Home & Garden Information Center

Page Last Updated
04-Sep-2007

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This is a male summer squash flower. Only female squash flowers produce fruit. The immature fruits are visible just behind the female flower bud well before the flowers even open.

Squash need to be pollinated by bees in order to produce fruit. As many as 30 bee visits per female flower may be required for good pollination. If pollen is not transfered from the stamen of the male flower to the stigma of the female flower when the blooms are open and receptive, the unfertilized fruits will drop off within a short time after the female flower closes.

If there are no or few pollinators present in your garden, squash fruit will not set. It is possible, although somewhat tedious, to hand pollinate the female flowers in order to ensure production. Use a soft artists paintbrush or cotton swab to pickup the yellow, dust-like pollen grains from the yellow structures (anthers) that protrude upward on stalks inside the male flower. Transfer the pollen to the sticky pale green or white structure (stigma) on top of a stalk in the middle of the female flower. You will need to rub the pollen onto the sides of this structure as well.

Hand pollination must be done fairly soon after flowers open early in the morning. In hot weather blossoms may close before noon. Each blossom only opens once. Once a flower closes, the chance for pollination is past.

Other cucurbit plants such as cucumbers, watermelon and other melons can be pollinated in the same way. Their flower parts and immature fruit are smaller than those of squash, but should still be easy to see.

Karen Russ
Home & Garden Information Center