Bitter Fruit

Bite into a cucumber and, instead of crisp deliciousness, you get a bitter taste. What happened?!!?


Fruit can turn bitter for several different reasons. Unfortunately, once a plant produces bitter tasting fruit, you may as well cut it off at ground level and start again, because most of the fruit it will produce from then on will have the same taste. Also, the chemicals that cause the bitterness can make you sick. In extreme cases, they can even kill you. So, what makes fruit turn bitter and how can it be prevented?

Plants vulnerable to bitterness
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All members of the squash family can develop bitter fruit. This includes summer squashes, melons, pumpkins, and cucumbers. To a lesser degree, the cabbage family (broccoli and kale) and members of the rose family can also be affected.

​The rose family includes almonds, apricots, pears, plums, peaches, loquats, cherries, quinces, and strawberries, along with roses.

Melons, cucumbers, and more! (Kate Russell)

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Causes of bitter fruit

The bitterness is caused by chemicals, called cucurbitacins, that are always present in the roots, leaves, and stems of these plants. When the plant becomes overly stressed, it increases the production of cucurbitacins, which then make their way into the fruit. Scientists believe these chemicals are intended to discourage feeding by herbivores (and us). Common causes of stress that leads to bitter fruit include:

• extremely hot (or cold) temperatures
• overly dry weather
• sunburn damage
• irregular watering
• overwatering
• poor soil fertility

Steps to prevent bitter fruit

1. Select varieties that are less likely to become bitter in the first place. In the world of cucumbers, this means choosing ‘burpless’ and ‘bitter-free’ varieties.
2. Choose planting sites that provide stable temperatures. If your region regularly has temperatures that go above 90 degree F, provide your plants with afternoon shade.
3. Irrigate regularly, keeping the soil moist but not soggy.
4. Monitor soil health and fertility with a soil test from a reputable lab and make sure the soil pH is correct for the plants being grown.
5. Mulch around plants to stabilize temperatures, retain moisture, and eliminate weeds that will compete for water, nutrients, and sunlight.
6. Harvest fruit as soon as it is ready. The longer it stays attached to the plant, the more likely it is to become bitter.
7. Avoid prolonged storage and eat your produce while ii is fresh for the best flavor.

If your cucumbers have started turning bitter, you can still eat much of the fruit, simply by peeling it and tossing the stem end into the compost pile. If it still tastes bitter, compost it. The chemicals will disperse and break down.

Help your cucumbers, melons, and summer squash stay sweet with proper irrigation and a little sun protection.