Cucumber leaves turning yellow

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For a lot of gardeners, they enjoy growing their own cucumbers to add to a variety of dishes.

There is nothing better than enjoying the flavor of a crisp yet refreshing cucumber that you have grown yourself.

However, growing cucumbers doesn’t always go to plan. Occasionally, you may notice the leaves on your cucumbers becoming an unhealthy shade of yellow.

There are a number of reasons for this happening, from overwatering, lack of sunlight, diseases and pests.

All of these issues can be easily solved so that you have healthy cucumber plants to enjoy.

In this article, we have collected together the top 5 major causes of cucumber leaves turning yellow.

We will also discuss how you can easily solve these issues to have a healthy cucumber plant. 

Causes of your cucumber leaves turning yellow

The following are the top 5 reasons why cucumber leaves turn yellow:

  • Lack or overwatering
  • Soil Deficiencies
  • Pests affecting your plants
  • Lack of sunlight
  • Plant diseases

Below, we will discuss each of these issues and how you can solve it. Thus, this will prevent your cucumber leaves from turning yellow in the future. 

1. Water

Watering patio plants -

The most frequent reason for yellowing cucumber leaves is improper soil moisture. The problem with this is one of two things.

Yellow leaves may be caused by either too little or too much moisture.

Your cucumbers may respond by developing wilted, drooping stems and discolored leaves if you allow them to become overly dry.

However, maybe you were a touch over-enthusiastic with your watering.

If so, water-logged soil that prevents roots from obtaining vital nutrients may be the cause of yellow leaves.


To thrive, cucumbers require one to two inches of water every week.

Additionally, check that the area where you planted your cucumbers has sufficient drainage. Most cucumber plants respond well to drip watering.

Make sure the soil feels moist before watering. It’s not yet time to water if you can feel the moisture in the soil around 2–3 inches deep with your finger.

The soil shouldn’t be consistently damp because that will just cause more issues, including root or leaf disease.

2. Soil deficiency

Lawn soil

Making sure your soil is nutrient-rich to support the growth and well-being of your plants is an essential component of gardening.

When growing vegetables and fruits, this is a crucial aspect to keep in mind.

We advise you to undertake a soil test as soon as possible. You may find out what your soil is missing by performing a quick test.

With a fertilizer designed for your particular soil needs, you may quickly adjust the soil.

Iron deficiency

The new leaves of your cucumber plant will be yellow. Yet they will also have green veins if it is iron deficient.


This problem can be addressed by spraying a liquid iron solution on the cucumber plant’s leaves or by dusting granular iron all around the plant’s roots.

Potassium deficiency

When a cucumber plant starts to blossom, it typically needs more potassium. The leaves on your cucumber plant may begin turning yellow at the borders and tips as a result of a potassium shortage.


Use a fertilizer that is well-balanced to address this issue.

Nitrogen Deficiency 

Cucumber leaves frequently turn yellow as a result of a nitrogen shortage. The foliage and growth of plants are caused by nitrogen.

It helps maintain the leaves’ healthy appearance. You must immediately fix this problem, otherwise, your cucumber plants will perish. 


The most effective and simplest way to provide nitrogen to your cucumber plant’s soil is to sprinkle a few teaspoons of fertilizer. Usually, you will require a fertilizer using a 5-10-10 ratio.

Follow the instructions carefully when applying fertilizer. This is because if you add too much, then this will harm the cucumber plant and restrict it from growing cucumbers.

Ammonium nitrate can be added to your soil as the cucumber plant starts to blossom. It only needs a tablespoon to be added. Three weeks later, repeat this process. 

Another option is to surround your soil with a light covering of compost.

If a nitrogen deficiency is a reason for your cucumber’s yellow leaves, these remedies should help.

2. Pests

The cucumber plant is a favorite food source for many different pests. The sap in cucumber leaves is a favorite food source for white flies, spider mites, and aphids.

The cucumber leaves may become yellow whenever these insects start eating your cucumber leaves and plants.

Since these bugs have the potential to destroy the plant, you should absolutely get rid of them immediately. Insecticidal soap can be sprayed on the cucumber plant’s leaves to eliminate these pests.

Why are your cucumber leaves turning yellow? Discover 5 reasons and how to fix it

Potato leafhoppers

The Potato Leafhopper should be avoided because it poses the greatest threat to cucumber plants.  Potato leafhoppers consume the sap found in cucumber plant leaves as well.

They pump watery saliva, through the plant, which harms the leaves and turns them yellow. The plant’s leaves will eventually fall off.


Potato Leafhopper damage can be avoided in a number of ways. This is by applying an insecticide, using row covers, and supporting beneficial insects like ladybugs, lacewings, and tiny pirate bugs. These bugs will all consume potato leafhoppers.

3. Sunlight

Chlorophyll is responsible for the vivid green color of a healthy plant. This material absorbs sunlight and transforms it into energy that is beneficial to plants. Chlorophyll cannot do its job if your plants are not receiving enough sunlight. 

You’ll see yellow leaves, reduced development, and little to no blooms or fruit as a result.


You must ensure that you are providing enough sunlight. The majority of cucumber varieties prefer at least 6 hours each day in direct sunlight because they are a sun-loving crop. 

Try shifting your cucumber plants to a more sunny location if you’re growing them in containers. Additionally, trim as many overgrown branches as you can for in-ground gardens that are next to a tree that provides shade or restricted sunlight.

4. Diseases 

Cucumber plants are unfortunately susceptible to a number of diseases. This includes downy mildew, fusarium wilt, and cucumber mosaic virus.

Downy mildew

Pseudoperonospora cubensis is a pathogen responsible for downy mildew. Downy Mildew thrives in moist or muggy environments.

Yellow dots that appear on the cucumber leaves’ surface and eventually cause the entire leaf to become brown are symptoms of downy mildew

Fortunately, downy mildew cannot live on plant waste. This disease can only thrive on tissue from living plants.


You can try a few things to try to stop and solve this issue.

Choose cucumber types with a high level of downy mildew resistance. Then make sure that the cucumber plants are spaced apart to allow for adequate airflow and drying.

It is important that you spray or add fungicides once you begin noticing any disease symptoms. However, for fungicides to be effective, you need to catch it as soon as possible.

So keep a watchful eye out for any downy mildew symptoms on your cucumber plants. Any diseased plants should be removed as soon as possible. 

5. Fusarium Wilt

The fungus Fusarium oxysporum f. sp. cucumerinum, which causes fusarium wilt, can survive for a very long time in the soil.

It can survive as either persistent spores (chlamydospores) or in close proximity to plant waste. The vascular system is impacted by the fungus.

Damping-off is one symptom of fusarium wilt infection in cucumber plants. Plants that are older may exhibit stunting, yellowing and wilting.


Your cucumber plant will often die in 3 to 5 days if it starts to wilt. Fusarium wilt can appear at any stage of the growth cycle. Therefore, infected cucumber plants must be killed once they show symptoms.

Cucumber mosaic virus

Mottling, mild mosaic patterns, flecking, and fern leaf deformation on your cucumber plant are signs of cucumber mosaic virus

Aphids are the carriers of the cucumber mosaic virus, which can infect a plant in a matter of seconds. This can then spread to numerous plants within a few hours.


The bad news is that you will need to uproot the entire plant as well as any weeds that could potentially contain the cucumber mosaic virus. This is in order to eradicate the disease completely. 

The cucumber mosaic virus might persist in the soil and harm your plants the following season. So if this illness becomes an issue for you, pay attention to where and what you plant.

What other plants are good to be planted next to cucumber plants?

A couple of these problems can be avoided, especially when it comes to pests. This can be done by planting particular types of plants alongside your cucumber plants. 

Cucumbers do well with peas, onions, corn, radishes, beans, beets, and carrots as companion plants.

Sunflowers and marigolds are excellent companion plants because they deter insects and beetles that prey on cucumbers. Dill and oregano are also said to help ward off insects and other pests too. 


Numerous factors, including soil deficiency, cucumber plant-specific illnesses and pests, watering issues, and inadequate sunlight, can cause cucumber plants to become yellow.

We have gone through each of these causes of why your cucumber leaves are turning yellow. Alongside offering various solutions to help you fix them. 

We hope this article has been helpful. With this information, you will be able to ensure your cucumber plants are healthy and will continue to thrive. 

FAQs about cucumber leaves turning yellow

Will cucumber leaves turn any other color then yellow?

No. If the leaves are healthy, they should be a vibrant green color. If the leaves get burnt, they might turn black, however, yellow and vibrant green are the most common colors that the cucumber leaves may turn.

What plants can not be planted beside cucumber plants?

There are several plants that should not be planted near cucumber plants. These include:
-Aromatic herbs such as dill, fennel, and anise: These plants can stunt the growth of cucumber plants and cause the cucumbers to have a bitter taste.
-Walnut trees: The roots of walnut trees release a chemical called juglone, which can be toxic to many plants, including cucumbers.
-Nightshades plants: Eggplant, tomatoes, peppers are plants of the nightshade family and they are also known to release allelopathic chemicals, this can inhibit growth of cucumber and other plants nearby.
Potato: Potato plants can spread the disease known as mosaic virus to the cucumber plants
It’s always a good idea to research the specific needs and compatibility of the plants you want to grow together.

How long does it take to grow cucumber plants?

The time it takes for cucumber plants to reach maturity can vary depending on the variety and growing conditions. In general, cucumber plants grown from seed can take 50-70 days to reach maturity, while plants grown from transplants can take a bit less, around 40-50 days. These are rough estimates, some varieties of cucumber might take less time while some might take bit more time to reach maturity. Keep in mind that these estimates do not include the time it takes for the plants to produce fruit, which can take an additional 1-2 weeks.
It’s also important to note that the cucumber plants reach maturity faster when grown in warmer temperatures, whereas they tend to take longer time in colder climates, also the plant quality and care also play a vital role.



Want to learn more about cucumbers and their uses? Cucumbers are an amazing vegetable that can be used for anything including salads, pickles, and even on their own!

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Mary Jane Duford
Mary Jane Duford

Mary Jane Duford is a Master Gardener and founder of the gardening website Home for the Harvest. She has been featured by Better Homes & Gardens, Real Simple, Good Housekeeping, Mother Earth News, and the National Garden Bureau. Mary Jane lives with her family in the Okanagan Valley.