Be a Pollinator

Did you know hand pollination can improve the fruit set of your squash plants? Summer squash (Cucurbita pepo) belong in the gourd plant family, known as the cucurbits. Many commonly grown garden vegetables, including melons, cucumbers and pumpkins, also are cucurbits.  

Summer squash and most other cucurbits are monoecious, meaning they have separate male and female flowers. For pollination to occur, pollen must be moved from the male flowers to the female flowers. Male flowers are the first to bloom. These pollen-containing blossoms are sent up from the base of the plant on long skinny stems called peduncles. The squash plant produces female flowers second to ensure pollen is present and pollination can occur.  

Squash blossoms require several visits by pollinating insects to complete fertilization. Watch your garden for insect activity. Squash blossoms are only open for a couple days, so these pollinating insects might need help transferring pollen during cool, rainy days. Partially pollinated squash blossoms will result in deformed fruit. The first female flowers to appear on the plant will produce the largest fruit. 

This activity will teach you how to improve your garden’s bounty by hand-pollinating your squash plants.  

Activity Supplies

Here’s what you will need to be a pollinator: 

• Blooming squash plants 

• Hand pruners or thinning shears 

• Rubber bands 

• Paintbrush or cotton swab  

Activity Steps

1. Identify the male flowers on the squash plant. These flowers typically grow on longer, skinny stems and grow upward, instead of closer to the base of the plant. Male squash flowers contain a single anther inside a group of petals. Use a rubber band to close the petals around the anther. This will prevent the flower from losing any pollen.
2. The next day, remove the banded male flowers from the plant with clippers or pruning shears. Take the rubber band off the flowers and gently remove the petals without damaging the anther inside.
3. Identify the female flowers of the squash plant. These blossoms look exactly like the male blossoms, but they will have a large stem at the base of the flower that looks like a miniature squash. In the center, the female flowers will have a three-part stigma.
   
   (Hint: Your plant may only have male flowers at the beginning of the season. Male flowers appear first, and it could be up to a week later before you have any female flowers.)
4. Brush the male anther on the stigma of the female flower, or use a paintbrush or cotton swab to transfer pollen from the anther to the stigma.
   
   ( Hint: If you want to save the seeds from your open-pollinated summer squash, use pollen from the same cultivar and close off the female blossom after it has been pollinated. This will ensure your squash seeds will produce true to type plants that look like the parent plant.)
5. Need a challenge? Try pollinating other plants in the cucurbit family, including watermelon, cucumbers, pumpkins and gourds. Just remember to use melon pollen for melon blossoms and cucumber pollen for cucumber blossoms. Not all garden cucurbits will cross-pollinate.

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