The crossed squash: when last year’s saved seed grew a stranger

21 July 2025 · 3 min read

Of the six squash plants that came up from last year’s saved zucchini seed, four are producing normal dark green zucchini and two are producing something else: squat, pale green fruit with dark stripes, a hard skin at ten days, and a flavor somewhere between a zucchini and an acorn squash. They are not bad. They are also not what I saved.

The explanation was in the neighbor’s yard last summer, eight feet from my bed on the other side of a chain-link fence, in the form of an acorn squash plant. Zucchini and acorn squash are the same species, and bees do not care about the fence. The female zucchini flower I let set fruit for seed was pollinated, at least partly, by acorn pollen, and the seed inside carried both parents. Nothing showed last year because the fruit of a crossed flower looks like the mother plant; it is the next generation, this one, that shows the mix.

So this year the seed squash gets hand-pollinated, and I started the routine the week I saw the first striped fruit. The job happens in two parts. In the evening I walk the bed looking for flowers that will open the next morning: they are fully sized but still closed, with a slight yellow at the tip. I need one female, which has a tiny squash at the base of the flower, and two or three males, which sit on a plain stalk. Each gets a short strip of painter’s tape wrapped loosely around the tip so it cannot open on its own.

At about 6:30 the next morning, before the bees are properly up, I pick a taped male, tear the petals off to leave the pollen-covered center, untape the female, and dab the pollen onto the sticky center of the female flower, using two or three males for one female to be safe. Then I tape the female shut again so nothing else can get in, and tie a piece of yarn around the stem so I know which fruit is the seed fruit. That one stays on the plant until the vine dies back, long after the skin has gone hard, which this year will be sometime in September.

I have done five so far and three have taken. The two that fell off within a week were probably pollinated too late in the morning, after the flower had begun to close. The striped strangers are being eaten; they roast well, and I have kept one growing out of curiosity, with no intention of saving its seed.