Here’s Why Canning Plain Summer Squash is a Terrible Idea

One of my favorite things about home canning is that you can preserve nearly anything. Meat, fruits and of course vegetables. Nothing’s better than opening up a jar of home-canned green beans or tomatoes! But surprisingly, you can’t can just anything, including some seasonal staples.

One fairly notorious veggie that you cannot can yourself at home is summer squash, of any variety, if you just want to can it plain. It’s possible to can winter squash in a number of ways, including plain, but not the summer variety.

I’ll tell you right up front that it’s just not safe, but keep reading and I’ll explain why not as well as how you can work around this issue to can your favorite summer squash varieties at home.

Never Water-Bath Can Any Plain Squash!

I’ve got to be totally clear up front: you should never attempt to water bath can any kind of squash when it is plain. That’s because squashes are low-acid foods, and low-acid foods must be pressure-canned for safety.

This is because only pressure canning achieves the temperature needed, and the thoroughness, to reliably eradicate the germs that can cause spoilage in your finished product.

Just remember that water bath canning is a no-go for any kind of plain squash, the water bath canning methods can still be used for certain recipes that we’ll talk about later.

Plain Summer Squash is Unsafe to Can at Home, Even with Pressure Canning

Now, just because we checked off water bath canning does not mean we can pull out the pressure canner and start processing zucchini, crookneck, and our other favorite varieties.

Here is where summer squash turns so devilishly tricky: even in a pressure canner, summer squash tends to deteriorate into a mushy mass inside the jar during processing, and that can prevent the total, uniform transfer of heat that’s needed to make the contents safe.

Even if you do everything right and follow an allegedly tested recipe for canning plain summer squash to the letter, the risk still exists that your batch will be contaminated, and possibly with the ever-deadly Clostridium botulinum, the same germ responsible for causing botulism.

You Can Pressure Can Plain Winter Squash, But Not Summer Squash

On the other hand, if you have a pressure canner it is entirely possible to safely process and store winter squash varieties like pumpkins, acorn, and spaghetti squash plain.

That’s because these sturdier squashes hold up a lot better than their summer cousins during the canning process, and because they don’t break down into a dense silt you can rely on your canner to heat them through to the appropriate temperature.

The only trick to remember is that prepping winter squashes is likewise important for safety. We’ll talk more about that in the very next section.

Winter Squashes Must Be Cubed, Not Mashed or Pureed

If you want to can winter squash, whatever variety, you must cut it into larger cubes, never mashing or pureeing them.

Remember what I said above about summer squash breaking down into sludge that will prevent even heating? Winter squash doesn’t act that way, but only if you don’t mash it yourself!

Don’t make the mistake of thinking that it’s safe to do so just because it’s nominally safe to can winter varieties with your pressure canner. Improper preparation of approved produce can still result in an unsafe outcome!

The USDA and NCHFP Reversed Its Stance on Canning Plain Summer Squashes

If you have older canning books in your possession, or you’ve just been canning for a while now, you might have a nagging memory about recipes for summer squashes. You might even be able to open your recipe book right to one!

In any case, the reason why you are remembering it differently is because, at one time, things were different!

The USDA and other authorities provided an official recipe for the home, plain processing of zucchini, crookneck, and other summer squash varieties using basic pressure canning techniques.

But something went wrong over time: When the National Center for Home Food Preservation, one of the leading authorities on canning, went looking for these recipes to test and update them they weren’t found…

Rather, the specific documentation concerning processing times wasn’t found, and the NCHFP cross-referenced other reports for canning summer squash varieties and found them to be inadequate.

They tried and tried again to come up with a recipe that would make the canning of summer squash – plain summer squash – safe and palatable but have been unable to do so. And so they have withdrawn the recipes and recommendations for the practice.

Presently, the NCHFP recommends that summer squash be frozen, pickled, or dried for preservation, not canned on its own.

You Can Still Safely Can Summer Squash as Pickles

Now, all is not lost if you want to can summer squash at home, whatever the variety. You can still do so, but you just cannot can it plain. Even better, you won’t even need a pressure canner if you can it as pickles.

This can be done as slices, chunks, or in some cases even spears. Whether you want a tangy dill recipe or a sweet and crispy bread-and-butter, there are plenty of recipes out there that will allow you to substitute summer squash for cucumbers safely.

Using Summer Squash in Relish is Also Okay

Another way to can your own summer squash at home is to process it into relish. Differing very little from pickling recipes, if you would rather use it as a condiment this is a great way to do it, and again no pressure canner is needed.

The NCHFP also specifies that you can swap summer squash varieties for cucumber in any of their tested and approved relish recipes with no worries…

Summer Squash Can Be Added to Tomato Sauces Safely, Too

Yet another viable method for canned summer squash is to add it to tomato juice or sauce. This creates a high-acid environment that’s safe for the preservation of squash.

Obviously, this might not be to your taste but if you are making a pasta sauce base, soup base, or something else it’s a worthwhile technique.