Tips for greater pumpkin yields
When we drive past pumpkin farms and see fields full of big orange fruits or when we find mounds of pumpkins piled up at nurseries and grocery stores, it’s easy to think that pumpkins are the easiest and most prolific of vegetables to grow. Not really.
Jan Sklaroff, of Chester Springs, wrote to me about his experience this year with growing pumpkins. Said Sklaroff, “I wonder if you have any tips on pumpkins. I tried to grow them this year but only now have one. The seedlings are easy to germinate. I find the yield is challenging.”
I can empathize with Sklaroff. For how much real estate pumpkins take up with their giant, wandering vines, they are not like their prolific, quick-maturing cousins the summer squash. Winter squash set so slowly it’s a while before you know what your yield will be. And pumpkins, particularly the giant ones, take a long time to grow to size. At the heart of it, though, pumpkin yield comes down to adequate pollination. If pollination is inadequate, the fruits will be either stunted or misshapen.
Why should pollination be a problem — with such large, showy flowers, shouldn’t that be a slam dunk for bees? How can there be “inadequate” pollination — isn’t it once and done?
When it comes to pumpkins and other cucurbits, there are several reasons why pollination might not be successful. First, the flowers are “monoecious.” That means that there are separate male and female flowers on the same plant rather than each flower bearing both stamens and pistils. Both flower types must be blooming at the same time for honeybees — the primary pollinators of squash — to gather pollen from the male flowers and carry it to the female flowers. And the bees must visit the female flowers as well as the male flowers, or nothing will happen.
To update my facts, I did an online search and discovered that it’s more complex and tenuous than I realized. The website of the Missouri Botanical Gar-
den (http://bit.ly/2y1Bvrr), one of my favorite online gardening resources, listed additional adverse factors. First, a pumpkin plant’s female flowers are open only for one day, and they are most receptive between 9 a.m. and 4 p.m. Second, during this time, “the flower must receive about 15 bee visits for maximum pollination.”
Third, weather is a key factor. High humidity creates sticky pollen which does not transfer well and honeybees do not fly in cool, cloudy weather. Add in the fact that honeybee populations are in decline and it seems a miracle that any squash plants are able to be adequately pollinated.
The good news is that as a back yard gardener, with probably only one or several pumpkin plants, you can hand-pollinate the flowers. All you really need to be able to do is distinguish between the male and female flowers, pick off male blossoms, and tap the pollen from the stamens onto the pistils of the female flowers. This video shows the basics: https://www.youtube.com/watch?v=aYXHIvbL4WM
Learn about bees
“Native Bees: Beautiful, Essential Pollinators” Want to boost your pumpkin and other vegetable and fruit production? Catch the buzz about native bees and how to protect their habitats during a lecture at the Brandywine River Museum of Art on Thursday, Nov. 2, from 6:30 to 8:30 p.m. The lecture will be led by a local native bee advocate, Don Coats, DVM, who will discuss the importance of native bees in our region, the different species of native bees, and how to help protect them through growing native plant gardens and meadows. Attendees will receive a free packet of native milkweed seeds, attractive to both native bees and butterflies. Light refreshments at 6:30 p.m., lecture begins at 7. Admission $5 for members; $7 for non-members; free for Conservancy easement landowners. Register online at brandywine.org/ conservancy/events.