Got Pollination Problems? Give Hand-Pollination a Try!

If you’re having trouble with pollination of your melon, pumpkin, cucumber, or squash plants, don’t give up. Give hand-pollination a try.

Hand-pollinate your cucumbers.

How to Hand-Pollinate for More Cucumbers from Bonnie Plants on Vimeo.

If you’re having trouble with pollination of your cucurbit plants, don’t give up. Give hand-pollination a try.

Cucurbits (the family of plants including squash, cantaloupe, watermelon, pumpkins, and cucumber) are notorious for having pollination problems. A short botanical lesson reveals why. Rather than having male and female parts in one flower, like a tomato plant does, cucurbits have separate male and female flowers on the same plant. That means pollen must be carried from one flower to another (male to female) in order for pollination to occur.

Here’s a little more in-depth description of how cucurbits flower: The first flowers on a cucurbit are male, and these may remain on the plant for about a day before falling off. Sometimes, this falling scares gardeners, especially those growing squash, because it seems like blooms are dropping and all is lost. But don’t fear, the female flowers come along soon, and they’re the ones that produce fruit. Female flowers show up on the plant usually a week or two after the male flowers start showing. After that, there should be both male and female flowers on the plant at any given time while the plant’s still blooming.

There are a few ways to distinguish male flowers from female flowers. The easiest way is to look at where the stem meets the flower. On a female, this area will look like small fruit. Male flowers are typically shorter, don’t show immature fruit, and often appear in clusters. Here are a few examples of male and female flowers on cucurbits.

First, some male flowers...

Male and female flowers appear on a cucumber plant.
This well-pollinated cucumber plant is growing a new cucumber. The fruit comes from the female flower, pollinated by pollen transferred from a male flower, like the bright yellow one above. Ideally, pollen is transferred by bees, but if not, hand-pollination is an option.
Zucchini plants have male and female flowers.
These are male flowers on a zucchini plant.

And now for some females...

Female cucumber flowers produce fruit when pollinated.
This is the female flower on a cucumber plant. See the immature fruit at the base, a clear indication of a female flower. This one has probably already been pollinated and the flower is starting to close.
Zucchini plants have male and female flowers.
This is the female flower of a zucchini plant. Due to good pollination, it's producing a nice-sized zucchini.
Female flowers produce fruit on squash plants.
This female flower is on an acorn squash plant.
So here’s the trick. Cucurbits need cross-pollination from male to female flowers, but this requires a little more of nature, namely the bees that pollinate our vegetables. If bees aren’t present for some reason, then fruit either doesn’t appear or it appears small and shriveled up because it’s not well pollinated. At this point, human intervention is necessary, and you'll want to try pollinating your cucurbits by hand. Here is a lesson in hand-pollination using a Straight Eight cucumber plant as the subject.
Use a paintbrush to pollinate cucumbers by hand.
To hand-pollinate a cucumber, dip a paintbrush into the center of a male flower. Some gardeners use a cotton swab instead of a paintbrush.
Pollen sticks to paintbrush bristles.
The pollen sticks to the bristles on the paintbrush just as it would stick to the hairs on a bee's body.
Pollen transfer to the female flower from the paintbrush.
Transfer the pollen of the male flower from the paintbrush to the center of the female flower. That completes pollination by hand.

The method of hand-pollination shown above should work well for all cucurbits. You also can remove male flowers and touch the anther (in the center of the male flower) to the female flower’s stigma (also in the center), or shake the male over the female, to transfer the pollen.

Hand-pollination can help you have a great harvest of cucumbers, melons, pumpkins, and squash. Happy growing!