Why The First Cucumber And Squash Blossoms Don’t Set Fruit

It’s exciting when the season’s first huge squash flowers and small cucumber blossoms begin to open because fruit can’t be far behind, right? Well, not so fast. Gardeners anxious for the first signs of harvest are often disappointed when the first blossoms drop, with no fruit formed. There’s a reason the first blossoms of squash, cucumber, pumpkins and melons don’t set fruit.

These crops are members of the Cucurbit family, and two different types of flowers are formed on each plant: separate male and female flowers. Some plant types, like tomatoes, have male and female parts all within the same flower, making all flowers the same. (Bees aren’t needed for tomato pollination; wind accomplishes the task.) But on cucurbits, male parts are in male flowers, and female parts are in separate female flowers, all on the same plant. Bees transfer pollen from the male flowers to the female flowers, and the process of forming a fruit begins.

Male Squash Blossom
Female Squash Blossom

At first glance, the male and female blossoms look the same – nice bright yellow flowers tucked within the vines. But on closer examination, you can distinguish the male blossoms from the female, because in the case of squash, the female blossom has a small squash-looking enlargement at the base of the showy flower petals. A female cucumber has a tiny cucumber at the petal’s base. Male flowers don’t have these, and petals are attached to a bare stem instead.

Male squash blossom on left, Female blossom on right

If you take a really close look inside each flower, you can see the pollen-bearing structure inside male flowers, and the smooth pistil inside females. But the outer structures are the most easily noticed.

What does that have to do with no fruits resulting from early cucurbit flowers? The first flowers formed on cucurbits are almost always entirely male blossoms. They soon whither and drop off – no fruit formed. However, it’s not long before female blossoms start forming along with more male flowers. Then the plants are in business. With both flowers present, bees accomplish pollination, and we’re well on the way to harvest.

So now if it appears something is going wrong with early flowers, there’s no cause for alarm. It’s just one of nature’s interesting foibles.

Happy Gardening!

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