5 Reasons Your Cucumber Leaves Are Turning Yellow And How To Fix It
How to fix yellow cucumber leaves
If you spotted yellow leaves on your cucumber plants, don’t fret, there are several reasons for this and there are solutions to this common gardening problem.
The five reasons for cucumber leaves turning yellow include:
1. Deficiencies in the soil
2. Diseases that affect cucumber plants
3. Pests that affect cucumber plants
4. Watering problems
5. Insufficient sunlight
Below I will go into detail about each reason your cucumber leaves are turning yellow. Once you have identified the reason behind your yellow cucumber leaves, you can fix them and enjoy beautiful, homegrown cucumbers.
The items listed are accompanied by affiliate links, meaning I earn a small commission if a purchase is made through my links. This has no impact on the cost to the consumer. I link to products this way whenever possible, and it has no bearing on the products I choose to review or recommend.
The Culprits Behind Cucumber Leaves Turning Yellow
Deficiencies
An important part of gardening is making sure that your soil is rich in nutrients to help your plants grow and thrive. This is essential when you are growing fruits and vegetables.
The first thing I recommend is for you to conduct a soil test. By doing a soil test, you can figure out what is lacking in your soil so it can be amended. You can easily amend the soil with a fertilizer that is geared towards your specific needs.
Nitrogen Deficiency
It is common for cucumber leaves to yellow when there is a nitrogen deficiency. It is vital that you correct this issue or the cucumber plant can die.
Nitrogen is responsible for plant growth and foliage. It helps to keep the leaves looking healthy.
How can you add more nitrogen to the cucumber plant?
The best and easiest way is to add nitrogen to the soil of your cucumber plant is to add a couple of tablespoons of fertilizer. You want a fertilizer with a ratio of 5-10-10. Make sure to follow the directions when using fertilizer, as using too much can also do harm to the plant, and then you won’t produce cucumbers.
When the cucumber plant begins to flower you can add ammonium nitrate to the soil. All you need to add is a tablespoon. Repeat this 3 weeks later.
You can also try adding a thin layer of compost around your soil.
These solutions should rectify the yellow leaves if the cause is due to a nitrogen deficiency.
Potassium Deficiency
Cucumbers tend to need a higher amount of potassium when it begins to flower.
A possible sign that your cucumber plant has a potassium deficiency is that the leaves begin to turn yellow at the edges and tips.
To solve this problem, use a well-balanced fertilizer.
Iron Deficiency
If your cucumber plant is suffering from an iron deficiency you will notice that the new leaves are yellow but have green veins.
This issue can be remedied by either spraying the foliage on the cucumber plant with a liquid iron or by sprinkling granular iron around the roots of the plant.
By doing a soil test, you can figure out what is lacking in your soil so it can be amended.
Plant Diseases
Unfortunately, there are several diseases that are known to infect cucumber plants such as cucumber mosaic virus, fusarium wilt, and downy mildew.
Cucumber Mosaic Virus
If your cucumber plant has mild mosaic patterns, mottling, flecking, and fern leaf distortion this is an indicator of cucumber mosaic virus.
Cucumber mosaic virus is spread by aphids and unfortunately in the blink of an eye, the plant can be infected and in a few hours time, many plants can be infected with the virus.
The bad news is that to eliminate the disease you will have to remove the entire plant and any weeds that can harbor cucumber mosaic virus. Cucumber mosaic virus can live in the soil and affect your plants next year as well. So be mindful of what and where you plant if this disease ends up being your problem.
Fusarium Wilt
Fusarium wilt is caused by the fungus, Fusarium oxysporum f. sp. cucumerinum, which may persist for long periods in the soil as durable spores (chlamydospores) or in association with plant debris.
The fungus affects the vascular system.
Some signs that your cucumber plants have been infected with fusarium wilt is damping-off. Older plants might have yellowing, stunting, and wilting. If your cucumber plant begins to wilt, the plant will usually die in approximately 3-5 days.
Fusarium wilt can occur at any time in the growing cycle and unfortunately, once infected cucumber plants have it they must be removed.
Downy Mildew
Downy Mildew is a pathogen caused by Pseudoperonospora cubensis. It thrives in wet or humid conditions.
Some signs of downy mildew are yellow spots that form on the surface of cucumber leaves and that eventually turn the entire leaves brown. The leaf spots are angular bounded by leaf veins.
The good news is that downy mildew can’t survive on plant debris. It can only grow on living plant tissue.
In order to prevent and tackle this problem you should try:
Plant cucumber varieties that have a high resistance to downy mildew.
Space out your cucumber plants so that they have good air circulation and can dry out.
Apply fungicides if you see signs of disease. You must catch it early though for fungicides to work. So monitor your cucumber plants closely for any signs of downy mildew.
Remove any plants that have become infected.
RELATED: White Spots on Cucumber Leaves: What You Need to Know About Powdery Mildew
Pests
There are several types of pests that love to feast on the cucumber plant.
Spider mites, whiteflies, and aphids all enjoy feeding on the sap in the cucumber leaves. When these insects do this, this can turn the cucumber leaves yellow.
You definitely want to get rid of these bugs because they can kill the plant.
To get rid of these pests, you can spray insecticidal soap on the leaves of the cucumber plant.
You want to watch out for the Potato Leafhopper though as they are the most dangerous to cucumber plants.
Potato Leafhoppers also feed on the sap in the leaves of the cucumber plant. However, they inject a watery saliva that damages the leaves and causes them to turn yellow. Eventually, the leaves will fall off the plant.
To prevent damage from Potato Leafhoppers, you can treat them with an insecticide, use row covers, and encourage beneficial insects such as ladybugs, lacewings, and minute pirate bugs who eat potato leafhoppers.
RELATED: Plant Smarter, Not Harder: Starting Cucumber Seeds Indoors the Easy Way
Water Problems
Another source of cucumber leaves turning yellow is due to watering issues. Inconsistent watering can lead to problems. Cucumber needs about 1 to 2 inches of water each week to thrive. Also, make sure that you have good drainage where you plant your cucumbers. Drip irrigation works well for cucumber plants.
Not Enough Sunlight
Cucumbers love the sun! So make sure that they are planted in an area that gets at least 6 hours a day of sunlight. Some tend to do better when they get a full 8 hours of sun.
RELATED: Cucumber Transplant Shock: Reasons, Symptoms, and Solutions
Pin for later!
FAQS About Cucumber Plants
Should I cut off yellow cucumber leaves?
First, you need to determine the cause for the yellow leaves. Once you know what the cause is you can treat it. In some cases, the entire plant may have to be removed if it is infected with disease or severely damaged.
Can you overwater a cucumber plant?
Yes, you can overwater a cucumber plant. Cucumber plants need consistent watering of about 1 to 2 inches a week. They also need well-drained soil.
What are good companion plants for cucumbers?
Some good companion plants for cucumbers are peas, corn, beans, radishes, beets, carrots, and onions. Marigolds and sunflowers are also good companions as they repel beetles and insects that feed on cucumbers. Oregano and dill are also thought to help repel insects and pests as well.
RELATED: How to Grow Cucumbers in Grow Bags: A Beginner's Guide
Summing Up Why Do Cucumber Plants Turn Yellow?
Cucumber plants can turn yellow for various reasons including deficiencies in the soil, diseases and pests that affect cucumber plants, watering problems, and insufficient sunlight. The solutions outlined above depend on which problem you are dealing with. With knowledge, you can know what to look out for and how to help your cucumber plants grow and thrive.
