How to Hand Pollinate Tomatoes, Zucchini & Other Crops

April 13, 2013

If your tomatoes, zucchini, cucumbers or other fruiting plants are producing plenty of flowers but very little fruit, pollination may be part of the problem.

Some crops can pollinate themselves with help from wind or movement, while others produce separate male and female flowers and depend on insects or another method of transferring pollen between blooms.

Hand pollination is a simple way to help when natural pollinators are limited, particularly in indoor gardens, greenhouses or sheltered growing spaces.

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Which Crops Need Pollination? Signs Pollination May Be a Problem Tomatoes, Peppers & Eggplant Zucchini, Squash & Cucumbers Watch the Video Parthenocarpic & Gynoecious Growing Fruiting Crops Indoors FAQs Continue Learning

Which Crops Need Pollination?

Plants that produce fruit generally need pollen to reach the female part of the flower before fruit can develop. How that happens varies by crop.

Self-Pollinating Crops

These plants have flowers containing both male and female reproductive parts. Wind, vibration, insects or movement can usually help distribute the pollen within the flower.

Tomatoes
Peppers
Eggplant
Beans
Peas
Strawberries

Separate Male & Female Flowers

These crops produce separate male and female flowers, so pollen must move from a male flower to a female flower for fruit to develop.

Zucchini
Other squash varieties
Many cucumbers
Melons

Important: Seeing lots of flowers doesn't necessarily mean something is wrong. Squash and cucumber plants often produce male flowers before female flowers appear, particularly early in the plant's growth.

Signs Pollination May Be a Problem

If your plants are flowering but fruit isn't developing properly, look for these clues:

Very few bees or other pollinators are visiting the flowers.
You're growing indoors, in a greenhouse or in another protected area.
Flowers repeatedly open and fall without fruit developing.
Small zucchini, squash or cucumbers begin forming but stop growing and shrivel.
Your plants are flowering heavily but producing much less fruit than expected.

These symptoms can point toward poor pollination, although heat, plant stress, nutrient issues and other growing conditions can also affect fruit production.

How to Hand Pollinate Tomatoes, Peppers & Eggplant

Tomatoes, peppers and eggplant have flowers that can pollinate themselves, but pollen still needs to move within the flower. Outdoors, wind and insects usually provide enough movement. Indoors or in protected growing spaces, you may need to help.

Gently shake or tap the plant. A little movement can be enough to release pollen inside the flowers.

Vibrate the flowers. You can gently touch the flower stem with an electric toothbrush for a few seconds to mimic the vibration created by pollinating insects.

Repeat while flowers are open. If you're growing indoors, checking flowering plants regularly can help improve pollination.

How to Hand Pollinate Zucchini, Squash & Cucumbers

Zucchini, squash and many cucumber varieties produce separate male and female flowers. Before hand pollinating, you'll need to know which is which.

Male Flowers

Male flowers grow on a relatively thin stem. Inside the flower you'll see the pollen-producing structure.

Female Flowers

Female flowers have a swollen area directly behind the flower that looks like a tiny version of the mature fruit.

How to Transfer the Pollen

Find an open male flower with visible pollen.

Use a small paintbrush or cotton swab to collect pollen from the male flower.

Gently brush the pollen onto the center of an open female flower.

Alternatively, remove a male flower, peel back the petals and gently touch the pollen-covered center directly to the female flower.

Tip: Hand pollinating earlier in the day, when flowers are freshly open, can make it easier to find receptive flowers and fresh pollen.

Watch: How to Hand Pollinate

Sometimes it's much easier to see the difference between the flowers and the pollination process than to read about it. This video walks you through hand pollination.

See how hand pollination works and how you can help fruiting crops when natural pollinators are limited.

What Are Parthenocarpic & Gynoecious Plants?

When you're choosing cucumber and other fruiting varieties, you may come across the terms parthenocarpic and gynoecious. They describe different characteristics and don't mean the same thing.

Parthenocarpic

Parthenocarpic varieties can develop fruit without pollination. This characteristic can make certain varieties especially useful in greenhouses and other protected growing environments where pollinators may be limited.

Gynoecious

Gynoecious varieties produce predominantly female flowers. Unless the variety is also parthenocarpic, those female flowers still need access to compatible pollen for fruit to develop.

Growing Fruiting Crops Indoors

Fruiting plants can be grown indoors, but some are much easier to manage than others. Compact plants are usually the best place to start.

Tiny Tim tomatoes are a good example. Their compact growth habit makes them easier to manage indoors than large indeterminate tomato varieties.

Peppers and eggplant can also be grown indoors with sufficient light and space. Large vining crops such as cucumbers and melons, along with sprawling squash and zucchini plants, generally require considerably more room and can be challenging indoors.

Growing indoors? Fruiting plants generally need strong light, and without bees or wind you'll also need to pay closer attention to pollination.

Hand Pollination FAQs

Quick answers to some of the most common questions about pollinating fruiting plants.

Do tomatoes need to be hand pollinated?

Usually not outdoors. Tomato flowers are self-pollinating, and wind, insects and normal plant movement are often enough to move the pollen. Indoors, in greenhouses or in sheltered areas, gently shaking or vibrating the flowers can help improve pollination.

How do you hand pollinate zucchini?

Transfer pollen from an open male flower to an open female flower. You can use a small paintbrush or cotton swab, or remove the male flower, peel back its petals and gently touch the pollen-covered center to the center of the female flower.

How can I tell a male flower from a female flower?

On crops such as zucchini and squash, male flowers usually grow on a thin stem. Female flowers have a swollen area directly behind the flower that looks like a tiny version of the mature fruit.

Do cucumbers need to be hand pollinated?

It depends on the variety and growing conditions. Many cucumbers produce separate male and female flowers and rely on pollinators, so hand pollination can help when bees are limited. Parthenocarpic cucumber varieties can produce fruit without pollination.

When is the best time to hand pollinate flowers?

Earlier in the day is usually a good time, when flowers are freshly open and pollen is readily available. The most important thing is to work with open, healthy flowers.

Why are my flowers falling off without producing fruit?

Poor pollination is one possible cause, but it isn't the only one. High temperatures, inconsistent watering, plant stress and nutrient problems can also cause flowers or young fruit to drop.

Ready to Grow Fruiting Crops?

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