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Deformed cucumber from incomplete pollination, Okra In My Garden

6 Reasons Why Cucumbers are Deformed

It can be frustrating to patiently wait for cucumbers to mature on the vine only to discover that the beautiful produce you longed for is deformed.  When something like this happens, the first question we tend to ask is, what went wrong?  The second question is, what can I do to prevent it from happening again?  In this post, I’ll discuss six reasons why cucumbers do not develop properly and what you can do to prevent it from reoccurring.

1. Cucumber Inadequately Pollinated

Perhaps the number one reason for malformed cucumbers is inadequate pollination.  Female cucumber flowers, which can be identified by the miniature cucumber (ovary) located underneath the bloom, require pollen from the male flowers in order to produce mature fruit.  The primary way this occurs is via pollinators like bees, wasps, hornets, and other insects.  Sometimes there are not enough pollinators present to adequately do the job, and we are left with oddly shaped, inedible cucumbers.  To remedy the problem, simply hand pollinate the flowers by taking a small cotton swab or a small, soft-bristled paintbrush and transfer pollen from the stamen of the male flower to the stigma of the female flower.  Alternatively, you can take the male flower, remove the petals to expose the stamen, and gently brush it against the stigma of the female flower.  Granted, hand pollinating squash, melon, and zucchini plants is easier because the flowers are larger, nevertheless, cucumbers can be pollinated just as successfully.

2.  Weather Conditions 

No one likes hot temperatures, including cucumber pollen.  When the mercury rises, the live pollen count drops because high heat kills pollen.  Thus, when a bee carries pollen from the male flower to the female flower, it may be transporting both living and dead pollen.  And while the pollen transference may have occurred, there may not have been enough viable pollen for the cucumber to be fertilized properly.  The result will be misshapen cucumbers.

Humidity also plays a role in proper cucumber development. When conditions are either too dry or too wet because of rain, the pollination success rate can suffer and in turn, negatively affect cucumber development.

deformed cucumber
Deformed cucumber, Okra In My Garden

3.  Improper Watering

Cucumbers have a high water content, even slightly more so than watermelon (96% vs 92%).[1]  Thus, they require a lot of water to grow properly.  Cucumber plants that are watered inadequately or inconsistently will produce misshapen cucumbers.   Remember, too, that plants growing in pots tend to dry out quicker than plants growing in the ground so keep an eye on cucumbers growing in containers to make sure they receive enough water.

4.  An Imbalanced “Diet”

People aren’t the only ones in need of a balanced diet.  Plants need one, too.  If cucumber plants, which are heavy feeders, are not given a “balanced diet,” their produce will be affected.  Before you plant cucumber seeds or seedlings, amend the soil with mature compost a few weeks ahead of time.   Then add a side dressing as needed throughout the season.  If you are growing in containers, you will probably need to fertilize more frequently.  Be sure to follow package directions when fertilizing container vegetable plants.

While fertilizer is important to cucumber development, too much fertilizer can present a problem. Fertilizers that are high in nitrogen can result in greater vine growth but fewer cucumbers, and the ones that do grow may be deformed.  This is the fertilizer I use.

5.  “Roadblocks”

Cucumbers vines are not static.  They climb, crawl, and wind around whatever is in their path.  Sometimes as the cucumbers are forming, their path may be impeded by other cucumbers, plants, rocks, etc.  One way to encourage well-formed cukes is to minimize the obstacles in their way.  This is best accomplished by growing them on trellises.  Vertical growth can help improve cucumber development.

6.  Insects

Of course, no article about cucumber development would be complete without talking about insects.  Sap-sucking insects in particular can cause cucumbers to curl.  Aphids, whiteflies, leafhoppers, squash bugs, leaf footed bugs, and mealybugs can all cause cucumbers to be deformed.  Usually, these pests can be easily treated with homemade insecticidal soaps and neem oil sprays.  Cucumber development can also be affected by squash vine borer larvae, which develop on the inside of the vines causing nutrients and water to be restricted.  Ultimately, the vine will die.  Although this insect primarily attacks squash and zucchini plants, cucumbers and melons are also on their menu.  Check out the articles for each of these insects for more information on how to identify, treat, and prevent them.

deformed cucumber
Cucumber deformed due to squash vine borer larva, Okra In My Garden

Cucumbers are one of the most popular and enjoyable warm-weather crops to grow.  With just a little attention, they should develop properly, ensuring you have an endless supply all season long!

 Thank you for reading this article!  If you found it helpful, please consider sharing it with others via email or social media!   

[1] Urban Worm Company,, accessed 5-21-21.

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