7 Causes of Cucumber Leaves Turning White[Complete Solution]

Cucumber is grown all around the world for its high nutrition values and easy maintenance. But as a grower when you see your cucumber leaves turning white, it means they need some care right away.

But the question; what types of care do they need? To know the answer, first, you have to know what are the reasons behind it

Powdery mildew, Transplant shock, Acidic soil, Sunburn, and Pest attacks are the main reasons for white vines of cucumber. 

And you will be happy to know. In this article, I will discuss all the reasons with the proper treatment.

So let’s get down to business-

Cucumber LeavesTurning White Fixing Guide

1. Powdery Mildew of Cucumber

Powdery mildew is one of the main culprits that turn the cucumber leaves white. Cucurbits like cucumber, squash, and melons are very prone to powdery mildew infection.

It’s a fungal disease that develops on both sides of the leaves and starts whitening first at the leaf edges. It seems like someone sprinkled talcum powder on the leaves. 

At first, it starts with small white spots but it covers the whole leaf area with white powdery substances. If untreated the whole cucumber vine can turn white.

How powdery mildew affects cucumbers?

Powdery mildew inhibits proper photosynthesis in the leaves. As a result, the growth of the plant gets slow. Even the fruit becomes smaller and of poorer quality. 

For the lack of photosynthesis, the leaves start to drop. Therefore making the vines vulnerable to sunburn.

Control Measure 

Cucumbers are very tender plants especially when they’re newly planted. So, pick a very good fungicide(our pick: Bonide Copper  Fungicide) and start applying according to the packaging label instructions as soon as you start to see the symptoms.

I’ve included some amazing homemade recipes below that is effective against powdery mildew:

#Recipe 1:- Milk Spray

Add milk and water in the same ratio. For example, Mix 200 ml of milk with 200 ml of water. Spray it twice a week until the problem stops.

#Recipe 2:-Neem Oil Spray

Mix 3 teaspoons of neem oil(our pick) in two liters of water. It’s very effective against any fungal and pest attacks. You can continue to apply it throughout your growing period. 

#Recipe 3:- Baking Soda Spray

Add two tablespoons of baking soda and 4 teaspoons of oil to one gallon of water. Spray once or twice a week.

#Recipe 4:- Cinnamon Spray

Take 3 teaspoons of cinnamon powder in 500 ml of water and mix well in a mixer. Let this solution rest overnight and then strain with a fine cloth and pour it into the sprayer. Spray on both sides of the leaves of the affected plant.

Preventive Measure

Powdery mildew can be hard to get rid of because it can overwinter in the soil and debris. And when it finds warm weather it comes out of its dormant state and starts infecting again.

So, Prevention is the best way to control powdery mildew on cucumbers. You can plant resistant varieties of cucumbers like ‘Brittania’, ‘Cobra’, ‘Excelsior’, ‘Eureka’ etc. 

Powdery mildew usually prefers a temperature around 22-32°C and humid weather for the infection. A good thing is, it cannot spread very much in sunny conditions. So, you have to plant your baby cucumbers in a sunny location with at least 5-6 hours of sunlight.

Secondly, Provide proper spacing (12 inches between each plant) to allow air circulation. You can also grow them in trellises or framed structures or vertical wires.

Water early in the morning so that the leaves have enough time to dry. Don’t wet the leaves.

Add organic mulch like dry leaves, straws, wood chips, etc to balance the soil moisture.

Avoid over-fertilization of Nitrogenous fertilizers. 

Disinfect any tools like shears or spades with bleach after working with diseased plants.

2. Cucumber’s Transplant Shock

Cucumbers don’t like their root system to be disturbed. Sometimes plants cannot withstand the change of transplanting and start showing some symptoms.

Transplant Shock can occur-

  • If the root is damaged during the transplant.
  • If there’s a lack of enough water in the new place.
  • If the location is different from the previous place.
  • If the soil is already harbored by fungus.

Control Measure 

You have to wait patiently and let the plant heal itself. Water the vines generously but make sure there’s good drainage. Mulch the ground with 2 inches of straw. You can also cut some leaves if it’s becoming too bushy.

Preventive Measure

Try not to damage the root while transplanting. Water them immediately after moving is finished. Lose some leaves so that the plant can focus more on growing the roots

Select the location where the soil is suitable. If possible sow seeds or seedlings in a suitable place where transplanting will not be necessary.

Sometimes powdery mildew fungus can be harboring already in the transplanted soil so before transplanting the seedlings make sure you are using fresh soil. 


Sunburns can happen when your plant is suddenly and very rapidly exposed to direct sunlight. This happens if you put plants directly in full sun from an indoor setting. 

The outer layers of the leaf tissue can burn easily if they are suddenly exposed to direct sun. And this leads the cucumber seedlings to turn white. If you are growing it indoors or in a greenhouse don’t move them into direct sunlight straight away.

If the sun exposure continues, leaves turn completely white as if they are bleached. It’s most likely to occur during the spring and summer.

Control Measure

Sadly there’s nothing much to do once the plants are already sunburnt. You can cut off the burnt leaves. Make sure you are feeding the plant enough water and organic fertilizers (our pick: Jobe’s Organics Vegetable Fertilizer)

Preventive Measure

Don’t expose the newly planted cucumbers to direct UV light from the greenhouse. Set the seedlings out for 2/3 hours on the first few days. Increase the exposure by an hour a day for the next 7 to 10 days. Avoid over-thinning of vines.

In the meantime lack of necessary sunlight can also affect photosynthesis and turn the leaves white. So make sure the cucumber plants get their required 6-7 hours of sunlight daily once they are established in the outer environment. 

4. Over-watering Of Cucumber

Too much of anything is never good. Likewise, Too much water on the ground creates a stressful situation for plants. The root cannot breathe comfortably in water-soaked conditions. 

The cucumber roots cannot uptake water and nutrients properly in waterlogged or soggy conditions. As a result, the plant makes less food for itself and loses its green foliage. It appears as yellow or white instead. 

Excess water also leaches out the nutrient faster so the plants become nutrient deficient and turn pale. You should regularly monitor watering. Correct the problem by feeding the plants with a fertilizer high in phosphorus.

You can test the soil with a moisture meter (our pick: Atree 3-in-1 Soil Tester Kits with Moisture, Light, and PH Test for Garden) Also, you can dip your finger in the soil to see if it’s moist.

Control Measure

Watering depends on vine size, soil conditions, and environmental conditions. You may not need watering if there’s frequent rain. You can do shallow watering if the soil seems dry.

Water only when necessary. Add organic mulch such as straw, bark chips, dry leaves, etc. These will help to keep the moisture in dry conditions.

5.Soil Acidity

In high acidity, plants cannot uptake nutrients efficiently so as a result, the leaves turn white. Cucumber prefers soil pH around 6-7.5.

Maintaining a favorable pH in the soil is extremely important for growing good quality cucumbers. 

But it’s better to check the pH level of the soil before coming to any conclusion. You can use a good pH test kit. Or you can still make an assumption about the soil acidity. 

Here’s the trick:

Mix half a cup of baking soda, half a cup of water into 2 tablespoons of soil sample. If there are bubbles the soil is acidic.

Control Measure

To lower the soil pH, add acid fertilizers and add lime fertilizer to increase soil pH. Here is our recommended lime and acidifier fertilizer-

  1. Jobe’s Organics Acidifier
  2. Jobe’s Organics Garden Lime

You can also add wood ash but there’s one small catch. Don’t let the seedling or roots come in direct contact with the wood ash. Because it can damage the seedlings.

6.Cold Weather Damage

Discoloration of leaves into white marks is one of the signs of cold damage. Cucumbers love warm weather between 18-23 C. So cold weather can freeze water in the plant cells. And this causes dehydration. As a result, water becomes unavailable to the damaged plant cells. 

Control Measure

Provide the vines with some protection from the cold. If a sudden cold is forecasted then cover the cucumbers with any light materials like bed sheets or plastic sheets at night. Remove them in the morning.

If you live in a colder region, place the plants in a heated greenhouse. The plants will heal in time. 

Do not apply fertilizer until they have recovered because fertilizers create new growth. Since the damaged plant cells are unable to produce enough food, supporting new growth creates even stressful situations for them. After the plant has recovered from cold damage prune the dead leaves. 

7.Pest Attack On Cucumber

Leafhoppers and Leaf miners can turn the foliage into white. Leafhoppers are very small insects. These pests pierce the leaves and suck on the leaf sap taking up the plant nutrients. And makes the leaves white and crispy.

Leaf miners tunnel through the leaf and suck the plant sap. While the leaf miners do not cause serious injury but cause pale and white blotches on the leaves. 

Control Measure

Since cucumbers are very tender plants, you need to pick the best insecticide for your cucumber plants(our pick: Monterey Garden Insecticide & Pesticide) that is equally safe and effective against pests.

Here’s some amazing home remedy that can clear off these pest problems:

#Recipe 1:-Horticultural Oil Recipe

  • Mix 1 tablespoon of liquid soap with 250 ml of any oil like soybean oil or vegetable oil or mustard oil. Keep this mixture as a stock solution in a bottle.
  • Then mix 4 teaspoons of this mixture with every 250 ml of water and pour it into the sprayer.

#Recipe 2:- Tomato Leaf Spray Recipe

  • Chop a cup of tomato leaves and let them stay overnight in 250 ml of water. 
  • Then strain out all the leaves and add another 250 ml of water to dilute the solution. 
  • Spray on the leaves twice a week. Tomato leaves have alkaloids that are toxic to insects but completely safe to plants and humans.


I have tried to provide all the necessary information about the cucumber leaves turning white with their treatment. and I hope you have got your solution.

Don’t panic because it’s easier than you think.

Maintain a good watering schedule, provide adequate sun, feed the right dose of fertilizers, and take necessary measures for fungal and pest problems.

Don’t forget to share your experience in the comments below about how you treat the white leaves and let me know if you have any queries.

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