Hand Pollination of Squash and Pumpkins

by Glenn Kopp and Chip Tynan 


Male and Female Flowers

New gardeners are often surprised to discover that squash and pumpkins have separate male and female flowers on the same plant. These flowers were taken from the same plant but the flower on the left is a male flower and the one on the right is female. Only female flowers will form fruit.

Female Flower with Small Fruit (ovary)

Here a female flower can be seen on the plant. After pollination and fertilization the ovary will develop into a fruit.

Male flowers lack an ovary

Note that the male flower lacks the swollen ovary below the flower petals.

Male flower

Because male flowers usually start to open earlier in the season than female flowers, gardeners often express concern that their plants are not producing fruit. Noting that female flowers are absent can explain the situation.

Opened male flower

Here a male flower has been opened to show the stamen or pollen bearing structure.

Close-up of pollen on anther

The yellow pollen is being released by the anther. It is ready to pollinate a female flower.

Petals completely removed to create the "brush"

Here the flower petals have been removed to make a "brush" that can be used to pollinate a female flower.

Applying pollen to stigma of female flower with the "brush"

The pollen is being transferred to the stigma of the female flower completing the process of pollination. In nature, bees and other insects perform this important procedure.

Ovary begins to swell after pollination and fertilization

After pollination, fertilization occurs and the fruit develops. Fertilization is necessary for fruit formation. If fertilization does not occur, the ovary will wither away. If fertilization is successful, the ovary will begin to swell and a fruit develops. For information on pollination problems: Pollination Problems of Cucurbits