Why Are My Cucumbers Bitter? Causes and Solutions

Cucumbers are known for being prolific plants, but sometimes the fruits emerge bitter. This is generally caused by either stress on the plant or the variety of cucumber, which means it's easy to prevent in your own garden. Learn why cucumbers taste bitter and how to fix it in your own garden.

Why Do My Cucumbers Taste Bitter?

Cucumbers taste bitter because of cucurbitacin, which is a compound that is always present in cucumbers, but the levels change based on the cucumber growing process. With cultivated cucumbers, which all contain cucurbitacin B and cucurbitacin C, the compounds are supposed to make their leaves bitter and less tasty to munching animals.

These compounds are usually confined to the leaves and stems of the plants, parts of the plant humans don't eat, so we are not aware they are there. Unfortunately, due to stressors from the climate and extreme temperature changes, soil, over-watering or under-watering these compounds can move from the leaves to the fruit. That results in a bitter taste.

Additionally, when pollinators extract pollen from the smaller male flowers and pollinate the female flowers, this also causes a bitter taste.

However, it is not the whole fruit that turns bitter. More commonly, the bitterness will be concentrated at the stem end and the area right under the skin.=

How to Prevent Bitter Cucumbers

While you can't fix bitter cucumbers, you can take a few preventative steps while growing cucumbers to avoid the following growing conditions that are potential culprits of bitterness.

1. Keep Cucumbers Well Watered: Long periods of hot, dry weather can contribute to bitter cucumbers. Keep your cucumbers well watered by giving them a deep soaking of at least an inch of water per week, more during extreme dry spells. Consider adding drip irrigation to ensure the plants receive adequate, consistent moisture, add mulch to the area around the roots, or install a shade cloth to provide filtered light to the plants during the hottest part of the growing season.
2. Enrich the Soil: Lean soil and a general lack of nutrients can cause bitter cucumbers, so a soil rich in organic matter will go a long way toward producing less stressed, better tasting cucumbers. Add compost when preparing beds, and then side-dress the plants throughout the growing season. If your soil is less than ideal, give your cucumbers balanced fertilizer every 4 to 6 weeks.
3. Remove the Competition: As heavy feeders, cucumbers dislike competition for water and nutrients, whether it's from other cucumber plants or weeds. Keep the bed weed-free, and space the cucumber plants appropriately when sowing seeds in the spring. Plant trellised or caged cucumbers 8-12 inches apart, and increase the distance for mounded plants to 3 feet apart.
4. Plant in a Sunny Spot: Overcast areas, like the Pacific Northwest, have reported bitter cucumbers due to lack of sun. You can't control the hours the sun will shine, but you can plant in a spot that gets full sun as nature will allow. If it's cool and damp, as well as overcast, growing your cucumbers undercover, like a polytunnel, will amplify the available heat and light. Avoid planting cucumbers in areas that will be shaded by taller crops.
5. Choose the Right Variety: Select a variety of cucumber that only produces female flowers, like Gynoecious varieties. This way, you avoid the pollination that can cause bitter cucumbers.

So even though cucumber plants grow rather easily, and you can get a prodigious harvest from a couple of plants, to get quality as well as quantity, you need to provide them with good growing conditions: plenty of sunshine, regular water, and rich soil.

As with all plants, edible or otherwise, the real trick to healthy, productive cucumber plants is to research what growing conditions the plant prefers and do your best to provide them. Even a few days of stress can cause a ripple effect of damage.

Ornamental plants will probably recover, but you only get one chance to get it right with cucumbers and other edible plants. That's why it is so important to put some thought into choosing both your growing site and your edible varieties.

Non-Bitter Cucumber Varieties

Look for varieties that are well-suited to your area and that are labeled "non-bitter." Some reliable varieties are 'Marketmore 97', 'Diva', 'Eversweet,' 'Long Green Improved', and the heirloom 'Lemon.'

Another tip is to look for any variety with "sweet" in the name.

What to Do With Bitter Cucumbers

If you find yourself with bitter cucumbers, don't automatically reach for the compost bucket. You can rub the ends to help with bitterness. Simply cut the ends off, rub the end's skin on the inside of the cucumber until foam comes out, then rinse off the foam, which is the bitter part.

Peeling the fruit should also improve the flavor. Cut off the first inch or two from the stem end and test the flavor. If it's still bitter, try a slice toward the center of the cucumber and see if it is sweeter. You should be able to salvage more than enough for a salad.