Today we’re going to dive into the sex life of squash. But it’s not as skeevy as it sounds.
Have you ever wondered why we usually only see the male blossoms of squash (the ones with the long stems) at farmers’ markets? Or why some flowers turn into cucumbers, while others fall off the vine? Or why a corn on the cob will have missing kernels on its end? The answer to all this is pollination — or as I like to call it, flower sex.
As a gardener, I’ve always been fascinated by how all the different plants in my yard flower and then fruit. While we commonly associate the term “fruit” with the fleshy, seedy, sweet or sour parts of plants like apples, oranges, bananas, and berries, in a botanical sense, a fruit is the structure on a plant that disseminates seeds, including ears of corn, bean and pea pods, peppers, and squash.
Some plants, like corn, are self fruitful (or self pollinating). That means they grow with both male and female parts on each plant and don’t need outside interference from a bee or other pollinator to produce fruit. In the case of corn, a stalk has (male) tassels and (female) silks, and needs only wind to shake some of the pollen off the tassels and onto the silks. When this happens, babies happen — in the form of every fertilized silk turning into a corn kernel. (I wrote more about corn here.) Missing kernels on an ear of corn means the silks weren’t fully pollinated, or there wasn’t enough pollen to go around to all the ladies (as sometimes a stalk will have three or more ears waiting to be pollinated).
On the other hand, squash plants (and all other members of the Cucurbitaceae family) can’t produce fruit without the assistance of a pollinator. A squash plant has both male and female flowers on its vines (in plant lingo, this is called a monoecious plant).
In heirloom varieties of squash, the males usually appear first, growing in abundance on the end of long, thin stems. (But interestingly, females will usually appear first in hybrid varieties of squash.) Male flowers tend to be rather large and showy, flaunting their stuff before the females arrive. As in, ahem, other parts of life, the males vastly outnumber the females. If squash could take out personals ads, there would be lots of them from single males looking for females!
Female flowers appear a week or two (sometimes more, depending on climate) after the males, growing low to the ground and close to the vine. They form with what look like baby squash between the flower and the vine; this is in fact the ovary, as the female always bears the baby. The ovary is essentially an immature squash awaiting pollination (fertilization) by the male flower.
If the ovary is not pollinated when the female flower opens in the morning, the flower will close that evening, start to wither, and eventually fall off the vine in a few days. No squash for you.
If a bee does come around that morning, you have to hope that it does a good job of spreading the pollen around so you’ll get a squash. Bees land inside open male flowers to collect nectar and in turn, gather pollen on their bodies. As they buzz around the plant, keeping busy and doing what bees do, they may land inside an open female flower and unintentionally transfer pollen to it. That’s right — your food wholly depends on these little creatures finding your flowers and unwittingly fertilizing them.
Flower sex isn’t all about the birds and the bees though. Successful fertilization depends on temperature, sunlight, hormones, and plant maturity. (See, your plant has to be in the right mood for it, too.)
If there isn’t enough pollen to pollinate the female, the ovary on that flower won’t be fertilized. That means it sometimes takes many bees to pollinate your female flowers and turn them into squash, which is all the more reason to try to attract as many bees as possible to your garden with other beneficial, nectar-rich plants. When bee activity is low, some gardeners will take the extra step of hand pollinating their flowers (by rubbing the anther of a male flower against the stigma of a female flower to transfer pollen) in order to guarantee a crop of squash.
The anther is the reproductive structure in the center of a male flower. It’s the pollen producer.
The stigma is a sticky orange structure in the center of a female flower. Its stickiness is what helps the pollen adhere to it. When pollination occurs, the ovary begins to swell and mature into a seed-bearing fruit. And within a few weeks, we can harvest that squash!
As for the male flowers? Well, if they’re not harvested for food, they die off soon after they open. But there will always be new guys showing up throughout the season.