airtight container, squash can also make great healthy chips for snacking!
Pickling and Fermenting Squash
We mentioned above that the one way to render summer squash safe for water-bath canning is to pickle it (again, follow a tested recipe if you do this)! But even if you don’t want to go through the trouble of canning pickles, you can preserve squash in the short term as refrigerator (quick) pickles, or for a somewhat longer term by lacto-fermentation. Quick pickles are made with a brine of water, vinegar and salt, and put directly in the refrigerator. It’s a very easy process, with delicious results, and the product will keep for about a month in the refrigerator.
Lacto-fermentation is the process by which traditional pickles, kimchi and sauerkraut are made, and essentially involves submerging vegetables in a salt water brine and allowing them to sit at room temperature for a few days, harnessing naturally-occurring bacteria to convert sugars in the vegetables into lactic acid. Fermentation might sound scary, but it’s generally easy to tell if the process has gone wrong, unlike with contamination in canning. If your ferment has gotten contaminated, you’ll notice mold, strange colors, or off smells. If the jar looks mold-free, and smells fresh, tangy, and delicious, it’s probably safe. Both quick pickling and lacto-fermenting squash will produce a crunchy delicious snack, but fermentation may produce more complex flavors and will keep longer in the fridge, up to six months under optimal conditions.
Storing Winter Squash
So far we’ve focused mostly on summer squash, which need to be eaten or preserved shortly after harvest, but there is another type of squash that is intended for long storage - winter squash. Summer squash like zucchini have been bred for harvest at the immature stage, when the fruit is small and thin-skinned, while winter squash varieties were bred to be most delicious when grown to full maturity, when the fruit develops a thick, hard rind and starts to lose water content. At this stage, it becomes much less susceptible to rot.
Different varieties keep for different periods of time, so choose carefully if you want to have squash all winter long. One of the shortest keepers is Acorn squash, which will last about 2-3 months. Delicata is a medium storage quality variety with about a three month lifespan, while Hubbard and Kabocha types last around five months. Butternut lasts the longest, up to an impressive six months. The long-storing winter squashes, such as Butternut, Hubbard and Kabocha, actually get sweeter when stored for a while before eating. Harvest one of these and cook it straight away, and you may find it to be a bit watery and flavorless. Butternut squash needs the longest curing period - it tastes best after about two months of storage. If it’s holiday pies you’re after, some pumpkins, such as Connecticut Field pumpkin, can also store well, up to three months, but the longer lasting varieties of winter squash also make excellent pies. In fact, much of the canned “pumpkin” you find in the grocery store is actually Butternut squash!
Successful winter squash storage begins with proper harvest. Wait until the fruit is completely mature and the rind becomes difficult to scratch or dent with a fingernail, usually around 55 days on the vine. Cut the squash from the vine with 1-2 inches of stem left on the fruit, to minimize the chance of microbes infecting the fruit during the curing process. All winter squash should be cured for 5-7 days outdoors in the sun or inside a warm greenhouse after cutting them from the vine, to allow the stem and any scrapes to heal over before they are brought inside for storage.
Storage conditions also play a big role in successfully keeping winter squash. The optimal temperature is about 50-55 degrees Fahrenheit, with about 50-70 percent humidity. Oftentimes an unfinished basement provides this environment, but never put your squash directly on the floor, and make sure they’re protected from marauding rodents! Squash stored at higher temperatures will last for proportionally shorter periods. Check on your squash often and remove any individuals that have begun to rot, before the infection spreads to their neighbors. Also, never keep winter squash (or other storage vegetables, for that matter) near fruits such as apples and pears, which release ethylene gas, which can cause other food to spoil more quickly.
Now you’re armed with the knowledge to turn that accumulating pile of zucchini in your fridge into winter meals, and take advantage of the magic of natural winter squash preservation! Explore the diversity of heirloom summer and winter squash varieties in our full selection of squash seeds.