Pollination Vegetables

My Squash Plants Only Produce Male Flowers

Squash plant with male flower. Photo: extension.unh.edu

Question: I think something is wrong with my squash plants. They produce only male flowers. 

C. Carmichael

Answer: Just be patient: the female flowers will come.

Squash such as zucchinis and pumpkins, as well as most other cucurbits (cucumbers, melons, watermelons, etc.), produce unisexual flowers—separate male and female flowers—on the same plant. 

Male flower on the left, female, with its swollen ovary, on the right. Photo: http://www.missouribotanicalgarden.org

The two can be readily told apart by ovary in the form of the future fruit (round, long, crookneck, etc.) found at the base of female flowers. Only female flowers. The males have no ovary and produce, of course, no fruit, but are vital as they provide the pollen needed by the female flowers to produce fruit.

Ma Nature produces male flowers first to start to attract pollinators. Producing male flowers requires little energy and they are produced abundantly. Each lasts but a day, but new ones replace them. So, after a few weeks of male-only flowers, pollinating insects such as bees will hopefully have become accustomed to visiting the flowers daily to pick up pollen and nectar. That way, when the first female flowers appear, there’ll be bees ready to pollinate them. 

So … just wait. The female flowers are on their way!

In the Absence of Pollinators

But what if you’re not seeing bees visiting your squash flowers? First, you do have to look in the morning: squash flowers are pretty much morning bloomers. And adverse weather—heavy rain, extreme heat, unusual cold, etc.—can keep bees away. Also, don’t water on mornings when the plant has female flowers … or if you do water, water only the soil, not the blooms. With that female flower only opening for one day, you do not want to discourage pollinators on that one occasion! 

These improperly pollinated fruits were aborted. Photo: J. Allen, uconnladybug.wordpress.com

It takes up to 12 bee visits to properly pollinate a squash flower. If bees are not visiting regularly, you have a problem, as improperly pollinated fruits will abort and drop off.

Hand pollination may be necessary. Photo: sendjoelletter

That’s why hand pollination is useful and may even be necessary. In fact, many gardeners find they obtain earlier and more numerous fruits when they hand pollinate, largely because that way, more pollen is applied and therefore fewer fruits abort. Read Be Like a Bee and Pollinate Your Curcubits to learn how to hand pollinate your squash flowers. 

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

12 comments on “My Squash Plants Only Produce Male Flowers

  1. I’ve got winter squash, and I’ve got blooms. So, I’ll be checking this out this morning. Thank you.

  2. Thank you, you answered my question about the male flowers. I know I didn’t ask it but jt was in my head.

  3. Mine seemed to start producing female flowers first. The fruits seemed to start to develop before the flowers opened.

  4. Beverly O'Brien

    Thank you for your clear advice! My squash plants have been in very large pots with very high quality organic potting soil and liquid starter food since planting in late April. They have given a couple various variety summer squash. But wondering should I be concerned about older leaves that get crispy and spotted. I just carefully with clean paring knife trimmed them off last night and would like your advice on how to green up and stimulate more squash production. Thanks!

    • For better production, just keep up the waterings and fertilize (lightly) every now and then, according to the product recommendations. And do remove older leaves when they start to yellow.

  5. Robert Weaver

    Why Would A Spaghetti Squash Plant Never Get Bloomes? I have two plants that are big and growing like crazy for the past several weeks but not one flower, on either of them. Without flowers there obviously will be no fruit. Any ideas why? The cucumbers right next door have little cukes and flowers galore.

    • It’s probably just a slower to mature variety. Like most vegetables, there are early, mid-season and late squashes. If you live in a short-season climate, you should look for early ones.

      • Robert Weaver

        I hope your right, all I have planted before, even this year, have had flowers on for weeks. These must be different, not sure which seeds they came from. Thanks.

  6. I’ve been very patient, watching these male flower appear for the past month and waiting for female flowers. It’s now the end of August. Still no female flowers. This is a winter squash so I doubt that there’s even time for it to fruit now. Why are my plants producing only male flowers?

    • That’s certainly not typical, but can happen when the weather is excessively hot. Next year, try mulching and maybe watering more: this will keep the soil cooler.

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