What to Do About Bitter Cucumbers

By on June 17, 2010

Cucumbers waiting for eating

I am one of those people who will not purchase out of season vegetables and fruits. Did you know that our food (if not grown locally) travels an average of 1500 miles, before reaching our tables? So my first cucumbers of the season are often from my own garden. After you’ve sown the seeds and nurtured the seedlings, dug in the cover crop, amended the soil with its annual meal of compost and nutritional goodies, watered, protected from bugs &disease and weeded…  It is truly a special moment when you finally begin to harvest your cucumbers.

The first cucumbers are usually very tasty, but sometimes, a month or so into cuke season, you’ll begin to harvest some that have a slightly bitter, to mouth-puckering taste. What’s really frustrating is you don’t know which ones will be bitter. You can’t safely offer your neighbors a bag without fear of embarrassment.  

How does that happen, and more importantly, what can you do about it? If you follow these tips to minimize a cucumber’s greatest enemy—stress—you’ll prevent bitterness.

Stress in a plant is most often caused by insufficient and uneven moisture, but temperature extremes and poor nutrition can also play a part.

To Avoid Cucumber Stress:

1. Keep them hydrated. Provide plants with plenty of moisture, especially around the time the plant is flowering and fruiting. Any water stress during this period of rapid growth causes the levels of bitter-tasting compounds to rise. Cucumbers are vigorous growers and therefore need between 1 and 2 inches of water per week, depending on the weather and the characteristics of your soil. The key is to keep the soil slightly moist at all times. Water deeply about once or twice a week—more often if you’re gardening in sandy soil.

2. Mulch. You can further reduce water stress by mulching plants with an organic mulch. Mulch helps to conserve and moderate moisture levels while blocking out weeds. Plastic mulches can be applied at planting time, but wait until the soil has warmed to above 70 degrees before applying organic mulches, such as straw.

3. Regulate the temperature. Cucumbers like warm conditions, but growing cool and tasty cukes in the heat can sometimes be a challenge. In fact, high temperatures not only affect fruit quality; they can also affect fruit set by causing the plant to produce a higher ratio of male flowers. “Cucumbers are really sensitive to high heat,” says horticulturist Emily Gatch, greenhouse and pathology coordinator with New Mexico-based Seeds of Change. “It can be really hard on plants if temperatures are consistently in the mid-90s.” If you’re growing cucumbers in a hot climate, Gatch recommends providing plants with filtered afternoon shade to help cool things down, either by strategically planting taller crops at the southern end of the bed or by adding a shade cloth to block 40 to 50 percent of the sunlight.

4. Give them sunlight and good soil. For the best-tasting fruit and optimum yields, grow plants in a sunny spot and in warm, fertile, and well-drained soil rich in organic matter. Raised beds are ideal. Cucumbers require a soil pH between 6.0 and 7.0. Wait to sow seeds or set out transplants until after all danger of frost has passed and the soil has warmed to at least 60°F. An unexpected frost will kill plants, and the vines grow slowly and become stressed in cool conditions. You can start seeds indoors three to four weeks before your anticipated planting date outdoors. Be careful not to disturb roots when transplanting.

5. Fertilize. Cucumbers thrive in light, friable soil. Several inches of organic matter worked into the soil prior to planting helps achieve that goal. Plants are heavy feeders, so be sure to feed the soil with rich compost or aged manure. After the vines develop runners and the first flowers appear, follow up with a side dressing of

compost, aged manure, or organic fertilizer. If the leaves are yellowish, the plants need more nitrogen. Make room. Giving plants the space they require is just one more ticket to a stress-free environment. Grow trellised plants 8 to 12 inches apart. Hills with one or two seedlings should be spaced about 3 feet apart, with rows 4 to 5 feet apart. Space bush varieties 3 feet apart in all directions.

6. Banish weeds. Keep your cucumber patch and the area around it free of weeds. Some types are hosts for bacterial wilt disease, which is spread by cucumber beetles. Intense feeding by these beetles can kill a plant, and they’re attracted to stressed plants—all the more reason to keep your plants healthy and happy.

7. Cover up. Row covers, hotcaps (or plastic milk cartons with the caps removed), and plastic tunnels are great for getting plants off to an early start. Row covers not only help plants grow faster and flower sooner, they also protect plants from pest insects. Just be sure to remove any covering once plants start to flower.

How to harvest

Some people harvest their cukes by turning the fruit parallel to the vine with a quick snap. Unless you’re skilled at making such a clean break, a pair of scissors or pruning shears might prove a better bet. Simply grasp the fruit and cut the stem 1/4 inch long.

For optimum taste and texture, American slicers are generally best when harvested at 6 to 8 inches long; Middle Eastern types such as ‘Amira’ at 4 to 6 inches; most picklers at 3 to 5 inches; and Asian varieties at 8 to 12 inches. 

What Makes a Cucumber Bitter?

Most cucumber plants contain compounds known as cucurbitacins (“kyew-ker-BIT-a-sins”) that cause fruit to taste bitter. At low levels, you aren’t likely to detect them. But high levels of cucurbitacins produce extremely bitter fruit. Some cucumber varieties possess a gene that inhibits their formation. “The bi gene causes the entire plant to be bitterfree,” notes Todd C. Wehner, Ph.D., professor of horticultural science and plant breeder at North Carolina State University. “Bitterfree plants always produce bitterfree fruit, even under stress conditions,” he adds. Although burpless varieties are bred to produce fewer cucurbitacins, they don’t have the gene that would make them bitterfree, so they could produce more cucurbitacins if growing conditions become unfavorable.

Bitterness concentrates in the stem end and skin and doesn’t penetrate the entire fruit. Cut off the stem end by about an inch or two. Rub the cut stub on the open end of the cuke.  This will produce a white foamy substance containing a large amount of the bitterness. If this has reduced the bitterness to an edible level, peel and eat. This process works best with cucumbers that are slightly stressed, but not very well on those that are ready for the psychiatrist couch.

Peaceful Valley sells several types of cucumber seed that possess the recessive bitterfree gene or are a burpless variety.  These include our Striped (Armenian), Lemon, Marketmore, Muncher, Suyo Long and most pickling varieties.

  Comments (8)


hi great post   2 thumbs up!  keep on the good work

Posted by Kent Ito on Jun. 21, 2010 at 9:46:39 AM


Thanks for your article it helped me in my research!

Posted by Izyc on Aug. 01, 2010 at 4:31:54 AM


It would be great if your cukes were labeled for greenhouse use when appropriate.  I tried to grow Armenian cukes in the GH last year only to find out later that there are male and female plants and not self pollinated.
Learning the hard way, one year at a time. A failed cucumber crop can’t be remedied until the following season.

What about the common English cucumber you see in the stores wrapped up in saran wrap? What variety is that?

Posted by Jean on Aug. 19, 2011 at 4:25:36 PM


Have enjoyed reading the posted info about picking cukes, but haven’t found an answer to a question I have concerning my cukes. 
Question 1:  My cukes grew very fast and large, with mostly a golden yellow color.  Are they okay to pickle?  This is my frist time to grow and pickle cukes.
Question 2:  Will cukes ripen more to green, if placed in a window, for sun exposure, similar to ripening tomatoes to red?

Appreciate any experienced growers information.  Thanks

Posted by MsMary on Jul. 12, 2013 at 6:21:58 PM

MsMary, For Question 1: Once the cukes turn yellow they are not good for pickling. They won’t be crisp enough to make a good pickle. Of course, lemon cucumbers are always yellow, but the others start green and then yellow as they age. For Question 2: No, don’t pick cukes and bring them indoors to ripen more. You want them crisp but not “ripe” and mushy.

Posted by GrowOrganic.com on Aug. 07, 2013 at 3:32:33 PM


Armenian cucumbers and other cucumber-melon varieties, such as the “Carosello Massafra” and “Carosello Polignano” are always bitter-free and burpless - and tend to grow very well in the heat.

As Jean mentioned, Armenian cucumbers are not able to produce fruit without pollination (parthenocarpic). They do grow very well in the heat and they are a great option for self-sufficient gardeners, though. This is because melon varieties do not suffer from the effects of inbreeding depression as much as regular cucumber varieties do. I have always struggled to grow enough regular cucumbers in a medium-sized garden to obtain decent seed, but I have always obtained high-quality seed from even a small patch of cucumber-melons.

Posted by Jay on May. 17, 2016 at 1:24:53 PM


I have many green cakes that are somewhat bitter.  Can I pickle them?  Wondering if the bitterness won’t be noticeable with the vinegar pickling sauce.

Posted by Deb on Jul. 26, 2016 at 2:08:11 PM


Deb, you can try cutting off the stem end (where much of the bitterness is concentrated) before you pickle them. I think the pickling brine will tone down the bitterness.

Posted by Suzanne on Jul. 27, 2016 at 11:15:51 AM

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