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Why Are My Cucumbers Bitter? Are They Safe to Eat?

Now that summer is here, home vegetable gardeners are just starting to enjoy the fruits of their labor. A common question that I get from readers is “why are my cucumbers bitter?” Many also want to know if bitter garden cucumbers are safe to eat.

Bitter cucumbers can stem from a combination of factors, particularly the levels of cucurbitacin in the variety you have chosen to grow, but also because of environmental conditions, genetics, the timing of your harvest, and more.

Keep reading to find out how you can minimize the chances of growing bitter cucumbers and what to do if you do encounter them.

Cucumbers and sunflower with a white card that reads bitterness in cucumbers, what causes this, what to do about it and varieties to grow.

Are bitter cucumbers safe to eat?

Have you ever picked a cucumber, expecting a delicious, sweet flavor only to discover that it is extremely bitter? Are these cucumbers safe to eat?

Bitter cucumbers can be safe to eat, but it is generally recommended to avoid consuming them since the bitterness can be caused by high levels of cucurbitacin. 

Although most cultivated cucumber varieties have been bred to have low levels of this compound, some bitterness may occasionally be present due to genetic variation or environmental factors.

In cases like this, the bitterness is usually mild and not harmful if consumed in moderation.

To ensure safety, though, it is recommended to select cucumbers that are known for their low bitterness, such as those commonly found in grocery stores and those grown for their low cucurbitacin level.

What is cucurbitacin?

Cucurbitacins are compounds produced by the plants as a natural defense against herbivores and other pests. The bitter taste that the compound produces discourages the animals from consuming them.

Skeletal formula of the compound cucurbitacin which makes cucumbers bitter.

Unfortunately, this bitterness can also make them unpleasant to humans.

The compound cucurbitacin tends to be produced in highest amounts when the plant is under stress from lack of water, or excessive heat. It is found in the leaves, stems and roots of the cucumbers.

Cucurbitacins have also gained attention in research and medicine due to their potential health benefits. Some bitter cucumber benefits are that they are thought to have anti-cancer, anti-inflammatory and anti-microbial properties.

It is worth mentioning that cucurbitacins can be toxic if consumed in high amounts. For this reason, it is important to consume cucumbers that are bred for low cucurbitacin content or those that are fully ripe and properly prepared.

Reasons for bitterness in cucumbers

The main reason for bitterness in cucumbers is cucurbitacin – a natural compound that the cucumber produces. Other plants in the cucurbitaceae family – also known as the cucurbit family –  (melons, pumpkins and gourds) also produce the same compound and it makes their fruit bitter, too.

High levels of cucurbitacin in your cucumber variety will result in bitterness. This level can vary among different cucumber varieties and even within the same plant.

Cucumber breeders have worked to develop cultivars with low cucurbitacin levels to minimize this bitterness. It is important to choose cucumber varieties known for their mild or sweet flavor as an effective way to avoid bitter cucumbers.

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Four cucumbers labeled in a collage with words non-bitter-cucumbers.

Some no bitter cucumber varieties and types are:

  1. Sweet Success – A burpless English cucumber with a very sweet flavor.
  2. Sweet Slice – They are sweet, not bitter, and burpless (won’t make you burp) with thin skin that requires no peeling.
  3. County Fair – A pickling type of cucumber that has it all –  strong production, good disease resistance, and excellent quality burpless fruit.
  4. Tasty Jade F1 – One of the best Asian cucumbers on the market. They are crisp and do not taste bitter.
  5. Diva – a 2002 All-America Selections Winner! This variety produces high yields of non-bitter burpless and seedless cucumbers. 
  6. English Cucumbers –  They are also known as hothouse or seedless cucumbers, and are typically less bitter compared to other cucumber varieties. They have a mild, sweet flavor.
  7. Persian Cucumbers – These small, thin-skinned cucumbers have a crisp texture and mild flavor. They are often described as being sweet and almost seedless.
  8. Japanese Cucumbers –  These cucumbers are slender and have a dark green, thin skin. They are known for their crisp texture, mild flavor, and low seed count.
  9. Armenian Cucumbers –  These also called snake cucumbers, and are long and slender with a pale green skin. They have a mild, slightly sweet taste and a crunchy texture.

Remember that there are some cucumber varieties that naturally have a slightly bitter taste. For example, some heirloom or wild cucumber varieties may have a bitterness to them. 

However, if you are consistently growing cucumbers that are bitter when they are supposed to be sweet, the reason is likely the amount of cucurbitacin in the fruit.

Environmental factors can cause bitter cucumbers

Environmental conditions play a role in the bitterness of cucumbers. Heat, water and nutrients can play a role in causing bitter cucumbers.

High heat and lack or water

If you have very high temperatures, particularly during the fruit development stage, this can trigger the production of cucurbitacin.

Cucumber plant with yellow watering can in a dry hot garden bed.

If this heat continues for a long time, the stress to the plant may push it to develop even more bitterness. A lack of water and nutrient deficiencies can also stress the plants, leading to an increase in cucurbitacin levels.

To prevent bitterness because of these environmental factors, it is important to provide the best growing conditions for cucumber plants. This includes making sure the plants get enough water, making sure the soil maintains moisture, and keeping a consistent temperature range.

Give cucumbers a deep soaking when you water so that they receive at least an inch of water per week, and even more during long dry spells. Drip irrigation is beneficial if you wish to ensure that the plants receive adequate moisture.

Providing shade during hot periods by using row covers or shade cloth will help, as will the use of organic mulch to regulate soil moisture.

Succession planting – planting cucumber seeds every few weeks instead of all at once, helps to keep your cucumbers bitter-free. Drought, and excessive heat or cold conditions generally only last a few weeks.

By sowing seeds over the course of several weeks, you can escape some of these tough conditions.

Garden soil with blocks reading compost.

Lack of nutrients

Cucumbers are rich feeders. When planting, be sure to add compost or other organic matter to your soil to make it fertile.

This rich soil will go a long way towards the production of great tasting cucumbers. Be sure to side dress during the growing season or add a balanced fertilizer.

Crop rotation can be a big help in enriching your soil which will, in turn, help prevent bitterness in cucumbers.

Cucumbers grown in mounds or raised beds will allow the soil to warm early in the season and avoid the stress brought on by soil that is too cool.

Be sure to also keep the beds weed-free so that the cucumber plants will get all of the nutrients from the soil.

Bitter cucumbers because of genetics or seed quality

The genetics of cucumber plants play a significant role in determining how bitter the fruit will taste. Some heirloom or wild cucumber varieties are known for their higher cucurbitacin content, resulting in a more pronounced bitter taste.

When you select cucumber seeds, choose varieties that are labeled bitter-free, burpless, mild and sweet.

Cucumber seeds spilling out of a package.

The age of your seeds can also make your cucumbers bitter. Older seeds may have higher cucurbitacin levels, leading to a greater chance of bitterness in the plants.

It is recommended to use fresh, high-quality seeds obtained from reputable sources to reduce the likelihood of getting bitter cucumbers.

The timing of your harvest could make your cucumbers bitter

If you wait too long to harvest your cucumbers, you can end up with bitter fruits. Overripe or mature cucumbers tend to be more bitter.

Over-ripe cucumber with wilted brown leaves.

As cucumbers reach their full maturity, they will naturally produce more cucurbitacin. Because of this, it is necessary to harvest cucumbers and other cucurbitaceaes at the correct time to ensure a milder flavor.

Ideally, the cucumbers should be firm, evenly colored, and free from yellowing or other signs of over-ripeness.

Other factors causing bitter cucumbers

Bitterness in cucumbers can sometimes happen because of the way you handle or serve them. Leaving the skin on the cucumber can be a factor, since the skin tends to contain higher concentrations of cucurbitacin. 

Also, the ends of the cucumber tend to have higher levels of cucurbitacin, which can make a difference in their taste. Scooping out the seeds can also help, as they can contribute to bitterness, too.

Before using cucumbers in recipes or serving them, it is a good idea to taste a small piece to ensure they meet your sweetness expectations. This way, you can avoid using overly bitter cucumbers in dishes.

How to fix bitter cucumbers

In spite of following the tips above, you may still discover a sour tasting cucumber. This may have you wondering how to fix bitter cucumbers.

If you do end up with cucumbers that aren’t as sweet as you would like, don’t just throw them on the compost pile. There are a few things you can do to reduce the bitterness.

Man in a blue shirt peeling a cucumber.

Soak cucumbers in salted water. Adding vinegar or lemon over cucumber slices will also help. Peeling the cucumbers and cutting off the ends helps to remove the bitter taste.

Salted water will help to draw out some of the bitter compounds. The acidic properties of vinegar or lemon juice can help to counteract the bitterness.

Blending or cooking bitter cucumbers can help to reduce the sour taste since the bitter flavor can be masked by adding other ingredients, such as in a soup or stir-fry.

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Cucumbers on a cutting board with words What Causes Bitter Cucumbers?

Yield: 1 printable

Printable - Variety of Bitter-Free-Cucumbers

Printable - Variety of Bitter-Free-Cucumbers

Nothing is worse than biting into a fresh garden cucumber, expecting a sweet taste, only to discover that it is bitter.

These varieties and types of cucumbers have been bred to be bitter-free.

Print out the printable and add it to your garden journal.

Prep Time 5 minutes
Active Time 5 minutes
Total Time 10 minutes
Difficulty easy
Estimated Cost $1


  • Heavy card stock or glossy photo paper


  • Computer printer


  1. Load the heavy card stock or glossy photo paper into your computer printer.
  2. Choose portrait layout and if possible "fit to page" in your settings.
  3. Print the calendar and add to your gardening journal.


A printable showing types and varieties of bitter-free cucumbers.

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Monday 28th of August 2023

Thank you, I found your article very informative

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