Beans are easy vegetables to grow, but did you notice your green bean leaves turning yellow? You might be saying to yourself, why are my green bean plants turning yellow?
It is not uncommon to see some green bean leaves turn yellow, especially at the bottom of the plant during the growing season. Still, sometimes it can be more severe than others. When this happens, it can cause problems for you and your garden.
Here are some of the top reasons your beans might be turning yellow and tips on preventing these problems.
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8 Reasons Why Green Bean Plants Turning Yellow
Green bean plants are easy to grow, and they are a great addition to any garden. They are also a great source of vitamins and minerals.
If you notice your green bean plants turning yellow, it could signify that something is not correct.
Let’s dive and discover why your green bean leaves turn yellow and solutions to fix them.
1. Insufficient Sunlight
Green beans are a warm-season crop, and they need 6 to 8 hours of sunlight daily for optimum growth. If plants fail to get sufficient sunlight, leaves may not be able to produce chlorophyll, which is necessary for photosynthesis.
Chlorophyll is a green pigment that is produced by plants to absorb sunlight.
In the absence of chlorophyll, leaves cannot perform photosynthesis, resulting in yellowing and eventual death of the plant.
How To Fix It
If your seedlings are growing in a shady area, transplant them to a site that gets 6 to 8 hours of sun. However, if your plants are already planted and established, do not rip them out. They may not survive the transplanting.
You might not get an entire crop from a plant living in the shade, but it is still possible to get a few pods. Collect seeds from these plants. If the mother plant was producing in the shade, the seeds would definitely produce plants that thrive in the sun. So, collect these seeds for next year!
2. Bad Watering Habits
The green bean plants can turn yellow if you provide insufficient or too much water. Water acts as a vehicle to transport nutrients from roots to all plant parts.
- Insufficient watering will not allow plants to absorb water and nutrients. Without these, the plant will wilt and eventually die.
- Overwatering can suffocate plants. It will also keep roots constantly wet, which can cause roots to rot.
Both insufficient watering and overwatering can deprive green bean plants of nutrients. This will result in yellowing and, eventually, the death of the plant.
How to fix it
Allow the soil to dry between the watering intervals. To check if you need to water green bean plants, insert a stick to your finger 2 – 3 inches (5 – 8 cm) into the soil. If the soil sticks to the stick or your finger, do not water. If the soil feels dry, water your plants.
3. Temperature Fluctuations
Green beans thrive best in temperatures between 68 – 86 oF (20 – 30 oC). Lower temperatures will slow down the growth and could cause the yellowing of leaves. Very high temperatures can burn the leaves of green bean plants. This will also cause leaves to become yellow. However, it will be noticeably different discoloration. Leaves will look scorched.
How to fix it
- Cover your green bean plants with agricultural fleece if the weather is cold. It will protect them from the cold. This fleece allows water and light through and is also lightweight. It will not squash your seedlings and also keeps insects away. One thing to remember, it needs to be secured well, as the wind might blow it off.
- If you live in a really cold climate, consider planting green beans in the greenhouse.
- If you notice that the weather is very hot, ensure to provide enough sun protection to avoid heat damage. Cover green bean plants with a shade cloth. It is a mesh, usually made of loosely woven polyester with varying degrees of sun and wind protection.
4. Bad Soil Conditions
Green bean plants thrive best in well-drained, nutrient-rich, slightly acidic to neutral (6-7 pH) soil. The soil condition is considered bad when one of these causes leaves to be yellow.
How to fix it
- If the soil is too clayey, add agricultural sand to improve soil drainage. Add organic matter if the soil is too sandy and water retention is poor. To check if you need to improve soil drainage, perform a soil drainage test.
- Improve soil quality by adding organic matter or compost.
- Use a soil testing kit to check the soil pH. If the soil is acidic, add lime to raise the pH. If the soil is too alkaline, add sulfur to lower the pH.
To achieve the best results in growing green bean plants, drainage, nutrients, and pH should be checked and fixed if required before planting.
5. Lack of Nutrients
Like all plants, green beans need nutrients to grow and provide a good yield. Lack of nutrients can be a reason that causes the leaves of green beans to turn yellow. Contrarily, too many nutrients can burn your plants. So, do not overdo it!
If green bean plants suffer from manganese deficiency, it will cause yellowing and brown spots on the old leaves.
How to fix it
A soil testing kit can determine the nutrient deficiency. When you know which nutrient is missing, you can add it to the soil. Soon, you’ll see new growths indicating that the soil has the right amount of nutrients.
Pro Tip: Do not add too much nitrogen into your soil. Beans fix nitrogen in the soil and do not need any additional nitrogen. If too much nitrogen is added to the soil, bean plants will produce more leaves and vines but little fruit.
Overseeding is a gardening process that many people use. This method involves planting seeds and thinning them after they grow to the desired height. Overseeding is a great way to ensure that you get the maximum yield from your plants. However, if you overseed and will not thin the plant out, you will get overcrowded plants.
Green bean plants can grow very fast, and if not thinned in time, plants will not receive the necessary sunlight, nutrients, and air circulation. Beans are not very tolerant of overcrowding. This can cause problems such as yellowing of leaves and stunted growth.
How to fix it
Ensure that you provide enough space for your plants to grow. This will prevent overcrowding. Thin the plants to a distance of 8 to 12 inches (20-30 cm). This will allow air to circulate and prevent the growth of pests and diseases.
Green bean plants can be susceptible to pests. Compared to other plants, they have more insects interested in chewing parts of this plant. These pests are:
- Insects that eat holes or mine the foliage causing it to be yellow are bean leaf beetle, Mexican bean beetle, vegetable leafminer, and cutworm.
- Sap-sucking insects that can cause yellowing and deformation are aphids (bean aphid, cowpea aphid, melon aphid, potato aphid), potato leafhoppers, thrips, and two-spotted spider mites. 
How to fix it
- The best way to control pests is by inviting beneficial insects such as ladybugs, green lacewings, hoverflies, wasps, and many others. These will feed on garden pests and protect your plants.
- If you decide that you need to fix it quickly, use only organic products like neam oil or organic insecticidal soap to control pests. Remember, even organic pesticides can damage your beneficial insects.
- If you are not afraid to get your hands dirty, you can remove pests such as aphids by hand. Just squash them!
Alternaria leaf spot, Anthracnose, Bean rust, Black root rot, Fusarium root rot, White mold, Bacterial blight, Bacterial brown spot, Halo blight, Damping-off, Mosaic virus are diseases that affect green bean plants and can cause yellowing of leaves. Some are transmitted by bacteria, viruses, and others are transmitted by pests.
How to fix it
Not all infections have a cure, but all of them can be prevented. Learn about green bean plants viral and bacterial infections and how to avoid them and control them if possible.
One way or another, the best way to prevent any diseases is through good gardening practices and good garden hygiene.
Hopefully, your question, “Why do green bean plants turn yellow?” was answered. If you notice the yellowing of green bean plants’ leaves, consider all factors mentioned in the post. Mainly, avoid overwatering plants, ensure to check the nutrient levels, and amend the soil if needed. If you take care of these factors, leaves will be less likely to yellow.
If you enjoyed this article, you could find similar ones in our Gardening How To section.
Also, check out our “6 Green Bean Plant Stages” to learn more about how green beans grow.
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