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Bitter Tasting Crops

by Don Janssen, UNL Extension Educator

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Mild bitterness in zucchinis or cucumbers is not uncommon and can be caused by environmental stress like high temperatures, drought, wide swings in temperatures, or uneven watering practices that tend to concentrate cucurbitacins in the fruit.

Vine crops including cucumbers and zucchini produce chemicals called cucurbitacins, which give a bitter taste to the fruit. In cultivated cucumbers and zucchini these chemicals are normally in such low concentrations that we can't taste them. Wild cucurbits contain much higher levels of cucurbitacins, making them inedible to mammals.

This mild bitterness in garden squash or cucumbers may not be so severe as to prevent gardeners from using the fruit. With a mild bitterness due to environmental conditions you would expect all plants in the garden to show the same problem to some extent since they all faced the same environmental stresses. With improved growing conditions the problem should diminish.

Sometimes gardeners pick zucchini from their gardens that are extremely bitter. If this happens to you do not try to eat the zucchini. A couple of grams of this extremely bitter squash can cause diarrhea and stomach cramps that can last for three days.

Since the flowers are insect pollinated it is possible in rare cases for a seed you receive in a seed packet to have been cross pollinated with wild cucurbits, resulting in high levels of cucurbitacins and a very bitter taste. When the cause of the bitterness is bred into the plant like this, the bitterness does not improve with better growing conditions.

Also, the bitterness is likely to be present in just one or a very few plants in the garden while most plants are normal. In the very unlikely event this happens to you, do not eat the squash from affected plants. Fruit from other plants that are not bitter should be fine.

(This resource was added August 2007 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement)

University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office

Contact Information

University of Nebraska-Lincoln
in Lancaster County
Web site:
444 Cherrycreek Road, Suite A,
Lincoln, NE 68528
| 402-441-7180