5 Reasons Cucumber Leaves Turning Yellow and How to Fix It

Don’t worry if you saw yellow leaves on your cucumber plants. There are several reasons for this and ways to fix this common gardening problem.

There are five reasons why the leaves of cucumbers turn yellow:

  1. Not enough nutrients in the soil
  2. Cucumber plants that get sick
  3. Pests that can hurt cucumbers
  4. Watering problems
  5. Not enough sunlight

I’ll explain each reason why your cucumber leaves are turning yellow in more depth below. Once you figure out why your cucumber leaves are turning yellow, you can fix the problem and enjoy your beautiful homegrown cucumbers.

What’s Causing Cucumber Leaves Turning Yellow?


Making sure your soil has lots of nutrients to help your plants grow and do well is an important part of gardening. When you grow fruits and vegetables, this is very important.

I think the first thing you should do is test the soil. By taking a soil test, you can find out what your soil is missing so you can fix it. You can easily change the soil by adding fertilizer that is made for what you want to grow.

Nitrogen Deficiency

  • When there isn’t enough nitrogen in the soil, cucumber leaves often turn yellow. You need to fix this right away, or the cucumber plant could die.
  • Nitrogen is what makes plants grow and get leaves. It helps the leaves stay in good shape.

How can you give the cucumber plant more nitrogen?

  • Adding a couple of tablespoons of fertilizer to the soil of your cucumber plant is the best and easiest way to add nitrogen. You need a fertilizer with a 5:10:10 ratio. Make sure to use fertilizer according to the directions, as too much can hurt the plant and stop it from producing cucumbers.
  • You can add ammonium nitrate to the soil when the cucumber plant starts to flower. You only have to add a tablespoon. Do this again in three weeks.
  • You can also try covering your soil with a thin layer of compost.
  • If the yellow leaves are caused by a lack of nitrogen, these solutions should make them green again.

Potassium Deficiency

  • When cucumbers start to flower, they tend to need a lot more potassium.
  • Your cucumber plant might not have enough potassium if the edges and tips of its leaves start to turn yellow.
  • Use a fertilizer that has the right amount of each element.

Not enough iron

  • If your cucumber plant doesn’t have enough iron, the new leaves will be yellow, but the veins will be green.
  • You can fix this problem by spraying liquid iron on the leaves of the cucumber plant or by putting granular iron around the roots of the plant.
  • By taking a soil test, you can find out what your soil is missing so you can fix it.

Diseases of plants

Several diseases, such as cucumber mosaic virus, fusarium wilt, and downy mildew, are known to affect cucumber plants.

Cucumber Mosaic Virus

  • Cucumber mosaic virus is present if your cucumber plant has mild mosaic patterns, mottling, flecking, or leaves that look like ferns.
  • Aphids spread the cucumber mosaic virus, and it can infect a plant in the blink of an eye. In just a few hours, the virus can spread to a lot of plants.
  • The bad news is that you will have to take out the whole plant and any weeds that can carry the virus in order to get rid of the disease. The cucumber mosaic virus can live in the soil and hurt your plants again the following year. So, if this disease ends up being your problem, be careful about what you plant and where you plant it.

Fusarium Wilt

  • Fusarium oxysporum f. is the fungus that causes Fusarium wilt. sp. cucumerinum, which can live in the soil for a long time as long-lasting spores (chlamydospores) or with dead plant parts.
  • The fungus hurts the blood vessels.
  • If your cucumber plants are damping off, it could be a sign that they have fusarium wilt. Older plants may turn yellow, grow too short, and die. If your cucumber plant starts to wilt, it will likely die within 3–5 days.
  • Fusarium wilt can happen at any time during a cucumber plant’s growth cycle, and once it does, the plant must be thrown away.

Downy Mildew

  • Pseudoperonospora cubensis is a pathogen that causes Downy Mildew. It does well in wet or humid places.
  • Downy mildew can be seen when yellow spots appear on the surface of cucumber leaves and then turn the whole leaf brown. Angled leaf veins surround the leaf spots.
  • Downy mildew can’t live on dead plants, which is good news. It can only grow on plants that are still alive.

You should do the following to avoid and solve this problem:

  • Downy mildew is bad for cucumbers, so you should plant varieties that are resistant to it.
  • Plant your cucumbers far apart so they can get enough air and dry out.
  • If you see signs of disease, you should use fungicides. Fungicides will only work if you catch it early. So keep a close eye on your cucumber plants for signs of downy mildew.
  • Get rid of any plants that are sick.
  • What you need to know about powdery mildew White spots on cucumber leaves


Several different kinds of pests love to eat the cucumber plant.

  • Spider mites, whiteflies, and aphids all like to eat the juice in the leaves of cucumbers. When these bugs do this, the cucumber leaves can turn yellow.
  • You should get rid of these bugs right away because they can kill the plant.
  • You can get rid of these bugs by spraying insecticidal soap on the cucumber plant’s leaves.
  • The Potato Leafhopper is the most dangerous to cucumber plants, so keep an eye out for it.
  • Potato Leafhoppers also eat the juice in the cucumber plant’s leaves. But they inject the leaves with watery saliva, which hurts the leaves and makes them turn yellow. The plant’s leaves will fall off at some point.
  • To keep Potato Leafhoppers from doing damage, you can spray them with an insecticide, use row covers, and bring in bugs that eat potato leafhoppers, such as ladybugs, lacewings, and minute pirate bugs.

Water Problems

The way the plant is watered is another reason why cucumber leaves turn yellow. Changing how often you water can cause problems. Cucumbers need between 1 and 2 inches of water every week to grow well. Also, make sure the spot where you plant your cucumbers has good drainage. The best way to water cucumber plants is by drip.

Too Little Sunlight

  • The sun makes cucumbers happy.
  • So make sure they are planted in a spot where they will get at least 6 hours of sunlight a day. Some people do better when they get 8 hours of sun every day.


Should I get rid of the yellow leaves?

First, you need to figure out why the leaves are yellow. Once the cause is known, you can treat it. If a plant has a disease or is severely damaged, it may need to be taken out in its entirety.

Can you give a cucumber plant too much water?

Yes, you can give a cucumber plant too much water. Cucumber plants need about 1 to 2 inches of water every week. Also, they need soil that drains well.

What are some good plants to grow with cucumbers?

Peas, corn, beans, radishes, beets, carrots, and onions are all good plants to grow near cucumbers. Marigolds and sunflowers are also good companions as they repel beetles and insects that feed on cucumbers. People also think that oregano and dill can help keep bugs and other pests away.

What’s the deal with yellow leave cucumber plants?

cucumber leaves turning yellow reasons

Cucumber plants can turn yellow for a number of reasons, such as a lack of nutrients in the soil, diseases or pests that attack cucumber plants, problems with watering, or not enough sunlight. Which of the above solutions you use will depend on the problem you are trying to solve. If you know what to look out for and how to help your cucumber plants grow and do well, you will be able to help them grow and do well.