Flower Fail: Blossoms Aren’t Pretty When Zucchini Won’t Fruit

Having trouble growing zucchini in your garden? Here's one possible reason why you're getting a small yield of this popular summer squash.

Zucchini Plant

Zucchini Plant

Zucchini plants pump out squash and edible blossoms.

Photo by: Julie Martens Forney

Julie Martens Forney

In this feature, garden authority Gayla Trail, the creator of YouGrowGirl.com, answers frequently asked questions and offers gardening advice.

QUESTION:

My zucchini have beautiful blossoms but they fall off with no fruit. If fruit do develop, the little things rot away. I end up with only one or two zucchini per plant. This happens every year. I water constantly. Why does this happen?

ANSWER:

Sounds to me like you are doing everything right. Zucchinis need more water during the fruiting stage, so you’re on the right track unless you are quite literally watering constantly! Based on your description I’d say that the reason your plants aren’t setting fruit is because they are not being pollinated. This can be caused by a lack of pollinators or simply because the pollinators aren’t moving between flowers and transferring the pollen.

Most common garden plants produce flowers that have their male and female parts crammed into one. However, the reproductive processes of squash plants are separated into distinctly male and female flowers. A pollinating insect must transfer the pollen from the male flower to the stigma inside a female flower for fruit to develop. The fruit then develops from the female flower only. Squash plants tend to produce loads of male flowers early in the season, sometimes well before the first females start to show up. This can account for what appears to be a fruit set problem early on. The male flowers are useless until the females arrive, but they are delicious stuffed with ricotta cheese and fried in batter!

Since you have described what sounds like immature fruit dropping off, I’d say that your plants are producing females, but are not being properly pollinated. The solution to your dilemma is to hand pollinate the female flowers with the males. It’s simple. Here’s how.

How to Hand Pollinate

The first thing you’ll need to do is identify the male and female flowers. Males have a straight, thin stem just behind the petals. They contain the anther inside, which should be loaded up with powdery, yellow pollen. Females are easily identified by a tiny, immature zucchini fruit (or ovary) that sits just behind the petals. Depending on the variety, it sometimes looks more like a thickened stem than a fruit.

Zucchini flowers tend to open up wide in the morning and are often closed by the afternoon so it is important to hand pollinate in the morning. Pluck a fully open male flower from the plant. Peel off the petals to expose the pollen-heavy anther. Gently brush the pollen over the stigma of a fully opened female flower. That’s it! Over the next few days you should see the small zucchini begin to swell and grow into a fruit. Harvest when it is about 3-6 inches.

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