5 Causes of Bitter Cucumbers and How to Fix Them
Cucumbers are best fresh. The last thing you expect when you bite into them is intense bitterness. This condition stems from a variety of factors, and it’s common during the summer. First discover what’s happening, then find out how to fix it.
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Every home gardener should try growing a cucumber vine. These plants are quick-growing and prolific producers. A single vine can grow dozens of cucumbers during the growing season.
Though they’re easy to grow, cucumbers occasionally experience issues during the growing season. Some grow bitter, and they cause burping when you eat them. They contain the natural compound cucurbitacin, which causes burping, bitterness, and indigestion.
This compound is naturally in the leaves and stems, though it moves into the cucumber fruits when the plants are under stress. This stress stems from environmental or preventable factors that affect the vines. Once you know what’s causing the bitterness, you can correct the issue in future cucumbers.
If a cucumber is already bitter, try cutting off its stem end and peeling its skin. Most of the cucurbitacin resides in those portions. If you cut them off and the cucumber is still bitter, discard it. It’s best to grow new ones that are less bitter, as there’s no fixing an already bitter cucumber.
Dry Weather
Droughts stress cucumber vines and cause them to grow bitter cucumbers. Without the moisture they need, the plants struggle to move nutrients throughout themselves. The cucumbers receive flushes of cucurbitacin that make them bitter.
The longer the drought is, the worse the bitterness will be. This commonly occurs in the middle of summer. Spring rains and cool temperatures dissipate, and high heat and lots of sunlight prevail.
The Solution
Fix dry cucumber plants by giving them plenty of water during the summer. Ensure their roots stay moist, but not soggy, while they grow in the garden. Set up automatic sprinklers, and verify that they’re watering the dirt sufficiently.
To test the soil, stick your finger into it. A simple finger test will tell you if enough water soaks into the soil. Pull your finger out—if it’s dry underneath, water. Wait to water if it’s wet.
Sometimes, sprinklers aren’t delivering enough water to the root zone. Modify the system, or back it up with some hand watering. Use a watering can or hose to add extra moisture during heat waves, and apply it directly to the root zone.
Adding mulch is another way to help. Thick mulch layers prevent water from evaporating, which keeps the ground soft, cool, and moist. Use compost, or find an alternative like straw, coco coir, or fallen leaves.
Temperature Extremes
Temperature extremes, both too hot and too cold, are not good for ripening cucumbers. The stress may cause the plants to push more bitterness into their fruits. Temperatures below 60°F (16°C) and above 90°F (32°C) are too cold and too hot.
More often than not, hot temperatures during summer are what cause the bitterness. This, coupled with dry soil, spells trouble for ripening cucumbers. Cold temperatures may be the culprit if the fruits are bitter at the end of summer and into fall.
There’s not much you can do about the weather, but you can take steps now to protect the plants from future extremes. A little prevention goes a long way.
The Solution
How to fix the issue depends on whether it’s too hot or too cold. When it’s hot, ensure the soil is sufficiently moist. Water it extra before heat waves, and again after the heat goes away.
Adding shade is beneficial during severe, hot weather. Use an umbrella, or put up shade cloth over the site. Yard shade cloths work well if you can’t find growers’ shade cloth like they use at plant nurseries.
When it’s too cold, use protective measures to warm the site. Row cover, or frost cloth, is a cheap material that works well. Simply drape it over the cucumber plants and weigh down its edges. The cloth traps heat, and it prevents ice and snow from harming the ripening cucumbers.
Poor Nutrition
Insufficient nutrients and poor soil may be causing the bitter cucumbers. Fix them by ensuring your plants have all the nutrients they need to grow well. Proper fertilization is key, as is consistent watering.
Without proper watering, the cucumber roots struggle to pull up nutrients from the soil. No amount of fertilizing will fix this, as the plants need water to move nutrients. Moist soil and proper fertilization are necessary for the roots to thrive.
Poor nutrition may also be the result of root disturbances. Burrowing pests can harm the roots, and excessive digging or cultivating can also damage the roots. Protect the root zone, and be careful when cultivating in the area.
The Solution
Your cucumbers may be experiencing a nutrient deficiency if you haven’t fed or fertilized them this year. The vines need lots of resources to grow well, and they’ll suffer when they lack vital nutrients.
I like to use compost for regular feeding. It insulates and protects the plants, and it feeds them with organic matter. When the weather is dry, it prevents water from evaporating and keeps the soil moist.
Add a two to three-inch thick layer of compost on the soil to feed your cucumbers. Well-fed plants won’t produce bitter fruits, so long as they have good weather and consistent moisture.
Potted specimens and those growing in raised beds may need more than compost to thrive. If the plants look tired and weak, and the cukes are bitter, consider adding a regular dose of an organic, well-balanced fertilizer. If you’re unsure, use a soil test to see how poor or fertile your dirt is.
Overgrown Cucumbers
As with squash, you don’t want to let cukes grow indefinitely. They’ll continue to grow and swell, and eventually they’ll turn yellow. Mature, overgrown cucumbers tend to be bitter, fibrous, and full of hard seeds.
Leave the cukes too long and you won’t see any more growth. This is because the vine believes it has produced seeds. After growing seeds, the annual plants begin to die back before the winter season. Constant harvesting prevents this from happening, and it encourages more cucumbers to grow.
The Solution
How big to harvest a cucumber depends on what you’re going to use it for. Pick snacking cukes when they’re small and fleshy. Pickle the pickling types, and snack on fresh-eating varieties.
Harvest larger cucumbers for slicing when they’re between six and ten inches long. Don’t let them get larger, as they’ll begin to harden their seeds and turn bitter.
Harvest cukes for pickling when they’re firm, juicy, and dark green. They should be between three and six inches long.
The Wrong Variety
Some cucumbers are bitter because of their genes! Certain types tend to grow more cucurbitacin than others. Many old hybrids and heirlooms are like this. You won’t realize until harvest time, when you find multiple bitter cucumbers on the same vine.
Growing multiple plants is one way to safeguard against this. It’s unlikely that every single seedling will have extra cucurbitacin.
The Solution
Rather than hoping your plants won’t have cucurbitacin, try growing burbless varieties. They’re cucumber cultivars that breeders created for their lack of cucurbitacin. They’ll grow delicious cukes without bitterness, and they’re more likely to fare well under high heat or dry weather.
Other new varieties have thin skin that stores less cucurbitacin than thick-skinned types. They’re also great for pickling, as their skin is easy to chew through.
