Why Are My Cucumbers Yellow? (Causes and Prevention)

Cucumbers are a popular vegetable to grow. They taste great and are good for you. Every once in a while, however, cucumbers have problems while growing.

This guide will explain why your cucumber is yellow and what to do about it. 

Why Are My Cucumbers Yellow?

Yellow cucumbers happen for five possible reasons.

  1. If cucumbers do not get enough nitrogen, the fruit may be yellow.
  2. If the cucumber gets too much sun, the chlorophyll gets damaged, and the fruit turns yellow.
  3. The belly of your cucumber may be yellow where it touches the cool, wet ground.
  4. Cucumbers that are overwatered can turn yellow.
  5. Finally, over-ripe cucumbers turn yellow.

What Do I Do With Yellow Cucumbers?

If your cucumbers are yellow because of a lack of nitrogen, you can eat them as usual. Sun damage makes the cucumbers tough and not good to eat. You can cut out the damaged part and eat the rest of the cucumber. Yellow belly cucumbers are edible but may not taste as good as cucumbers that are green all over. Cucumbers that are yellow from overwatering will not taste good and should be discarded. Overripe cucumbers are not edible. If the inside of your cucumbers is yellow, do not eat them. 

Round and Yellow Cucumbers

Lemon cucumbers are round and yellow when ready to eat. They resemble a lemon, hence the name. These cucumbers are supposed to be yellow and are good to eat. 

How Do I Fix Yellow Cucumbers?

You cannot fix yellow cucumbers. Once the cucumber is yellow, it will not turn green. In most cases, you should dispose of the yellow cucumbers. 

How Do I Prevent Yellow Cucumbers?

Since you cannot do anything to fix a cucumber once it is yellow, it is important to prevent them. For the most part, preventing yellow cucumbers means taking good care of your plants and fruit. 

Lack of Nitrogen

Cucumber vines need nitrogen, but too much nitrogen will make them keep growing and not produce blooms and fruit. In a study by the University of Delaware Extension, they found that using ammonium sulfate as one of the forms of nitrogen made cucumbers greener and less yellow. Instead of increasing the total nitrogen you give your cucumbers, make sure you use ammonium sulfate as your nitrogen source. 

Sunburn

Normally, the leaves of the cucumber plant cover the fruit and protect it from too much sun. If it is very hot and the leaves do not get enough water, they will wilt. In some cases, things like powdery mildew kill the leaves. Without the leaves to shade the fruit, they get sunburned. If your cucumber leaves are wilting, they need more water. If the leaves have fallen off the vine, you can use shade cloth to keep the cucumber fruit from getting sunburned. 

Over Ripe Cucumbers

Cucumbers turn yellow when fully ripe. The insides are fibrous and tough, making the seeds hard and inedible. Harvest your cucumbers when they are a good size but are still dark green. Letting the cucumber fruit turn yellow wastes the plant’s energy and lets the fruit go to waste. However, if you want to save the seeds of your cucumber plant, let one or two fruits get yellow and fully ripe. Remove the seeds, clean any fruit off them, and lay them out to dry. After the seeds are good and dry, place them in a glass jar or paper envelope and save them in a cool, dark place for next year. 

Yellow Belly

When a cucumber rests on cool, wet dirt, the part in contact with the dirt will turn yellow. Using a mulch around your cucumber plants can prevent the fruit from contacting cool, wet dirt and keep the cucumber from having a yellow belly.

Overwatering

If your cucumbers are yellow from overwatering, reduce the amount you water to one to two inches per week. While you can’t do anything about rain, you can make sure the soil drains well so any excess water soaks into the soil and away from the cucumber plant as soon as possible.

Other Cucumber Notes to Avoid Yellow Fruit

a female cucumber flower
a female cucumber flower

The best way to avoid yellow fruit is to take care of your cucumber plants and fruit. Here are some tips for doing that.

  • Plant your cucumber vines in pots or in the ground where they will get at least six hours of sun a day
  • Don’t plant your cucumbers around trees. The roots grow 36 to 48 inches deep, and if there are tree roots down there, the trees will starve the cucumber plants of water and nutrients. 
  • Till the earth to a depth of twelve inches and work three inches of compost into the soil. 
  • Do not use raw manure around your cucumber plants because it carries E. coli and other pathogens that can make you sick. 
  • Make ridges four to six inches high and thirty-six inches apart to plant your cucumbers on. The ridges make sure the soil will drain well. 
  • Pick slicing cucumbers for eating and harvest them when they are six to eight inches long and one inch in diameter. 
  • Pickling cucumbers should be harvested when they are three to four inches long and one inch in diameter. 
  • You can use young slicing cucumbers to make pickles, but they will not be as crunchy as pickling cucumbers. 
  • Buy only certified disease-free seeds. 
  • Don’t plant cucumbers until all danger of frost has passed and the soil begins to get warm. 
  • Plant three to four seeds one inch deep every twelve to fourteen inches on the ridges you made earlier. 
  • When the cucumber seeds germinate and have two true leaves, pinch off the weakest vines. Don’t pull them, as that will damage the roots of the seedling you leave in the ground. 
  • If you have a small garden, you can train your vines to grow on a trellis, up a wire, or on a welded wire cage to save space. Consult my article if you are looking for how far apart to plant cucumber plants.
  • You can plant fast-maturing crops like radishes and lettuce between the rows of cucumbers to use that space effectively. The radishes and lettuce will be ready to harvest before the cucumber vines grow too large. 
  • Scatter one cup of 10-10-10 for every ten feet of row when planting the cucumbers and work it into the soil. 
  • When cucumber vines are ten to twelve inches long, scatter one-half cup of 10-10-10 for every ten feet of row. 
  • Keep the soil evenly moist until the seedlings are about ten inches long. At that point, water an inch a week all at once. If the leaves wilt between waterings, water twice a week. 
  • Keep the rows of cucumber plants weed-free. Weeds steal water, nutrients, and sunlight from your vines. 
  • Do not hoe more than one inch deep around the cucumber vines to avoid cutting the feeder roots. 
  • Don’t be alarmed when the first flowers on the cucumber drop off. They are male. Female flowers with baby cucumbers at their base bloom next and do not drop off. 
  • If your female flowers are dropping off, take a male flower, carefully peel the petals off, and touch the protruding parts to your female flowers. Each male flower can pollinate five female flowers. 

In conclusion, cucumbers can turn yellow because of a nitrogen shortage, sunburn, touching cool, wet dirt, overwatering, or because they are over-ripe. Fertilize with a fertilizer that contains ammonium sulfate, shade cucumber fruits that are exposed to sunlight without leaves to shade them, use mulch around your cucumber vines, do not water too much, and pick the cucumbers while they are still green. 

Photo of author

Stephanie Suesan Smith

Stephanie Suesan Smith has a Ph.D. in psychology that she mainly uses to train her dog. She has been a freelance writer since 1991. She has been writing for the web since 2010. Dr. Smith has been a master gardener since 2001 and writes extensively on gardening. She has advanced training in vegetables and entomology but learned to garden from her father. You can see her writing samples at https://gardencopywriter.com/garden-writing, and her vegetable blog at https://stephaniesuesansmith.com/.

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