Why Your Cucumber Leaves Are Turning Yellow - Reasons & How to Solve

Written by Ivy

Jan 06 2023

Why Your Cucumber Leaves Are Turning Yellow - Reasons & How to Solve

Don't worry if you noticed yellow leaves on your cucumber plants; there are several causes for this and fixes for this typical gardening issue.

I'll go into more detail about each cause of your cucumber leaves turning yellow below. You can correct the issue and enjoy lovely, homegrown cucumbers once you've determined what is causing your cucumber leaves to turn yellow.

Five Reasons for Cucumber Leaves Turning Yellow

1. Deficiencies in the soil

2. Diseases that affect cucumber plants

3. Pests that affect cucumber plants

4. Watering problems

5. Insufficient sunlight

Why Are My Cucumber Leaves Turning Yellow?

Chlorophyll, the substance in plants that gives that distinct green color and is necessary for converting sunlight into energy, could be the cause of the loss of green coloration. Chlorosis is the loss of chlorophyll, and it can spell doom for your cucumber plant.

Of course, the problem can be fixed, but the first step is to identify the precise reason for the chlorosis in the first place. Several different factors, which we discuss below, may be to blame for the discoloration.

Water Problems

Like any plant, cucumbers can suffer from excessive moisture. Only 1 to 2 inches of water per week are required for cucumbers. Too much water could lead to oxygen-deprived roots, which, according to GardeningVibe, can cause the leaves to turn yellow or wilt. The issue may be with soil drainage, which can be fixed by aerating the soil with sand or by growing your cucumbers in raised gardening boxes. Thoughtfully keep in mind that underwatering can also result in wilting.

Soil Problems

Cucumbers are notoriously heavy feeders when it comes to soil nutrients, and according to SFGate, their leaves can turn yellow if they aren't getting enough nitrogen or potassium in their "diet." When it comes to the growth of plants, nitrogen is a crucial nutrient. In order to maintain those leaves' health, fullness, and greenness, it promotes foliage growth.

You can stop the yellowing by adding nitrogen to the soil, which you can do by incorporating compost, coffee grounds, or other nitrogen-rich fertilizers. Lack of phosphorus may be the cause of your leaves turning a dark yellow or bronze color. It won't be difficult to miss because this kind of deficiency will lead to decreased fruit production. If so, look for organic fertilizers that are high in phosphorus.

You may want to spend some time preparing the soil for gardening before you plant the following year because either of these deficiencies could indicate soil issues throughout your yard.

3. Why Your Cucumber Leaves Are Turning Yellow2

Cucumber Plant Diseases

Cucumber plants have a few common diseases that like to attack and can result in yellowing leaves, but all plants are susceptible to plant diseases.

Cucumber Mosaic Virus

  • Symptoms: Wrinkled leaves curved downwards, brittle, yellow spots

Cucumber mosaic virus is present if you see a light mosaic pattern, mottling, or flecking on your cucumber leaves.

This virus is spread by aphids, and it is possible that all of your plants will become ill within a few hours. The bad news is that you can only remove all of the weeds and plants in that area because this is a virus, which makes it even worse for your garden.

If you plant cucumbers back in the same spot, the cucumber mosaic virus will likely remain in the soil for at least a year and could infect your plants the following year. Crop rotation is crucial for this reason!

Remove all the impacted plants as a solution. You don't want to leave any infected plants in your garden since there are no chemical cures for this.

Downy Mildew

  • Symptoms: The leaves have brownish spots of yellow on them. The undersides of the leaves are covered in gray fuzz.

Downy mildew, a pathogen that thrives in moist, humid environments, is another troublesome cucumber disease. To avoid this bothersome disease, you should always check that your plants have air circulation.

The cucumber leaves will eventually turn brown after developing yellow sports on their surface. Angled leaf spots with leaf veins enclosing them.

Since downy mildew rarely thrives on plant debris, you can try to solve this issue. The likelihood of it spending the winter in your garden is therefore remote.

If you find that your cucumber leaves turn yellow, grab a liquid fungicide and spray it on your plants. This illness is easier to treat the earlier it is discovered.

Fusarium Wilt

  • Symptoms: Some leaves are turning yellow, while others are becoming dull gray-green. On the lower portion of the stem, there are dark spots.

Fusarium wilt is a fungal infection caused by the fungus Fusarium oxysproum. Due to the spores' long lifespan and potential for survival in plant debris, it is possible for this fungus to survive in the soil for extended periods of time.

Your plants will die as a result of this fungus because it affects their vascular system. You must get rid of any infected plants from your garden.

Young plants may experience damping off due to fusarium wilt. Older plants may have yellowing leaves, stunted growth, and wilting. The plants will perish within a week if they begin to wilt. To stop the spread of this fungus in your garden, it is best to rip them out.

Sunlight Problems

The majority of us are aware of the importance of planting cucumbers in a location that receives plenty of sunlight, but yellowing and drooping leaves may indicate that your cucumbers aren't getting nearly enough sun. Try relocating them if you have reason to believe this is the case so they can receive at least six hours of direct sunlight each day.

Pest Problems

According to GardeningVibe, insects and other garden pests are a common cause of leaf discoloration. Many garden pests are common, including aphids, whiteflies, potato leafhoppers, and spider mites. Numerous of these pests leave behind small, yellow patches on cucumber leaves after sucking the nutrients and sap out of them.

Plant specialists advise using insecticides on these kinds of bugs, but we suggest using a homemade or natural insecticide rather than a potentially toxic one. To reduce the number of insect pests that can make your garden their home, you could also completely remove all the weeds and other grasses from your vegetable patch.

As you can see, there are numerous causes of chlorosis as well as an equal number of treatments.

Spider Mites

For cucumber plants, spider mites can result in a variety of issues. They leave a silver web on the leaves after sucking the sap out of them while hanging on the underside of the leaves.

Infestations of your plants by mites usually occur in hot, dry weather between late June and August when they first appear on plants. The tiny adult spider mites range in color from yellow to dark red.

The reason why cucumber leaves turn yellow is because spider mites feed on the leaves. The leaves could dry out and fall off the plant during severe infestations.

You can treat a spider mite infestation by doing the following.

  • Spray the affected plants with neem oil, which is not a harmful product to your plants or you!
  • Try a spray designed for spider mites; this Bonide Mites X-Ready is a highly-rated choice.
  • Apply insecticidal soap to your plants, or try a homemade insecticide soap.

Apply to the top and bottom of the leaves regardless of which of these products you choose to use. Multiple applications may be necessary for severe infestations.


Cucumber plants are one of the many plants that are vulnerable to aphid infestations. These voracious pests sap the lifeblood from your plants, leaving behind a honeydew-like residue. You really don't want honeydew because it attracts ants and moldy black soot.

Aphids are absurdly small, oval-shaped insects that are frequently difficult to see because of their green color. The majority of them are usually green, though occasionally they could be red or black.

Additionally, aphids usually reside on the underside of leaves, making them more difficult to identify when examining your plants.

Aphid infestations typically only become a problem if they become overly numerous. At that point, I advise employing one of these solutions to get rid of these pesky pests.


If you have a significant infestation of whiteflies on your plants, they are another sap-sucking pest that will harm your plants. These insects have wings and white bodies.

These insects frequently fly out when you shake your plant, indicating a whitefly infestation.

Whiteflies can be controlled with the aforementioned products and another one is also an option if you have a garden with these pests. Whiteflies can be managed effectively without spraying your garden with chemicals by using reflective mulches.

Cucumber Beetle

Cucumber beetles are a pest that you don't want to have on your plants. Your plants, including your squash plants, will be destroyed by them, and the leaves will become a lacy skeleton of holes.

Cucumber beetles also frequently spread harmful plant diseases, which is a problem. Therefore, it is in your best interest to act as soon as you see a single cucumber beetle. Remove the beetle from your plants and place it in a cup of soapy water.

If you find cucumber beetles in your garden, you can also try some other options.

  • In your garden, release beneficial insects. Cucumber beetles are a favorite food of braconid wasps.
  • Mulching the plants with a thick layer of straw also aids in halting the beetles' migration.
  • Use floating row covers early in the season, after transplanting the seedlings into your garden, to prevent the young pests from landing on your cucumber plants. To allow for pollination, make sure to take off any floating row covers before the plants bloom.
Also Read: How to Grow Cucumber on the Balcony

How to Stop Cucumber Leaves from Turning Yellow

One way to ensure the success of your fruit is to know when to plant the cucumber seeds, but developing a care routine is just as important. The advice of the experts is given below.

1. Maximise Sunlight

For optimal health and to prevent fading, your cucumber plants should receive at least six hours of direct sunlight each day. If your cucumbers aren't getting enough sunlight, they'll probably droop and the leaves will start to yellow. Tom advises shifting your cucumbers from shady areas of your garden to a sunnier one (whenever possible).

2. Avoid Overwatering

Overwatering is one of the most common reasons your cucumber leaves turn yellow. To ensure a plant's success, you must know when to water it, but when is the ideal time to do so? The expert advises watering early in the day and avoiding the leaves because doing so encourages diseases. The best way to water cucumber plants is using a drip irrigation system or soaker hose. In order to prevent your crop from drowning, you can use this to monitor the water levels.

3. Monitor Nutrients in the Soil

The diet of your cucumber plant is yet another critical factor in the yellowing problem. 'Tom advises that you should make sure the cucumber plant is receiving the proper soil nutrients. 'In order to promote growth in foliage and maintain the leaves' health and greenness, they particularly enjoy the two nutrients potassium and nitrogen.

Investing in a fertilizer that provides the soil with all the nutrients your cucumbers require will ensure they have a healthy diet.

Should I Cut Yellow Leaves Off Cucumber Plant?

Yes, it is preferable to remove any leaves that have turned yellow as they might prevent light from reaching the fruit's healthy portion. Additionally, it will promote air circulation, which is good for the plant as a whole. To ensure a tasty crop, it's crucial to continue with the prevention measures above after the leaves have been removed.

What Do Overwatered Cucumbers Look Like?

Cucumbers that are overwatered frequently start to develop yellowing leaves. As Emma notes, finding the ideal water balance is crucial to the success of your fruit, and if you overwater them, your leaves will suffer. To prevent this, water your plants gradually in the morning or install a drip irrigation system that continuously checks the water level. (Read More:  Signs of Overwatering Cucumbers & How to Fix)


By removing yellow cucumber leaves, you can stop the disease from spreading if you think it is the cause of the yellowing. Pruning enhances air circulation, which helps fend off fungus-related diseases.

Consider removing only the worst-affected leaves and leaving the better-looking ones behind if all of your leaves are beginning to yellow. Your plant needs its leaves, which act as its solar panels, to convert sunlight into the sugars that provide for its needs.

It can take a lot of research, guesswork, and experimentation to determine why your cucumber leaves have turned yellow, so be prepared for a journey filled with visual checks. The procedure may be difficult.

However, the most challenging issues are frequently our best teachers. When you are enjoying the abundant harvest of your healthy cucumber plants, all of the effort seems to have been worthwhile.

FAQs About Cucumber Leaves Turning Yellow

Should I Cut Off Yellow Cucumber Leaves?

Finding the reason for the yellowing cucumber leaves is the first thing you need to do. There is no need to remove the leaves if the reason for the yellowing is environmental problems or nutrient deficiencies. To stop the spread of a disease or pest infestation, however, the leaves may be removed from the plant.

How Often Should Cucumbers Be Watered?

One to two inches of water per week are required for cucumber plants. According to the outside temperature and humidity levels, that typically means you should water every two to three days.