Mint leaves turn black. What should I do if mint leaves have black spots?

1. Insufficient light

Mint is a long-day crop. Normally, ensure that there is sufficient light. If the environment is dark, the leaves of the plant may turn black. In this case, you need to put it in a sunny place so that it can receive light all day. If the light is particularly strong, you can use a 30% shading net to provide appropriate shade.

2. Too much watering

Mint likes moisture, and sufficient water is very helpful for the growth of its branches and leaves. However, if there is too much water and the environment is too humid, it may affect the breathing of the roots and cause the leaves to turn black. In this case, it is necessary to increase air circulation and loosen the soil appropriately to allow moisture to evaporate as quickly as possible. When watering, you should also pay attention to controlling the amount of water. Do not water too much, especially do not allow water to accumulate.

3. Excessive fertilization

Mint does not have a very high demand for fertilizer. As long as sufficient base fertilizer is applied when planting, top dressing is rarely needed during the growing period. If too much fertilizer is applied, it can easily cause fertilizer damage, burn the roots of the plant and turn the leaves black. If you encounter this problem, you need to remove the plant from the pot in time. After taking the plant out of the pot, wash off the old soil at the roots, check the condition of the roots, cut off the parts that have been burned and rotted, spray a little carbendazim for disinfection, and prepare to replant after it is air-dried.

4. Diseases

Some diseases can also cause mint leaves to turn black, such as rust and leaf spot. These diseases are usually caused by fungi, which will cause black spots on the surface of the leaves. In severe cases, they will cause them to wither and fall off, and may even cause the plant to die. When the plant is found to be diseased, the diseased leaves need to be cut off immediately and sprayed with Bordeaux mixture or other drugs for prevention and control.