Cucumber Leaves Turning Brown

If you’re like most gardeners, you probably enjoy growing cucumbers. They’re a delicious and healthy snack, and they’re easy to grow. However, the process of growing cucumbers doesn’t always go to plan…

If you notice that the leaves on your cucumber plants are turning brown, it’s important to take action. Brown leaves can be a sign of disease or stress, and if left untreated, they can kill your plant.

Why Are My Cucumber Leaves Turning Brown?

Fungal infections, insects, overwatering, leaf burn, and nutritional inadequacies are all common causes of brown leaves on cucumber plants. The discoloration will be based on the cause. For example, crispy leaves can be a sign of too much sunlight exposure, while brown spots can indicate a fungal infection.

I will now talk about each of these causes in more detail. Hopefully, by the end of this article, you’ll know why your cucumber leaves are turning brown and what you can do to fix the problem.

Browning Cucumber Leaves from Fungal Infection

The first potential reason for your cucumber leaves turning brown is a fungal infection. Fungal infections are common in cucumber plants and can cause the leaves to turn brown (or sometimes yellow). The most common type of cucumber leaf fungus is blight, which can cause brown or yellow spots on the leaves.

Fungal issues usually occur when the weather is warm and humid. To prevent cucumber leaf fungi, make sure to water your plants in the morning so that the leaves have time to dry before nightfall. Avoid overhead watering, which can spread the fungus. If you notice brown or yellow spots on the leaves, remove them immediately and destroy them.

You can also treat fungal infections with a fungicide. Be sure to follow the instructions on the package and apply the fungicide according to the schedule. Neem oil (Amazon link) is a natural fungicide that can be used to treat cucumber leaf fungi.

Cucumber Leaf Blight
Cucumber Leaf Blight

Browning Cucumber Leaves from Incorrect Watering

Overwatering is another common cause of cucumber leaves turning brown. When cucumber plants are overwatered, the roots can’t get the oxygen they need to function properly. This causes the leaves to turn brown and eventually die.

If you suspect that overwatering is causing your cucumber leaves to turn brown, check the soil before watering. If the top inch of soil is dry, it’s time to water. Be sure to water at the base of the plant and avoid getting water on the leaves.

It’s also important to make sure that your cucumber plants have good drainage. If the roots are sitting in water, they will suffocate and the plant will die. To improve drainage, add sand or perlite to the soil.

Browning Cucumber Leaves from Pests

Pests are another common cause of cucumber leaves turning brown. Aphids, cucumber beetles, and spider mites are all common pests that can damage cucumber plants. These pests suck the sap from the leaves, which causes them to turn yellow or brown.

If you suspect that pests are causing your cucumber leaves to turn brown, check the underside of the leaves for small bugs. They may even be hiding in the crevices. If you find pests, you can remove them by hand or treat them with an organic pesticide.

There are also some natural ways to get rid of pests. You can make a homemade insecticide by mixing water and dish soap. Another option is to use neem oil (Amazon link), which is a natural pesticide that’s safe for humans and animals.

Beneficial insects, such as ladybugs and lacewings, can also help to control pests. These insects will eat the pests that are damaging your cucumber plants.

Browning Cucumber Leaves from Leaf Burn

The sun is so powerful that it can actually burn the leaves of cucumber plants. This is called leaf burn and it results in dry, brown patches on the leaves.

If you think that leaf burn is causing your cucumber leaves to turn brown, move the plants to a shadier spot where they will get less direct sunlight. If the leaf burn is severe, you may need to cut off the affected leaves. This will help the plant to focus its energy on new growth.

You could also block the sun with a white cloth or row cover. This will protect the leaves from the sun’s rays and prevent further damage. Personally, I like to use a tarp during the hot summer months if my cucumber plants are getting too much sun.

Browning Cucumber Leaves from Nutrient Deficiencies

Cucumber leaves need certain nutrients to stay healthy. If they don’t get enough of these nutrients, they will start to turn brown. The most common nutrient deficiencies that cause cucumber leaves to turn brown are nitrogen and potassium.

If you think that a nutrient deficiency is causing your cucumber leaves to turn brown, test the soil and add amendments as needed. You can also give the plants foliar feed, which is a liquid solution that’s applied to the leaves. This will help the plant to absorb the nutrients it needs.

I recommend using a 3-4-4 fertilizer like Espoma Organic Garden-Tone 3-4-4 Organic Fertilizer, which I have successfully used for many years. You can find it on Amazon or at your local garden center.

Will Brown Cucumber Leaves Turn Green Again?

It is unlikely for brown cucumber leaves to turn green again. Once the leaves have turned brown, they are usually damaged beyond repair. The best thing you can do is to remove the brown leaves and focus on new growth.

If you want to prevent cucumber leaves from turning brown in the future, be sure to water them at the base of the plant and avoid getting water on the leaves. You should also make sure that your cucumber plants have good drainage and add amendments to the soil as needed. Finally, you can protect the leaves from the sun by using a white cloth or row cover.

Should I Remove Brown Leaves from My Cucumber?

I recommend removing badly damaged leaves and those infected by fungal diseases. However, you don’t need to remove every single brown leaf. A few brown leaves will not hurt your cucumber plant and will eventually fall off on their own.


To conclude, there are several reasons why cucumber leaves turn brown. The most common causes are pests, leaf burn, and nutrient deficiencies. If you can identify the cause of the problem, you can take steps to correct it. In most cases, however, the best thing you can do is to focus on new growth and remove the damaged leaves.

I hope you found this article helpful. If you have any questions, please leave a comment below and I will be happy to help.

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