cucumber leaves turning white

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One of the most common questions gardeners ask when growing cucumbers is “Why are my cucumber leaves turning white?”

Cucumber leaves turning white can be a real problem for cucumber plants. In this post, we will try to find the actual reason for the whitening of cucumber leaves.

If you are looking for cucumber growing tips in general see our earlier post here.

Why There Are White Spots After Transplanting My Cucumber Seedlings:

Cucumber leaves that are turning white after transplanting are suffering from transplant shock. Plants go through a period of stress when they are replaced from one location to another, due to a lack of water and nutrients, as well as changes in temperature or other environmental conditions.

Why My Cucumber Leaves Turning White at the Edges

There are many reasons why cucumber leaves can turn white. It can be due to some disease, pest infestation, excess moisture, accidental blanching, or simply maturity.

Let’s dig deep into these possible reasons:

1. Diseases

One of the main causes of whitening your cucumber leaves is a disease called powdery mildew.

The Powdery Mildew Disease:

Powdery mildew is the white coating that can cover the entire surface of your cucumber plant, including leaves, stems, and even fruit. This fungal disease is caused by a lack of air circulation in the plant’s environment or a lack of sunlight. It often begins on older leaves and spreads to younger leaves.

This disease is common in cucumbers, as well as zucchini, pumpkins, and other members of the Cucurbitaceae family.

The disease looks like a white or gray powdery substance on the cucumber plant’s leaves and stems. It usually begins on lower leaves and spreads up the plant.

In severe cases, it can cover most of the leaf surface. The spots appear as grayish-white patches, which enlarge and merge together to form large colonies.

If left untreated, it can cause stunted growth and twisted, distorted leaves. Eventually, the plant will die.

Powdery mildew is difficult to get rid of and you have to take all the precautionary measures necessary not to allow it in your garden.

The spores are carried in the wind and can infect plants quickly if conditions are right. It’s easy to see why this disease is so hard to fight, as it often attacks under the leaves and isn’t noticed until it’s too late.

How to Fight Powdery Mildew Disease:

The white spots produce on the top of leaves are not harmful to the plant but it does reduce the plant’s ability to photosynthesize.

This means that your plant will be getting less sunlight which can prevent proper growth. While this disease doesn’t usually kill plants, it can make them more susceptible to other diseases and even death if left untreated.

The best way to control powdery mildew is through prevention and early detection.

The first step is to make sure your cucumber plants are getting enough sunlight, at least 6 hours per day.

Remove any dead plants and debris from your cucumber patch to reduce the spread of spores.

To prevent powdery mildew on cucumber plants, you need to create a homemade fungicide. Mix together 1 tablespoon baking soda and 1 gallon of water with a squirt of dishwashing liquid.

Use distilled water if your tap water is high in chlorine or minerals, which can harm your plants. Shake the mixture well to evenly distribute the baking soda into the water.

Spray your cucumber leaves with this mixture weekly during warm weather — when temperatures are above 75 degrees Fahrenheit.

Spray both sides of your plant’s leaves thoroughly but avoid getting any solution on the fruit itself, as this may cause it to rot prematurely.

You can also spray the cucumber plants with a solution of 1 tablespoon of baking soda to 1 gallon of water.

Vinegar also works great on fungi. Add 3 tablespoons of vinegar to 1 gallon of water and spray on the leaves. Don’t add too much vinegar to the solution or it will burn the leaves.

2. Pests:

A pest infestation can also be a probable cost for the whitening of cucumber leaves. One such pest is the leafhopper.

Leafhopper (Empoasca spp.):

Leafhoppers can be distinguished from other insects by their wedge-shaped body, small size, and their habit of jumping when disturbed. They suck plant juices from leaves and stems. Leaves turn yellow and curl upward.

There are many organic pest control techniques that you can use to protect your cucumber plant.

A spray made from garlic extract and water might help in severe infestations.

3. Excess Moisture:

Cucumbers like moist but well-drained soil. If the soil is wet all the time, the roots of the plant can’t get enough oxygen from the soil, so they stop absorbing nutrients from the soil, causing discoloration in the leaves.

Another common problem is excess moisture on the leaves. Water droplets can settle on the leaves and turn them white if they are left sitting there for too long.

This water can also lead to disease since moisture on plant leaves contributes to disease development.

4. Improper Cultural Control:

Sometimes even a lack of space or improper cultural control can result in white spots.

Cucumbers are sensitive plants, and if you don’t take proper care of them, white spots could appear on the leaves.

They prefer well-drained soil with a pH between 6 and 7. Plant them in full sun if you live in a warm climate, but give them afternoon shade if you live in a warmer area.

They need heat to develop properly, so plant them at least one week after the last frost date. Space each plant at least 1 foot apart so they have plenty of room to spread out their roots.

Water the soil around each plant regularly but avoid getting water on the leaves because it can cause fungus problems.

Here are the full details of the ideal growing environment for cucumbers.

5. Accidental Blanching:

One of the most common causes of cucumber leaves turning white is accidental blanching. Accidental blanching occurs when you cover the cucumbers with heavy foliage.

Some gardeners like to blanch their cucumbers by burying them in straw or otherwise preventing sunlight from reaching the fruit as it grows.

However, sometimes they accidentally blanch their plants by completely covering them with mulch or straw. This can prevent the roots from getting enough oxygen, causing white, pale leaves.

Accidental blanching will result in less chlorophyll in those leaves and white or yellowish color that is not desirable in cucumbers.

6. Natural Aging Process:

Cucumber plants naturally turn white as they age and begin producing seeds. When they begin producing seed pods, they take nourishment away from their production of fruit and reallocate it towards seed production.

This causes pale yellow or white-colored leaves.


There are a lot of possible reasons for white spots on cucumber leaves. so finding out the actual reason is crucial for the survival of the plant.

I hope, after reading this post, you’ll be able to identify the problem and take appropriate action.

With these easy-to-follow tips, you can ensure that your cucumber plants stay healthy and development-free.

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