Sumo Gardener

Why Are My Cucumber Leaves Turning Yellow?

There are a number of reasons why the leaves on your cucumber plant are turning yellow. In this article, we’ll look at the reasons why this happens and how to prevent it in future. 

Cucumbers are one of the most abundant crops that you can grow at home. They’re tasty to eat, nutritious and perfect for the summer season.

Cucumbers are one of the fastest growing vegetables you can grow using hydroponics, enabling you to start harvesting cucumbers after just 55 to 75 days after planting the seeds!

How to Grow Cucumbers at Home

Cucumbers don’t require much maintenance as long as you keep the soil consistently moist. You should water your plants well each week so that the first inch of soil stays moist, and more often if the weather is especially hot or if you have very sandy soil.

Good moisture levels are important, as inconsistent watering can produce a cucumber that lacks flavor and has an irregular shape. The best way to keep your cucumbers properly watered is to use a soaker hose or irrigation that is on or just below the soil level.

This will not only keep them moist and growing vigorously, it also helps prevent diseases from attacking your cucumber plants.

Cucumber Leaves Turning Yellow

While they are easy to grow, these plants are prone to certain problems that will cause cucumber leaves to turn yellow.

When these problems start to become severe, the possibility of the cucumbers dying is high. Get to know what the causes of these yellow leaves and how you can prevent them below.

Why cucumber leaves turning yellow is a problem and how you can prevent invaders from affecting your plants.

Cucumber Leaves Turning Yellow Due to Nitrogen Deficiency

Cucumber Leaves Turning Yellow Due to Nitrogen Deficiency

One reason for cucumber leaves to turn yellow is a deficiency in nitrogen. In these cases, the leaves start to become pale, then they turn yellow and then the plant begins to die. 

The best way to treat this is to fertilize your plants with a 6-10-10 fertilizer, which is rich in nitrogen.

Once the flowers of the cucumber start to bloom, you can also add a tablespoon of ammonium nitrate to the soil and repeat this again after three weeks.

When adding nitrogen, always follow the instructions on your fertilizer and do not overdose your plants, as this will damage the plant roots and prevent it from producing cucumbers.

Diseases that Affect Cucumber Plants and Their Leaves

cucumber plants are prone to fungal and bacterial diseases, including mosaic virus and verticillium wilt.

Cucumber plants are prone to fungal and bacterial diseases, including mosaic virus and verticillium wilt.

Unfortunately, there are no known treatments for these diseases, and they will cause the cucumber plants to die. The best thing to do is to immediately remove all plants that are infested and destroy them to avoid the spread of the disease.

Once the area is cleared, avoid planting Cucurbitaceae family plants, including melons and squash in the same area where your infected cucumbers were.

This is because the diseases that affect cucumber plants can live in your soil and will infest the crop that you are going to plant next.

Pests that Affect Cucumber Plants

Pests that Affect Cucumber Plants

Parasites like spider mites, whiteflies, and aphids can also turn the leaves of your cucumber plants yellow. These pests feed on the sap in the leaves of the plant, causing them to yellow and die. 

Cucumber plants can resist and survive a small infestation, but if left untreated, this can quickly grow into a larger infestation that will kill the plant.

Fortunately, you can get rid of these pests by using an insecticide treatment. Start by treating all the leaves on your plant (not just the yellowing ones) on a weekly basis or as recommended by the manufacturer of your insecticide. 

Avoid using insecticide during midday or high temperatures, as this can burn the leaves.

Potato Leafhoppers are Feeding on Your Cucumber Leaves

Potato Leadhoppers feeding on cucumber leaves turning them yellow


Potato leafhoppers are one of the most dangerous pests for cucumber plants. Like aphids, they feed off the sap in the plant’s leaves, but their saliva contains a toxin that damages the plant and causes the leaves to turn yellow. 

Once the leaves get too damaged, they will drop off the cucumber vine. While a cucumber plant can resist a small infestation, a large infestation can kill the plant.

Rather than using an insecticide, it’s a good idea to develop good cultural practices around growing your crops. This includes encouraging beneficial insects such as ladybugs, lacewings and minute pirate bugs, as they feed off the potato leafhoppers and don’t damage your crops. 

Plant Companion Pants To Prevent Diseases and Pests

You can also plant companion plants with your cucumbers to support their healthy growth and make them more resistant to pests and disease. Good companion plants for cucumbers include peas, beans, radishes, carrots and onions.

Other recommended treatments include using dormant oil in winter to eliminate breeding adults, using insecticide at the very early stages of the infestation (it works more effectively on the young nymphs rather than the adults), and using floating row covers to create a physical exclusion barrier around your plants. 

Another good idea is to create a protective layer of mulch around your plants and, after the season is over, removing and throwing it away to get rid of any potato leafhopper eggs in the soil.

If you want to prevent yellow leaves on your cucumber plants and keep them healthy, follow the preventive measures mentioned above.

Why are you cucumber leaves turning yellow, how to prevent it

About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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