Why Are Your Cucumbers Bitter? Plus, 5 Growing Tips for Avoiding the Flavor

Bitter cucumbers are masters of disguise. They make look like the crisp, slightly sweet cukes you want to be eating, but once you take a bite, the bitterness is impossible to miss. Scientists have identified what makes cucumbers bitter and why that unpleasant flavor develops. Once you understand the causes, it's easy to prevent that bitter cucumber taste from ruining your next summer salad. These 5 easy-to-follow tips will help you avoid growing bitter cucumbers in your garden.

Why are my cucumbers bitter?

Many cucumbers are perfectly delicious while other fruit, sometimes even on the same vine, are bitter. The cause is an organic compounded call cucurbitacin. Bitter cucumbers contain high amounts of cucurbitacin in their fruit. All cucumber plants contain cucurbitacin but cukes grown in home gardens usually have very little of the harsh chemical in their fruit. It's mostly in their stems, leaves, and roots, where it can be helpful in deterring pests such as cucumber beetles.

Cucurbitacin migrates into the fruit during stressful growing conditions. Entering from the stem end of the fruit, the bitter compound might not spread through the whole cucumber, which explains why half a fruit—the stem end—is bitter and the rest of the fruit is perfectly tasty. Cucumber skin often contains more of the bitter compound than the flesh. Removing the skin helps to remove much of the bitter flavor as well.

How to Prevent Bitter Tasting Cucumbers

1. Choose the right varieties.

Some types of cucumbers are by nature more prone to bitterness than others. Plant breeders have selected new varieties based on the amount of cucurbitacin prevalent in the plant parts and stems. Plants with lower levels of cucurbitacin are less likely to become bitter in adverse growing conditions. Popular and easy-to-find non-bitter varieties include ‘Carmen,’ ‘County Fair,’ ‘Diva,’ ‘Green Knight,’ ‘Sweet Slice,’ Sweet Success,’ and ‘Tasty Green.’

High concentrations of cucurbitacin are sometimes accompanied by digestive discomfort. As a nod to preventing unsettling digestion, plant breeders have named some new varieties “burp-less.” Expect burp-less cultivars to be sweet, not bitter, and less likely to cause unpleasant digestive problems.

2. Provide plenty of water.

Cucumbers are more likely to become bitter during dry conditions. The cucurbitacin compound builds up in the plant as it struggles to grow. In time, the cucurbitacin makes its way to the fruit to create a bitter cucumber. When natural rainfall is scarce, water plants deeply to ensure they receive a total of 1.5 inches of water a week. Aim to water in the morning or late afternoon so foliage can dry quickly. Fungal diseases are more likely to develop on foliage that remains moist for long periods of time.

If you live in a dry region, consider installing a drip line or soaker hose near cucumber plants. Ultra-efficient and easy-to-use, these watering systems deliver a trickle of water to the base of a plant over a several hours. Pair them with a timer at the water source to make it even easier to provide the exact amount of water your cucumbers need.

3. Add mulch.

Spread a 2-inch-thick layer of shredded bark, straw, or grass clippings as a mulch around the base of plants to help conserve soil moisture and moderate soil temperature. Stressful growing conditions ranging from drought to heat to cold can cause bitter cucumbers. Mulch combats dry conditions by creating a barrier to limit soil moisture loss. A 2-inch layer of mulch also works to insulate the soil. The insulating power of mulch moderates temperature swings in the plant’s root zone which helps prevent non-bitter fruit.

4. Sow cucumbers every 2 weeks.

Succession sowing, the art of planting seeds every few weeks, is a great insurance policy for bitter cucumbers. Tough growing conditions, such as drought or excessive cold or heat, usually only last a week or two. By sowing cucumbers every two weeks beginning in late spring and continuing through midsummer, you’re likely to have many crops that ripen before or after whatever challenge Mother Nature throws your way. For example, if one sowing of vines is plagued by a heat spell and bitter fruit, the vines maturing a couple weeks later when the heat spell passes are likely to produce sweet, crisp cucumbers.

5. Be patient.

When dealing with bitter cucumbers, remember this too shall pass. Generally, as soon as the difficult growing conditions subside, newly formed cucumbers will have a pleasing taste and be a welcome addition to your next Greek salad, deli sandwich, or snack tray.