Like many of you, I was devasted when I saw yellow leaves on my bean plant. I was doing everything right, so why were my bean leaves turning yellow?
Bean plants are one of the first vegetable harvests of the year, and they provide pods well in the summer. This has given them the well-deserved reputation of the signals of the start of the warm season.
They bring the summer days with them. If you, like me, love having these summer friends in your garden, it may be disheartening to one day find them turning yellow.
But don't worry, there are many reasons behind yellowing bean leaves, and most are easy fixes. Yellowing is usually a case of improper soil, watering, or sunlight.
Unfortunately, there are a couple of more serious issues caused by disease and viruses which cause spots or edges of discoloration before affecting the entire leaf. I'll discuss how to deal with these problems too.
Beans are a popular garden choice as they produce food that is both a healthy green and a good protein source. There are three common garden beans:
- Bush beans The long classic green beans. These are great for canning, freezing, or eating fresh.
- Pole beans These dangling green pods grow from climbing vines and are great for drying or eating fresh.
- Snap peas These plants produce smaller beans and have been engineered to be less fibrous.
The information outlined here will be generally applicable to any of these.
For the most part, beans are not the fussiest about their soil. However, if you are running into problems, you may want to examine this. The ideal soil for green beans is silty and loamy, and the worst is one rich in clay.
Beans prefer neutral soil, between pH 5.5 and 7.5, and moving outside of that range can cause issues. You can test the soil pH with a test kit. Use a liming agent to bring the pH down if it's too alkaline.
You can also test for nutrients in the soil by using a soil test kit. A lack of nitrogen can cause the leaves to fade to a light green and then yellow. And a manganese deficiency can result in older leaves developing brown or yellow spots.
Address these problems by adding a fertilizer that contains the missing nutrient. Add a good quality compost too. With the correct additions, you should see your plant turning green again.
Maintain a good balance of water. Bean leaves may turn yellow if underwatered as it blocks the absorption of nutrients. Conversely, flooding the plants can trigger root rot which will also cause yellowing.
When you head out to water your bean plants, check the soil with a finger. If it’s dry, give the plant a good drink of water. If your finger gets wet, leave it to dry. The aim is to keep the soil moist but not waterlogged.
Beans love a lot of sunlight, and you want to aim for 6-8 hours a day, so be sure to plant them in a spot where they will receive a lot of light to keep them healthy.
If you are in a very sunny location, you can overdo the amount of sunlight. Like watering, you need to strike a balance.
If you think your beans may be getting too much sun, invest in some row covers to ensure they get the right amount of shade too.
If you are in a cold climate, another solution is to place your beans in a greenhouse to give them enough warmth to grow well. Make sure they get adequate sun protection in the greenhouse to avoid burning.
If you still find your bean plant has yellow leaves, it may be due to a disease. If blight is affecting the health of the plant, you will first see yellowing edges before the entire leaf turns yellow.
This is down to bacterium in the soil, and it quickly brings down the plant's health, as it now cannot use its leave to collect solar power. Although you cannot save this plant, you can prevent the spread to other plants.
Bacterial infections spread through moisture, so avoid contact with the plants when they are wet. Destroy affected plants and do not use their seeds. Controlling weeds and pests in the air will also help stop the infection’s spread.
Several bean mosaic viruses that appear in different parts of the country can infect your bean plant. Signs of this virus include multi-colored spots on the leaves, which eventually turn completely yellow or brown.
This virus will develop from injury, low nutrient levels, or spread by insects. Unfortunately, there isn’t a cure for mosaic viruses. Do not use the seeds or add plants to compost to control its spread.
There are preventative measures to avoid the virus in the future. Ensure the soil has plenty of nutrients, practice good pest control, and use mosaic resistant variants to avoid infection in another crop.
So there are the most common culprits behind the yellowing of leaves on your bean plants. I hope that this has helped you diagnose your crop’s condition.
Always ensure that your bean plant has proper light, water, and food. Buy virus and disease-resistant strains from reputable sellers, and make sure you work on pest control.
With these measures in place, you should be able to keep healthy bean plants easily in your garden and welcome the summer with a bountiful harvest.