Q: My zucchini plants are producing plenty of flowers, but no squash. Sometimes they start to grow little squashes but then the babies turn yellow to brown, get all wrinkled, and fall off. What’s wrong?
A: It’s highly likely the problem involves zucchini sex.
All squash plants (and related crops such as cucumbers) produce two kinds of flowers, male and female. Here’s how to tell them apart:
The male flower has a long stem, while the female flower has a tiny squash at its base, and a shorter stem.
In order to produce fruit (to a botanist, squashes and cucumbers are really fruit), pollen from the male flower must be transferred to the female flower. Normally, bees do this sort of thing. However, bees haven’t been doing so well lately. There’s a mysterious disease ravaging the hives, and population numbers are down. Also, if the weather is extra rainy, or your plants are under plastic or polyester row covers—or if you’ve sprayed a broad-spectrum insecticide—bees may not be up to doing their job. Pollination is either incomplete, or not happening at all. In this case, it’s up to you.
Zucchini plants only produce male flowers to start with. If you don’t see fruit setting after those first blooms, that’s normal. But once you can identify female flowers, you should start getting squash. If not, here’s what to do.
Make sure you have both male and female flowers available. They should be newly-opened, not at all fading or wilted; early morning is best. Pick a male flower and carefully remove all the petals. That little structure inside is the stamen. The tip (called the anther) contains pollen. (Most kinds of flowers have more than one stamen, but in squash they’re all fused into one lump.)
Now look at the female flowers, shown at left (also notice the developing zucchini with a flower still attached to the end). They have little squiggly bumps inside the petals. Those are stigmas. Your goal is to transfer pollen from the male stamen to the female stigmas. You can use a cotton swab or paintbrush, but it’s easier to just dust the anther over the tips of the stigmas. Stigmas are somewhat sticky, and the pollen will adhere. One male flower can pollinate two or three female flowers.
There, you’ve done it. That wasn’t too hard, was it? Next, you’ll be looking for some unsuspecting neighbors to inundate with extra zucchini!
Article and photos by Leslie Holzmann, Certified Colorado Gardener