Cucumber Leaves Turning Yellow: Why, Causes, Plant Diseases and How to Prevent - Absolute Gardener

Cucumber Leaves Turning Yellow: Why, Causes, Plant Diseases and How to Prevent

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Cucumber Leaves Turning Yellow

Cucumbers are a popular vegetable that many people love to eat. If your cucumber leaves are turning yellow, then you may be curious as to why cucumber leaves turn yellow and what can be done about it. Cucumbers need plenty of water and nutrients in order for them to grow properly, so if you notice cucumber leaves turning yellow, it is likely because the cucumbers are not receiving enough water or nutrients. This article will discuss the causes of cucumber leaf problems such as plant diseases and how they can be prevented with proper care!

Reason for Cucumber Leaves Turning Yellow

Cucumbers are very sensitive to the environment, so cucumber leaves turning yellow may be caused by a lack of nutrients or water. If cucumbers have been receiving too much nitrogen and not enough phosphorus, they will experience leaf chlorosis due to excessive production of plant hormones during days with high light intensity. In order for cucumber plants to thrive, cucumber leaves need at least 12 hours of light a day.

Cucumbers can also develop cucumber leaf problems if their roots are being suffocated by soil that has become compacted because it hasn’t been watered enough or the cucumbers have grown too large for the container they’re growing in. A lack of air circulation will cause cucumber leaves to turn yellow and will lead cucumbers to suffer from diseases.

Lastly, cucumbers can develop cucumber leaf problems if they are being attacked by pests such as aphids or cucumber beetles. These insects suck the plant’s sap out of the cucumbers which causes them to wilt and die out completely. The only way to stop cucumber leaves from turning yellow in such a case is to remove the plant and all of its cucumbers, rinse them off with water and then set up pest control by planting cucumbers either indoors or outdoors.

Cucumber Leaves Turning Yellow

Causes for  Cucumber Leaves Turning Yellow

These are some of the causes that cause cucumbers to turn yellow.

  • too much salt
  • heat stress
  • high boron in the soil
  • nutrient deficiency due to not getting enough calcium or phosphorus

How to Treat Cucumber Leaves Turning Yellow

Cucumber leaves can turn yellow for a variety of reasons. If cucumbers are being watered too often, the soil is poorly drained or they need more fertilizer, cucumbers will typically have symptoms of leaf turning yellow and downward curling cucumber vines. The best way to prevent these problems from happening is by using organic garden fertilizers and water cucumbers less often.

If the cucumber leaves are yellow and wilted, cucumbers may have a disease or insect problem such as powdery mildew. The best course of action is to pick cucumbers that were infected before they had chance to contaminate other cucumbers in the garden by using organic fungicide spray on cucumber vines.

If cucumber leaves are turning yellow and cucumbers have cucumber beetles, cucumbers should be sprayed with organic insecticide to reduce the number of cucumber beetles that will harm your garden in the future by destroying crops.

Plant Diseases

One of the possible cucumber plant diseases is cucumber mosaic virus. It can be spread by cucumbers, tomatoes and peppers through contaminated water or infected seedlings. Other cucumber leaf problems include powdery mildew, black rot, bacterial wilt (Pseudomonas syringae), scab (Corynespora cucumerina), cucumber beetle, cucumber mite and cucumber thrips.

Some of the cucumber plant diseases symptoms include yellow or brown variegated leaves with black spots on them, distorted vines or fruit; deformed leaf margins that can be seen as a “bull’s eye” pattern when viewed from above; flowers and cucumbers that have a darker green or yellowish-green color.

The cucumber plant disease cucumber mosaic virus can be prevented by planting cucumbers in a clean seedbed away from other cucurbitaceous plants and rotating crops. It is also important to purchase cucumbers that have been certified as disease-free or try to grow them organically without the use of pesticides, fungicides or herbicides. There are cucumber disease prevention strategies that you can use such as planting cucumbers in the ground, not growing them indoors or transplanting plants outdoors to avoid cucumber plant diseases caused by viruses, bacteria and fungi spores from spreading.

Prevention of Cucumber Leaves Turning Yellow


Cucumbers are cucurbits. Cucurbits have a sensitive root system and require well-draining soil to prevent cucumber leaves from turning yellow, plant diseases like damping off, and other cucumber problems. If your cucumber plants’ roots are not in the right conditions they will start to turn yellow which means that cucumbers are not getting the nutrients they need to thrive.

When cucumber leaves turn yellow it is a sign that there may be plant diseases or cucumber problems in your soil like over watering, root rot, and drainage issues (among others). If cucumbers’ roots don’t have enough oxygen then cucumber plants will absorb toxins from the soil and cucumber leaves will turn yellow.

Trying to fix cucumber leaf problems is a difficult task because they are caused by so many different factors, but there’s one thing you should keep in mind: Cucumbers need light soil for healthy root growth which means that cucumbers do not like wet soils or soils with high clay content.

If cucumber leaves are turning yellow because of the soil, then you need to amend it. If cucumbers’ roots have been restricted by drainage problems then cucumbers will not get enough oxygen from the air around them and cucumber leaves will turn yellow as a result. It’s important to use light soils for cucumbers because cucumbers like to be able to spread their roots in all directions.


Cucumbers need a lot of light. If cucumber plants are in areas that don’t get lots of sunlight, the leaves will turn yellow and could even die off. When cucumbers have too little light they often become bitter-tasting or watery and lose their flavour.


Dry cucumber leaves turning yellow are most often caused by drought. Cucumbers should be watered regularly, but not excessively – they do well with about an inch of water per week. Giving cucumbers too much water can lead to damping off disease, which is a fungus that kills the seedling from the ground up and stops it from being able to produce new roots or leaves.


Cucumbers require a lot of humidity and cucumber leaves turning yellow are often the result of low moisture in the air. The cucumber is one plant that does not like to dry out.


One of the most common reasons cucumber leaves turn yellow is due to an excessive amount of fertilizer. Excess nitrogen promotes lush green growth, but it also causes cucumbers vines and foliage to become tender and pale in colour. To prevent cucumber leaves from turning yellow with too much fertilizer, follow these steps:

  • apply a blend of natural fertilizers that include soluble nitrogen, phosphate and potassium
  • apply the fertilizer at a rate of one cup per cucumber plant. Applying more than this will make cucumbers soft and pale in colour
  • water thoroughly to allow the nutrients from the fertilizer to saturate into soil
  • water the cucumbers regularly and avoid making them sit in standing pools of water
  • An excess amount of salt can also cause cucumber leaves to turn yellow. To prevent cucumber leaves from turning yellow with too much salt, fertilise only once per month rather than every two weeks like you would if using chemical salts and invest money into a rain barrel to collect rainwater for cucumber plants


Pruning cucumbers are often required. The practice can either help to encourage leaf growth or reduce the size of cucumber leaves that are susceptible to disease and pests. When determining where to make cuts, be careful not to cut too deep into a cucumber plant’s root system as this will cause cucumber plants turning yellow due to inadequate cucumber plant water.

Cucumber Leaves Turning Yellow

Cucumber Leaves Turning Yellow Frequently Asked Questions

How do you fix yellow cucumber leaves?

Fertilize cucumber plants with high nitrogen fertilizer, such as 16-16-16. Reapply cucumber plant food monthly and mulch cucumbers with straw, hay or compost at the end of each season to prevent cucumber leaves from turning yellow due to sunburn and scorching.

Apply mulch around plants before hot weather sets in (before the heat index reaches 85 degrees). Provide cucumbers with a trellis or support to prevent cucumber leaves from turning yellow due to wind.

They also need enough water and nutrients; avoid overfertilizing cucumbers as this will cause cucumber plants not to take up proper amounts of iron, which can lead to cucumber leaves turning yellow. Avoid cultivating too deeply near cucumber plants.

Allow cucumbers to dry out between waterings; overwatering cucumbers will lead to yellow cucumber leaves and poor production. Use organic mulches around the base of cucumber plants that do not have a weed barrier as weeds compete with cucumbers for soil nutrients, leading to stunted growth.

What do Overwatered cucumbers look like?

Overwatered cucumbers often have wilted and flattened leaves. These cucumbers can also exhibit roots that are beginning to grow out of the containers they were originally planted in because there is not enough water for healthy plant growth.

Should you cut yellow leaves off cucumber plants?

Cucumber leaves turning yellow is not a disease, it’s just that cucumbers are beginning to age and the plant needs more space. It does not mean cucumbers have any diseases or pests on them.

You can cut cucumber leaves off if you want to but there isn’t really any need since cucumber plants only need cucumbers to grow.

Can yellow leaves turn green again?

Yes, cucumbers can go through a period of yellowing and then return to their normal colour when the plant is healthy. If your cucumber plants are turning yellow but you have already fertilized them this season (in fall or winter), there may be another problem at play. The following reasons could be the cause of cucumber leaves turning yellow.

Poor drainage in the cucumbers pot can lead to cucumbers with yellowing leaves because roots are not getting enough oxygen and nutrients from water that doesn’t drain well

Too much nitrogen fertilizer or too little phosphorus may also cause cucumbers to turn yellow, as will a lack of potassium.


Cucumber leaves turning yellow can be caused by a variety of factors. Poor drainage, high nitrogen levels, low phosphorus or potassium levels may all cause cucumbers to turn yellow in their early stages and then return to green when they have fertilized appropriately. We hope this article helped assure you that yellow spots on cucumber leaves are pretty normal and there’s no need to worry!

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