The leaves on bamboo plants can turn yellow whether the plant is potted or growing outdoors. There are two types of bamboo: clumping and running. While the culms or stems below ground can characteristically be yellow on a healthy bamboo plant, yellowing leaves are a sign that the bamboo plant is in distress. This distress can be caused by several factors.
Bamboo will grow best in a soil with a pH of 6.5. It may tolerate a lesser or higher soil pH, but poor quality soil without enough nutrients will produce a weak plant whose leaves may yellow and drop off. Similarly, if the soil is too dry or is waterlogged to the point where the bamboo canes are standing in water, the leaves can also turn yellow, curl up and drop off the plant.
Outdoor bamboo plants can be damaged by winter burn, cold temperatures and wind that kill the tops. The plant can die right to the ground, as the leaves and canes turn yellow and die. Potted bamboo plants should be brought inside before a hard frost. Outdoor bamboo should be planted where there is a windbreak. A bamboo plant that has winter burn will grow back, but it may be weaker and smaller than normal.
Spider mites damage bamboo plants by eating the leaves, causing spots and eventual yellowing and dying. You can see spider mites, their eggs and webs on the undersides of leaves by using a magnifying lens. The spider mite population tends to thrive in the warmer months and when pesticides are used against their biological predators. Removal of the infected plants and treating the new growth with insecticidal soaps or oils will remove the infestation.
Root damage on both clumping and running varieties of bamboo will adversely affect the plant's leaves, causing yellowing and drop off. Running bamboo has an extensive root system and grows quickly. The root system can spread over 30.5 m (100 feet) from the original plant. You may inadvertently damage the bamboo root system when you use lawn aerators, sprinkler heads, hoes and other gardening implements while landscaping and gardening.