Zucchini rotting


My zucchini was hand pollinated, but it did not grow big and it was rotting . I would like to know and how to prevent this from happening. When we hand pollinate female flowers, at which part of the stigma , the sides or the top, should be pollinated?

Thank you!


Thank you for contacting the Toronto Master Gardeners about your zucchini. Hand pollination can be very beneficial to improve the harvest for zucchini and other  vegetables in the Cucurbit family eg. squash, cucumbers, melons, etc. It is quite common to have poor pollination in these plants, and there are several possible reasons for this including not enough pollinators, inadequate numbers of male and female flowers,  and unfavourable weather conditions (very cool or very hot, rain at the time of pollination). Hand pollination gives nature a helping hand!

Hand pollination is best done in the morning when the male and female flowers open. It can be done using either a q-tip or paintbrush, or with a male flower from which you have removed the petals to expose the anther. With a q-tip or paintbrush, touch it gently to the anther to pick up lots of pollen, then gently touch all parts of the female stigma, the top and all sides, to transfer the pollen. With the male flower, touch the anther gently to all parts of the stigma.

I think there are a couple of possibilities for the zucchini in your photo. The first is that it could be the result of incomplete pollination. When insufficient pollen is transferred to the female flower, the fruit doesn’t develop properly and it is often left on the vine too long as we hope for it to continue to grow, and it then becomes susceptible to soft rot.

The other possibility is that the zucchini in your photo is a parthenocarpic fruit. This is non-fertilized fruit produced by female flowers. Zucchini tend to develop female flowers before male flowers, so parthenocarpic fruit is often seen early in the season. As with the first possibility described above, this fruit also doesn’t develop normally, we leave it on the vine too long, and it becomes susceptible to soft rot.

Hand pollination can make a huge positive difference to your zucchini harvest, and it’s quick and pretty straightforward to do. Here are a couple of links with more information about how to do it :

Pollinating squash, cucumbers & pumpkins – Niki Jabbour

Hand pollination of squash and corm in small gardens

And here is a link with information about growing zucchini that might be helpful :

Growing summer squash and zucchini in home gardens

Best of luck with your zucchini!

June 28,2021