Bamboo plants are hearty and easy to take care of, but sometimes even the greenest of thumbs can loose a plant to disease or improper growing conditions. In most cases, a yellow stem means your plant is already past the point of saving, especially if the yellow stems are also soft or mushy. In some instances, bamboo first aid will do the trick and bring your plant back from the edge.
Trim away the yellow parts of the stem. If the yellowing occurs just at the top of the stem, there may be time to save your plant. Locate the node by looking for one of the vertical rings around the stem. Use pruning shears or sharp scissors to make a clean cut on the stem at the node just below the yellow spot. Cut just above the node and discard the yellowing portion.
Correct your plant's water conditions to prevent more yellowing. Use purified water as a common source of stem yellowing is chemical residue in the soil left behind by tap water.
Change your plant's lighting conditions. Tall, yellowing and spindly plants often indicate you plant is not getting enough sun. If your stem is still thick and is just beginning to yellow, it could be sunburn. Move it to a place where it gets indirect or filtered sunlight to see if this corrects the yellowing.
Fertilize with care. If you regularly fertilize your bamboo plant, this could be the cause of your yellow stems. Bamboo plants only need sunlight and water, not large amounts of nutrients, to grow and make energy. A few drops of aquarium plant food once per year are sufficient. If you have never fertilized you plant, do so now to provide a boost.
Create a new plant from clippings if the yellow spots occur toward the bottom of the stem. To do this, cut away the top, healthy part of the plant above the node. Remove the old plant with the yellow stem from the container and replace it with your clipping. It will sprout roots and grow into a new bamboo plant.