Save Squash Seeds and Grow the Same Variety Next Year

Last year I saved seeds from what I was pretty sure was a beautiful Delicata squash. Grew them out this spring. What came up looked like a Delicata that had a bad dream about a zucchini. Lumpy, pale, kind of sad. The girls thought it was hilarious. I did not.

That’s the cross-pollination trap, and squash fall into it harder than almost any other vegetable. If you want to save squash seeds and actually get the same thing next year, there’s a little more to it than just scooping out the guts and letting them dry on a paper towel.

Why Squash Seeds Are Sneaky

Here’s the thing most seed-saving guides skip. Squash don’t cross with every other squash. They cross within their species. So a zucchini (Cucurbita pepo) will cross with an acorn squash or a delicata or a spaghetti squash, because they’re all C. pepo. But it won’t cross with a butternut (C. moschata) or a hubbard (C. maxima).

Which, now that I think about it, is actually useful information. Grow one butternut and one zucchini in the same garden and your seeds are totally fine to save. Different species, no problem. But grow two C. pepo varieties and the bees will mix them up without asking your permission.

The cheapest fix is just to grow one variety per species each year. Pick your favorite zucchini, grow only that one, done. That’s my approach now and it costs exactly nothing.

If You Want to Grow Multiple Varieties

You can hand-pollinate and tape the flowers shut. It sounds fussy but it takes about five minutes once you get the hang of it. The night before a female flower opens (it’s the one with the tiny proto-squash at the base), tape it closed. Do the same with a male flower. Next morning, open both, rub the male onto the female, retape the female, and mark it with a bit of yarn so you know which fruit has the pure seeds. Leave that one on the vine to fully mature even after the rest of your harvest is done.

Honestly the first time I tried this I taped the wrong flowers and got nothing. Took me a whole season to figure out male from female. So there’s that.

Let the Squash Get Fully Ripe

This one trips people up. You don’t save seeds from a zucchini you’re going to eat, because eating-ripe and seed-ripe are two completely different things. The seed squash needs to stay on the vine until it’s past the point you’d ever want to cook it. Skin hard, color deep, stem starting to dry out. For most winter squash you’d normally let it cure anyway, so just leave your seed squash an extra few weeks before you crack it open.

Summer squash you’d normally eat young. For seeds, let one get enormous and ugly and basically embarrassing. That’s the one you want.

Scooping, Fermenting, and Drying

Cut the squash open and scoop the seed mass into a bowl. Add water and swish it around. The seeds sink, the stringy gunk floats, and you can pour most of the pulp off pretty easily. Rinse a few times until you’ve got mostly clean seeds.

I ferment my squash seeds for about two to three days, same basic idea as the tomato seed ferment method. It helps break down the gel coating and seems to knock out some seed-borne issues. Not strictly required, but I’ve had better germination rates since I started doing it.

After fermenting, do a final rinse and spread them on a plate or a piece of parchment (not paper towels, they stick), and let them dry somewhere with decent airflow for a week or two. A fan pointed nearby speeds this up a lot. They’re dry enough when you can’t bend them without snapping them.

If you want to check for viable seeds before you pack them away, try the same float test you’d use for other seeds. Floaters are usually duds. Though I’ll admit I’ve had floaters that sprouted just fine, so take that with a grain of, uh, seed-starting mix.

Storing for Next Season

Label them. Write the variety and the year. I can’t stress this enough because I have a whole drawer of mystery seeds that past-me was apparently too busy to label and present-me deeply resents him for it.

Squash seeds store well, usually three to five years if kept cool and dry. I use small paper envelopes inside a glass jar with a couple silica gel packets. The jar goes in a dark cabinet. Total cost of the storage setup is maybe a few dollars and most of it’s reusable year after year. And if you want similar tips on saving seeds from other vegetables, the approach for saving bean and pea seeds is even more forgiving if you’re just getting started with seed saving in general.

The whole point is to stop buying the same packet every spring. A good squash variety is worth keeping going, and once you’ve got the process down, saving squash seeds takes maybe twenty minutes of actual effort per variety. Pretty good return on investment. You could say the savings really squash the cost of buying new seeds every year.

(I’m not sorry.)

Photo by Mohamed Marey on Unsplash