The Sex Life of Squash

The sex life of squash

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!

Male squash blossom emerging

Male squash flower on long stem

Male squash blossom

Showy male squash blossom

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.

Female squash flower emerging

Ovary on a female squash flower

Female squash blossom emerging

Female squash flower with ovary

Female squash blossom

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.

Non-pollinated female squash flower

Unfertilized female squash blossom

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.

Bee on squash flowers

Pollen on a bee

Bee gathering pollen from a squash blossom

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.

Anther on a male squash blossom

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!

Stigma on a female squash flower

Stigma on a squash blossom

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.

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July 16 2014      33 comments     Linda Ly
Jardín   Verduras

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  • spring

    So glad you posted this! This is my first year of growing squashes and my plants are full of flowers. I would have been disappointed if we didn’t get any pumpkins for Halloween.

    • http://www.gardenbetty.com/ Linda Ly

      I hope you get lots of them!!

  • Sarah

    I love how your posts are always so packed full of useful information :) So what are the flowers that are usually eaten? Male or female or both?

    • http://www.gardenbetty.com/ Linda Ly

      We usually eat the male flowers since there’s so many more of them (and we don’t have to sacrifice any fruit). But occasionally, farmers’ markets will sell the female flowers with baby squash still attached.

  • http://belongwithwildflowers.com/ Caitlin

    This is a great post! I briefly read about the sex life of squash when I was dumbfounded why all my squash plants weren’t producing fruits. I loved this in-depth coverage of the process… thank you!

  • http://www.fiveofmine.com/ Xochi Navarro

    I LOVED reading this! Great pics and description, thanks Linda!

  • Almostfarmgirl.com

    Is it weird that I find this crazy interesting? After reading this, I’ve been plotting all day on how to attract more pollinators…

    • http://www.gardenbetty.com/ Linda Ly

      Not weird at all, I geek out on this kind of stuff all the time! The process of pollination fascinates me.

      In my garden, the bees are most attracted to flowering herbs. I have a small bed of basil that grows year round http://www.gardenbetty.com/2011/05/african-blue-basil/ and at any given time, there are dozens of bees hovering over those three (large!) plants. They also love flowering rosemary, parsley, cilantro, dill, and thyme. Some of these herbs are perennial while others are “wild,” as I let them reseed every season.

    • James Doe

      Now I’m going to go play with my squash’s private parts!

  • http://monkeyandapickle.blogspot.com/ Ashley

    I have had this problem all year with my squash! I guess I don’t have enough bees :(

    • http://www.gardenbetty.com/ Linda Ly

      This year I had sunflowers growing near my squash to up the bee activity. Flowering herbs (basil, parsley, cilantro, dill) also attract them.

  • http://seedsclub.averagepersongardening.com Mike the Gardener

    Wonderful and in depth post. I love the photos. I would also like to add, that you have a better chance of proper pollination if you have multiple plants. This way a bee can jump from flowers on one plant to another and increase chances of fruit … same plants of course.

    • http://www.gardenbetty.com/ Linda Ly

      Agreed! More flowers = more bees.

  • Cary Bradley

    Great discussion. I wonder if the female flower only opens for that one day. Interesting to ponder.

    • http://www.gardenbetty.com/ Linda Ly

      As far as I know, the female flowers only open once. The males may open a second time before they die, but the pollen won’t be viable. Such a game of chance and luck, huh? Once I learned this, it made me truly treasure the squash I DO get!

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