Why Are My Cucumber Leaves Turning Yellow?

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As we all know, cucumbers are refreshing summer treats that can provide you with a lot of vitamins and minerals and can also be very hydrating. Cucumber leaves are one of the most grown vegetables in the US and If the leaves are affected, they pose a problem. 

But why are my cucumber leaves turning yellow? There are several reasons for this, and there is not just one particular answer. But the common reasons why cucumber leaves might turn yellow include issues with the sunlight the plant is getting, bad soil, pests, issues with watering, etc.

In this article, we will discuss this in detail and also provide some practical solutions to yellowing cucumber leaves!

Why Are My Cucumber Leaves Turning Yellow?

Knowing why your cucumber leaves are turning yellow is the first step to fixing this problem. Some common reasons why cucumber leaves turn yellow include:

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1. Inadequate Amount of Sunlight 

If you notice that your cucumber leaves are beginning to turn yellow, you should check if the cucumber leaves are getting adequate sunlight.

Just like most other plants, cucumber leaves require sunlight for their healthy growth and development, and if that is absent, then your cucumber leaves are prone to yellowing. So if your cucumber leaves do not receive at least six hours of sunlight daily, it is prone to yellowing. 

The best solution to this problem is moving the plant to a location where it can get adequate sunlight. Doing this is possible mainly for plants planted in flower pots.

If you planted your cucumber to the ground, you could fix this issue by clearing up other plants blocking your cucumber leaves from getting the right amount of sunlight

3. Watering Issues, Too Much or Too Little 

As the old saying goes, too much or too little of everything is terrible and ensures that you do things in adequate proportion. 

It is a known fact that cucumber plants need water to mature correctly, but overwatering can also pose a serious issue. The shocking truth is that overwatering is an even more common cause of the yellowing of cucumber leaves than underwatering.

But that doesn’t mean underwatering would also not serve as an issue. Cucumber plants require a minimum of one or two inches of water every week for them to be able to grow, coupled with several other essential factors. 

If you are planting your cucumber in pots, then you should ensure that you create small holes so excess water can pass through. And also, ensure that you plant the cucumber in well-draining soil. 

3. Several Deficiencies with The Nutritional Composition 

Every soil needs an adequate amount of nutrients for the plant to thrive. When your plants do not get the required nutrients, they begin to struggle to reach their peak. 

So before planting your cucumber leaves, you need to use a soil meter to check if your plant has all the requirements for your plants to thrive. 

You do not have to worry if your soil is nutrient deficient. You can always add nutrients to your ground, so the first step is to be sure of the nutrition your soil has. 

Some deficiencies you would notice with your soil includes; 

  • Potassium Deficiency 

It is usual for cucumber leaves to require a higher amount of potassium as soon as they begin to flower. So if your plants do well when they are still growing without flowers, and start to turn yellow when flowers begin to appear, then there is a very high chance that your plant is struggling with potassium deficiency. 

Another more evident sign that this is the issue is that your plants would only turn yellow at the tip and edges. Seeing this doesn’t mean yellowing at other parts wouldn’t occur, but it would be too evident at the ends and edges. 

This is a straightforward solution to this problem. All you have to do is use a fertilizer with a very high amount of potassium. If you need this fertilizer to work quickly, ensure that it is a water-soluble fertilizer, it gets absorbed into the soil faster. 

  • Nitrogen Deficiency 

Nitrogen plays a massive role in the proper growth of plants, not just the cucumber leaves. Yellowing of the leaves of plants is very common when there is a nitrogen deficiency. 

So, if you notice that your leaves are beginning to turn yellow, you should check it for a deficiency in nitrogen because if you do not attend to this problem quickly, your plants may die faster. 

Generally, nitrogen is responsible for the general growth of your plants, most especially the foliage. Another way to know if nitrogen is the problem, you would notice that the vines of the cucumber plant would not be able to grow and crawl to support the system. 

Like when your plant is potassium deficient, you can correct this issue by adding nitrogen to your soil. We advise that you go for liquid-based nitrogen fertilizer. It works its way into the soil faster.  

Some other nutrient deficiencies include; 

  • Iron deficiencies
  • Zinc deficiencies

4. Cucumber Plant Diseases 

Besides the general diseases that affect plants, certain conditions only affect cucumber plants. All plants are susceptible to diseases, and the cucumber leaves plants are no different. 

Some common cucumber diseases your plants can experience include; 

  • The cucumber mosaic virus. You would notice that your cucumber leave plants would begin to wrinkle and starts getting curved downwards with yellow leaves. 

In this case, there is no known chemical solution yet, so all you have to do is pull the plant out of the soil so the disease does not affect other plants.

  • Downy mildew Is another severe cucumber disease that causes your cucumber leaves to develop yellow spots and turn brown. 

Get a liquid fungicide and spray it on your plant to fix this issue. So, keep your eye on your cucumber plants because the faster you notice the disease, the faster it is to treat. 

  • The fusarium wilt is a fungi infection usually caused by the fungus, Fusarium oxysproum. Some common symptoms of this fungi include yellowing the leaves or the leaves turning a dull grey with dark spots on the lower parts. 

There is no known cure for this plant since it affects the vascular tissues of your plants. You have to eliminate them, so they do not affect other plants. 

5. Pests 

Pests are not left out since the cucumber leaves are not immune to pest infestation. Some common problems that affect your cucumber leaves include spider mites, aphids, white flies, cucumber beetles, and southern corn rootworms. 

You can know if plants are behind your leaves’ yellowing by checking on the stems, leaves tops, and bottom, especially if these plants are curling. 

You can fix this issue by spraying your cucumber leaves plants with pesticides. 


There are several reasons why your cucumber leaves would turn yellow, but there are several solutions for most of the problems. 

To prevent the yellowing from happening, ensure that you provide your cucumber leaves with the adequate amount of light, water, and nutrients they need. Prevention Is said to be better than cure.

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