My cucumber plants are producing a ton of flowers. Should I pinch them off?

Q:

My cucumber plants are producing a ton of flowers—clusters of two or three big yellow blossoms with tight internodal spacing. It seems like a lot to me. Should I pinch some of them off? All of them? Should I be concerned about future pollination if I do?

A:

Cucumber plants that are healthy and growing vigorously under good conditions can develop an excessive number of flowers—far more than the plant can successfully carry through to fruit maturity—particularly, early in the plant’s life. Often, if left to their own devices, the plant will naturally abort a number of small fruitlets, leaving only those that can be supported.

However, flowering/fruitlet pruning depends very much on the type of cucumber you are growing. The small Lebanese or snacker cucumber varieties produce smaller fruit, so growers typically allow two to three fruits to set at each node as the plant can easily support these.

If growing the large, seedless, continental greenhouse types—sometimes called European, Japanese, or English cucumbers, and are the most commonly grown hydroponically—then all the flowers should be female as the plants are gynoecious (that is, they only produce female flowers as pollination is not required to set and produce fruit).

In this case, the small fruitlets, which have flowers attached to the end, would be thinned to one per node. If you are growing the seeded American slicer or other similar large-fruited and seeded cucumbers, then the plants need both male and female flowers for pollination to occur.

Often, early in the life of a seeded cucumber type, it will first produce a large number of male flowers. These are flowers that don’t have the small cucumber fruitlet at the base as female flowers do.

In this case, excessive male flowers can be removed until the first female flowers are seen. Then pollination can occur. For large-fruited, seeded cucumbers, ideally only one fruit per node should be allowed to develop. You can wait until after pollination has occurred and the small fruitlets have started to grow before selecting the largest fruitlet to grow in each node.

A quick side note: Often, not all the flowers will pollinate if there are multiple flowers in each node. (Also, some of these flowers will be male and naturally fall anyway.) If growing in a greenhouse or indoors, there also may not be any insects to carry out the pollination process.

In this case you will need to transfer pollen from the male to the female flowers. Since this is a time-consuming process, most hydroponic growers prefer the seedless/gynoecious cucumber varieties that set seedless fruit without the need for pollination.

Overbearing can be a problem in many cucumber varieties when under good growing conditions. This can lead to the plant become exhausted and aborting flowers and fruitlets later on. So, to improve fruit size and keep the plant cropping for longer, the number of fruit is controlled with fruitlet pruning where required.

Remember that initially, the first few fruitlets on the plant may wither and fall. This is a normal process for many varieties. The plant will set and carry fruitlets further up the vine once this has occurred and it’s no cause for concern.

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Written by Lynette Morgan
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Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from Massey University, New Zealand. Lynette is a partner with Suntec International Hydroponic Consultants and has authored several hydroponic technical books. Visit suntec.co.nz for more information.  Full Bio