5 Reasons for Cucumber Leaves Turning Yellow [360 Degree Solution]

Cucumbers are refreshing summer vegetables. It is very popular among the growers for its easy and fast-growing nature. But suddenly noticed that your cucumber leaves are turning yellow.

And you want to know why are the cucumber leaves turning yellow and how you can revive the plant?

Watering Problems, Lack of sunlight, Nutrient deficiency, Pest attack, and some Diseases are the reasons for the yellow leaves of your cucumber.

And Good news; the yellow leaves problem can be solved easily. And in this article, I’ve discussed the causes with practical and effective solutions.

How To Fix Yellowing Cucumber Leaves Fast?

1.Watering Problem of Cucumber

The most common reason for cucumber leaves turning yellow is the watering problem. If you overwater the cucumbers, the leaves will start to turn yellow and fall off.

Again underwatering the cucumbers can do the same thing. Underwriting also turns the leaves yellow on the edges and later they can turn brown. This can even lead to dying off of the leaves. 

You can use a moisture meter to check the moisture to be more precise (our pick: Atree 3-in-1 Soil Tester Kits with Moisture, Light, and PH Test for Garden). Or you can also dip your finger up to the first knuckle into the soil. For the cucumbers, the soil should be moist, not waterlogged.

Control Measure

Check the soil first. If the soil is dry then watering regularly for a few days will fix the yellow leaves. But if the soil is too wet then provide better drainage at once. You can add sand or perlite to increase drainage (our pick: Miracle-Gro Perlite).

If you are growing cucumbers in containers then keep large drainage holes.

Preventive Measure

Cucumber plants need 1-2 inches of water every week. But the watering schedule depends a lot on weather conditions. If there’s heavy rain you can skip watering for a few days. If it’s too hot outside then you can increase the watering a bit.

Use Organic matter like peat moss, vermiculite, sawdust, rotted manure, etc with the soil to improve drainage.

Water them during the morning at ground level. To prevent fungal growth avoid wetting the leaves.

2.Nutrient Deficiency Of Cucumber

Cucumbers are heavy feeders. So nutrient deficiency can be a common problem. Almost all kinds of nutrient deficiency turn the leaves yellow.  Having balanced nutrients is very important for good cucumber production.

Lack of Nitrogen, Iron, Magnesium, and Potassium can make the cucumber leaves yellow with green veins. It’s called interveinal chlorosis. But the good thing is that this can be fixed easily.

Nitrogen deficiency turns the old leaves yellow while newer leaves continue to look green.

Magnesium and Potassium deficiency turns the leaves yellow around the edges and produces small leaves. Iron deficiency makes the younger leaves yellow first while the older leaves continue to stay green.

However, it’s not possible to detect the exact deficiency problem just by seeing the leaves.

Usually, A soil test is required to determine the exact nutrient deficiency in the soil. But a pH test can also give a good idea of the deficiency.

For example, if the pH level is higher than 7, it can be iron deficiency while calcium deficiency can occur when the pH level is too low. You can get this pH test kit.

Control Measure

Cucumbers require more Nitrogen and potassium than other plants. Apply well-balanced vegetable fertilizer to the cucumber (our pick: Jobe’s Organics 9026 Fertilizer).

For Magnesium deficiency, you can use Epsom salt(our pick: Epsoak Epsom Salt)Add half a tablespoon of Epsom salt in 2 liters of water and apply it to the soil

Apply chelated iron for iron deficiency (our pick: Southern Ag 01952 Chelated Liquid Iron)

Always apply fertilizers according to the instructions of the package label so that you don’t injure the cucumbers with an overdose.

3.Lack of Sunlight

Cucumbers are sun-loving plants. They need at least 6- 8 hours of sun every day. If they aren’t getting proper sunlight, the leaves will start turning yellow. 

Control Measure

Place your cucumbers in a sunny location where they get at least 6 hours of direct sunlight.

And if you are growing under artificial lights, keep the lights on for 12-16 hours because grow lights are less effective than the sun. 

4.Pest Attack on Cucumber

Aphids, Spider Mites, Leafhoppers, and White Flies feed on the leaves of the plant and make them yellow.

Leafhoppers are very harmful because they release a toxin into the leaves. It also causes brown spots on the yellow leaves.

Small infestation isn’t very harmful but a large infestation can kill the plant. Keep an eye on the lower surface of the leaves. Look out for movements in the plant. 

Control Measure

Cucumbers are very tender vegetables. So you need to choose the best organic insecticide for cucumber (our pick: Monterey LG6150 Garden Insect Spray). Also, you can go with Neem oil or insecticidal soap. (our pick: Natria Insecticidal Soap).

Here are some effective home remedies that can control these pest problems-

#Recipe1:-Insecticidal Soap Recipe

Vegetable oil mixed with mild liquid soap can be very effective against pests. Mix one cup of oil and three teaspoons of liquid soap. You can store this oil mixture in a bottle. 

Add two teaspoons of this mixture in one liter of water and spray directly into the leaves. This mixture will suffocate and eventually kill the insects.

#Recipe 2:- All-In-One Insect Spray Recipe

  1. Take one bulb of garlic and a small onion and make a paste of them in an electric blender.
  2. Add a spoonful of dry pepper powder to the paste. Then let it sit for a few hours
  3. Strain the mixture and add 3 teaspoons of liquid soap and mix very well
  4. Now make it a 2-liter solution by adding water.
  5. Spray it on both sides of the leaves for better results
  6. Be careful while handling the mixture as it contains hot pepper. 

#Recipe 3:- Neem Oil Recipe

Neem oil comes in very handy against insect and fungal attacks.

  1. Mix half a tablespoon of neem oil in a liter of water. 
  2. Then pour it into the sprayer and spray it twice a week.

#Recipe 4:- Orange Spray Recipe

  1. Boil 2 cups of water and remove it from heat.
  2. Peel an orange and add these peels into the hot water.
  3. Cover with a lid and let it stay until the water cools down.
  4. Remove the peels and spray them on your leaves.

Preventive Measure

Avoid excess fertilization of any nutrient. Don’t let the soil dry because spider mites prefer dry conditions better.

Avoid using insecticide during high temperatures. This can burn the leaves.

Encourage beneficial insects such as ladybugs, lacewings. Because they feed off these harmful insects and don’t damage the plants.

5.Diseases of Cucumber

Some fungal problems and the Cucumber mosaic virus results in the yellowing of leaves. Fungal problems include Root rot, Stem rot, Fungal Wilt, and downy mildew.

Overwatering can lead to root rot and stem rot that makes leaves turn yellow and then brown. Fungal wilts turn the bottom leaves yellow and cause the death of the plant.

Downy mildew causes large, yellow, angular spots on the upper side of the cucumber leaves. Severe infestation turns the leaves yellow and later brown.

Cucumber mosaic virus is another disease that creates yellow spots on the cucumber leaves. It’s a very deadly virus as it kills the plant.

Control Measure

It is best to remove the diseased plants to stop spreading any further. Get rid of the mosaic-infected plants as soon as possible. The cucumber beetle is responsible for fungal diseases so keep an eye for it and apply a safe insecticide.

Apply a good and non-toxic fungicide for any kind of fungal infection. You can try this (our pick: Bonide Copper  Fungicide)

Here are some very effective home remedies you can give a try for the fungal problems:

#Recipe 1:- Baking Soda Mixture

Items required-

  1. 2 teaspoons baking soda
  2. 1 teaspoon of liquid soap
  3. 1 teaspoon of any cooking oil 
  4. 2 liters of water


Combine all these and spray them on the infected plant

# Recipe 2:- Copper Spray Recipe

Copper spray is very effective against any fungal attacks.

Items required-

  1. 5 teaspoons of copper sulfate
  2. 75 ml of Hydrated lime 
  3. 2 liters of water.


  1. Mix this solution very well every time before spraying.
  2. Wash the sprayer thoroughly after every use because this solution is very corrosive.

# Recipe 3:- Epsom Salt Spray Recipe

  1. Add 3 teaspoons of Epsom salt in 2 liters of water 
  2. You can spray this solution every week until the fungal problem solves

Preventive Measure

Avoid over-watering and overfertilization. Keep proper plant spacing and Avoid using the same place to grow cucumbers where vegetables such as peppers, tomatoes, and squashes have been grown.


Cucumber needs more water or fertilizer. In addition to these steps, you can also try giving them a deep mulch of compost and organic matter as this will help with their nutrient uptake. You should see improvement within one week if your plants are not diseased.

I hope this article helped you fix the yellow leaves of your cucumber.

I have tried to provide all the necessary information and solutions about the yellow leaves. You can also apply the same actions mentioned above for your Tomato and Squash plants.

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