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How to avoid bitter cucumbers

Cucumber Seeds - F1 Burpless Tasty Green

If you’ve ever tasted a bitter cucumber, you’ll know how disappointing it is. Here we take a look at how and why cucumbers turn bitter and what you can do to avoid it happening. Whether you prefer to sow your own cucumber seeds or buy stress-free cucumber plants, here’s how to make sure your crisp, cool and juicy cukes remain free of acerbic undertones. 

Why do some cucumbers taste bitter?

All cucumbers have the potential to taste bitter. A member of the Cucurbit family along with squash and melons, cucumbers contain a bitter-tasting chemical called cucurbitacin. Normally, it’s confined to the leaves and stem of the plant, but sometimes, it migrates into the skin of the fruit, causing that foul taste when you bite into what looks like a succulent slice of home-grown fruit.

How to avoid bitter cucumbers

Cucumber 'Delistar' from Suttons
Sweet and aromatic, ‘F1 Delistar’ has a very thin, translucent and easily digestible skin
Image: Cucumber Seeds – F1 Delistar from Suttons

Cucumbers turn bitter for two main reasons – variety and stress. The first problem is confined to older varieties which produce male and female flowers. If you leave the male flowers in situ, bees and other pollinators extract pollen from them and fertilise the female flowers. You don’t want this, because these fruits will taste bitter. Remove any male flowers as soon as they appear. You can tell male from female by the absence of a bulge behind the flower head – the bulge is what turns into a cucumber and you’ll only find them on female flowers. 

If you like the older varieties of cucumber, that’s great, just remember that even one or two male flowers can turn the crop bitter, so be vigilant. Growing an all-female variety, like cucumber F1 Bella, helps to guard against this problem.

The other cause of bitter cucumbers is plant stress. Cucumbers need regular watering and you should aim to keep the soil moist but not waterlogged. Avoid over or under watering – little and often is best. Cucumbers love humidity, so make sure you mist and damp down your greenhouse, but do make sure there’s good air circulation or powdery mildew could turn your fruit bitter. Misting will also help to control spider mites which can cause plant stress and bitter fruit.

If you grow your cucumbers in a greenhouse, try to maintain an even temperature. Open the windows to avoid scorching your plants, but remember to close them again when the heat of the day is over. Use a quality compost that provides all the nutrients your cucumbers need, and remember that feeding is important for ensuring a tasty yield. While a standard tomato feed will do the trick, high nitrogen feeds are better for preventing bitterness. 

What to do with bitter cucumbers

Cucumber Plants ‘Merlin’ from Suttons
‘Merlin’ is an easy-to-grow all-female “midi type” that produces high yields
Image: Cucumber Plants ‘Merlin’ from Suttons

As soon as you taste your first cucumber, you’ll know whether you have a problem. If you’re unlucky and find that your precious harvest is tainted, there’s no need to throw it all on the compost heap. The good news is there’s a handy hack that will save the day. 

To cure cucumbers of bitterness, slice off both ends then rub the removed end against the exposed flesh and keep rubbing until a milky-white foam appears. Keep going until the foaming stops and then do the same at the other end. Give the cucumber a quick wash and enjoy. The bitter chemicals have been rubbed away!

If you’d like to know more about sowing and growing cucumbers, head over to our article, How to Grow Cucumbers, for all the information you need to produce a healthy crop.

Lead image: Cucumber Seeds – F1 Burpless Tasty Green from Suttons

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2 thoughts on “How to avoid bitter cucumbers”

  1. ralph says:

    I love this tip! No more throwing out bitter fruit-thank you!

  2. Jay says:

    Another possibility to growing a bitter-free cucumber is to grow out cucumber-melons such as Armenian cucumbers or Carosello. Though the light Armenian can be a bit bland and crunchy, many other varieties such as the Painted Serpent (striped Armenian) and the various Carosello do become bitter or cause indigestion. These are C. Melo (melons) so you can grow out your favorite cucumbers to seed next to them, and they will not cross.

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