If you’re concerned about your green bean leaves turning yellow then you’ve come to the right place.
It is usually caused by poor soil quality, improper fertilization or over/underwatering. In this guide we’ll break down 8 reasons alongside the solutions so you can get your green bean plant back to full health as soon as possible.
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8 Top Reasons Why Your Green Bean Leaves Are Turning Yellow
Improper watering, issues with sun exposure, and poor soil can all cause the plant’s leaves to turn yellow.
They can also be affected by pests, like aphids, viruses, and bacteria. Now that you have an idea of the problems that can plague green bean plants, let’s take a closer look.
1. Poor Soil
There are a few factors you’ll need to consider when determining if your soil is the cause of your green beans woes. Green beans aren’t really picky, and will grow well in most types of soil.
They prefer sandy or silty soil, but they will grow in nearly any soil, except for clay-heavy soil.
If the soil isn’t well-draining, this can lead to root rot. This is one of the reasons beans prefer loamy or sandy soil.
The ph is also important. Green beans prefer soil that’s neutral or slightly alkaline. It thrives in a ph of 5.5 to 7.5. If the soil is too acidic, this can also cause the leaves to turn yellow.
2. Over or Under Fertilization
To get the best from your beans, you’ll need to fertilize them. Just like humans, plants need nutrients. They get these from the soil. Adding fertilizer to the soil is much like you taking a vitamin. It can fill in any nutritional gaps.
Signs of Over or Under Fertilization
If your green beans are under-fertilized, the leaves will be yellow but the veins will be green. This is because the leaves are the last to receive nutrients.
If there’s not enough nitrogen, it can cause the leaves to be light green or yellow in color. Manganese deficiency can cause the older leaves to turn yellow. It can also cause brown spots on the leaves.
If your beans are over-fertilized, the lower leaves will turn yellow. The margins and tips of the leaves may turn brown.
3. Fixing Fertilization Issues
The first step to fixing fertilization issues is to have the soil tested. This will tell you for certain if your plant is lacking in certain nutrients, or if it’s getting too much fertilizer.
If your green beans are missing nutrients, purchase a fertilizer that meets their needs. Be sure to follow the directions when applying fertilizer. Compost can also help your beans get the nutrition they need.
If over-fertilization is the culprit, you can leach the soil. To do this, water your plants deeply. This will wash some of the excess nutrients from the soil. You may need to repeat the process a few hours to a day later.
4. Over or Under Watering
Over or underwatering can also cause your green bean leaves to turn yellow. Underwatering can prevent your plants from getting the nutrition and hydration that they need.
However, overwatering also causes problems. If the soil is too wet, the roots can’t pull in nutrition properly. Over time, over-watering can lead to root rot.
Root rot is caused by a fungus which attacks the plant’s roots, causing them to rot. The roots become brown and mushy, and can no longer function.
Signs of Over or Under Watering
Both these issues can cause yellowing leaves. They also lead to stunted or slow growth and wilting. If they are underwatered, the leaves will feel dry or papery. If they are overwatered, the leaves will feel normal, or slightly softer than normal.
One of the easiest ways to determine if there’s a watering problem is to check the soil. If the soil is very dry, your plants are likely underwatered. If they are overwatered, the ground will be waterlogged or very moist.
Watering Beans Correctly
Both watering issues can usually be remedied by watering your beans correctly. If root rot takes hold, the plants may not survive, however. Replanting the beans in another area after trimming away the dead roots gives them the best chance, but this usually isn’t feasible in the garden.
It’s much easier to prevent root rot by not overwatering. If underwatering is the cause, the plants should look much better after watering.
Most beans need 1 inch of water per week. When watering, try to avoid splashing soil onto the leaves. To determine if your beans need to be watered, stick your finger into the soil. If the top inch is dry, it’s time to water the beans.
4. Improper Sun Exposure
Improper sun exposure can also cause problems for your bean plants. Too much or too little sun can cause your beans’ leaves to turn yellow.
Too much sun can cause the leaves to burn. Too little sun reduces the plant’s ability to photosynthesize. Without proper photosynthesis, your plant can’t make the food they need.
Signs of Improper Sun Exposure
If your plants leaves are turning yellow, sun exposure might be the issue. Beans need 6 to 8 hours of sunlight a day. If they are getting less than that, they need more sun exposure.
If they are getting significantly more than that, they may be getting too much sun.
Remedying Sun Exposure
If your beans aren’t getting enough sun, the only option is to move them to another area of the garden. If too much sun is the problem, you can use row covers. This allows you to prevent your beans from getting too much sun.
Once you balance out the amount of sunlight your beans get, you can expect the new growth to be green and healthy.
5. Bean Blight
Bean blight is by far the most common bacterial disease that can affect beans. There are two types of bean blight. These are common blight and halo blight.
Signs of Bean Blight
One sign of common bean blight is misshapen leaves or bean pods. The leaves will develop small wet spots. Eventually, they dry out and grow in size. They become brown and papery, with a yellow border around the spots.
Halo bean blight has similar symptoms. However, the yellow around the spot is much larger. It looks like a halo, hence it’s name. The spots themselves are smaller than in common blight.
Prevention and Treatment
Prevention and treatment are essentially the same in this case. First, you’ll want to avoid touching the leaves when they are wet. Be sure to keep pests away from your beans. Whiteflies and beetles can spread the disease.
Copper bactericides are great for preventing blight. It may treat blight if applied early as well. However, it’s usually best to remove and destroy affected plants to avoid them spreading to other plants.
7. Aphids
Aphids cause yellow, misshaped, or curled leaves. This occurs because the insects feed on the leaves. You may see a sticky substance on the leaves or stems of the plants. This is the waste from the aphid.
You may be able to spot them, but they are small. They can be white, black, brown, gray, yellow, light green, or pink.
Treating Aphids
One way to remove aphids is to spray the plants with a hose. This will remove the aphids from the plant. Insecticidal soap or horticultural oil will kill aphids and help prevent reinfestation.
If aphids are still a problem, you can use a pesticide containing Imidacloprid. Continue reapplying until you’ve eliminated the aphids.
8. Mosaic Virus
The mosaic virus is spread by the most common pest of green beans, aphids. Just like blight, there are two common types of mosaic virus. These are the common mosaic virus (BCMV) and the bean yellow mosaic virus (BYMV).
BCMV will cause a yellow mosaic pattern on the leaves. Over time, they will warp and pucker, which can cause them to roll up. BYMV has similar symptoms, but the yellow will be more prominent. It also causes the leaves to droop.
Treating Mosaic Virus
Unfortunately, there’s no treatment for mosaic virus. Your only option is to destroy the affected plants to prevent the disease from spreading. Controlling aphids can reduce the risk of the virus.
In Summary
Green beans should be green. If they are yellow, this indicates a problem with your plants. To remedy the problem and save your crop, determine the cause of the yellowing.
Then, you can take the necessary steps to treat it. Your beans will be back to normal in no time, and you’ll be able to enjoy the fruits of your labor.
(Header Image Credit – Cheryl Colan)
