Why Are Cucumber Leaves Turning Yellow?

Growing cucumbers is fun not until the plant’s leaves turn yellow. When the cucumber plants have many yellow leaves it shows that there is something affecting the growth of the plant.

Some signs will show up and the leaves problem of cucumbers must be fixed to keep the plants thriving and healthy. When there are no yellow leaves on the cucumber plants, they will grow better and can grow a lot of fruits. But what are the causes of this problem and why does it happen?

Why Are Cucumber Leaves Turning Yellow?

Nutrient Deficiencies

Nitrogen is essential for cucumber plants. It helps the leaves to grow better and healthier. When cucumber plants are lacking nitrogen leaves can turn yellow.

Nitrogen is important for the production of chlorophyll in the leaves. The chlorophyll makes the leaves green and when lacking it, leaves will become yellow.

So fertilizer rich in nitrogen must be added to the soil. Checking the soil elements can be checked by using a soil testing kit. Aside from nitrogen, iron also helps leaves stay green.

When the soil is rich in nitrogen and iron the leaves will stay green and healthy. It will help the plants grow more leaves which is important when they are still young.

But once the plants become more mature the nitrogen needs to be lessened and increase the application of phosphorus and potassium to increase flower and fruit yield.

Watering Problems

The cucumber plants need water but when overwatering happens it can cause yellowing of leaves. Too much water because of overwatering can make plants stressed.

Cucumber plants need around 1-1.5 inches of water per week. That amount of water is enough for the plants to thrive and grow well. Young cucumber plants need less water than a mature ones.

When a lot of water is given to the cucumber plants they cannot handle it and can cause root rot which can lead to yellow leaves on the plant.

There are times that heavy rain comes and it can also make the plant overwatered so it is better to make waterways to prevent cucumber plants from getting flooded.

Lacking water can also cause cucumber leaves to turn yellow. During summer the weather becomes hot and during this time cucumber plants need more water.

When the weather becomes hotter the water dries quicker so give cucumber plants water to make them hydrated. They can be watered early in the morning or late in the afternoon.

Lacking Sunlight

Cucumber plants need at least six hours of sunlight per day. Lacking sunlight can be a reason why there are yellow leaves on cucumbers.

Before growing cucumbers, make sure to find a good spot where sunlight is abundant. A spot where the sun is available for long hours. Cucumber leaves will become healthy when they get enough sunlight.

Even though cucumber vines are crawling and they can move to sunny areas, they still need a lot of sunlight when they are young. Young cucumber plants are small and they cannot reach the sun.

When those young cucumber plants don’t grow well, they will become stunted when they mature. 

Pest Problems

There are pests that can attack cucumber plants and cause yellow leaves like spider mites, whiteflies, and aphids.

Controlling these pests is needed to keep cucumber plants healthy. Pests can make the plants grow poor when they damage a lot of their parts so keep pests away from your cucumber plants. You can spray insecticidal soap to get rid of these pests.

Transplant Shock

Commonly cucumber plants are not being transplanted when they are already mature. When the vines are already crawling, moving them is not a good idea.

If mature cucumber plants are going to be transplanted they can have yellow leaves. Shock is more common for already mature plants than young plants which is why usually cucumber plants are being transplanted when they are still seedlings.

Cucumber seedlings don’t suffer shock and they do transplant well.

Aging Leaves

If there are only a few yellow leaves on a cucumber plant probably they are just aging leaves. The plant will grow new leaves and those leaves will get old.

It is a part of the cucumber plant growth cycle in which new leaves will grow and those old leaves will turn yellow, turn brown, and drop.

Observing the cucumber plant regularly will help to determine if those leaves are really old leaves or not.

How To Prevent Cucumber Leaves From Turning Yellow?

Preventing yellow leaves on cucumber plants is possible by making sure that the plants are getting enough water, sunlight, and nutrients.

Avoid cucumber plants to be overwatered and over-fertilized because too much water can cause stress and root rot, and over-fertilizing can burn plant roots which can cause yellow leaves. By preventing these things from happening, the cucumber plants will grow healthy.

Also, keep pests away from the plants, and when pests attack use insecticidal soap to get rid of them. You can also manually remove those yellow leaves from the cucumbers especially if only a few leaves are affected.

When a lot of leaves are affected, insecticides or pesticides can be used to get rid of these pests.

Cucumber Leaves Turning Yellow With Brown Spots

Downy mildew can cause leaves to have yellow and brown spots. When leaves are affected you can remove those leaves to prevent affecting other parts. This pathogen can also be treated by using fungicides.