Both overwatering and underwatering will be detrimental to the health of your Sego Lily, but overwatering is a far more common issue. When this species receives too much water, its stems and leaves may begin to wilt and turn from green to yellow. Overwatering over a prolonged period may also lead to diseases such as root rot, mold, and mildew, all of which can kill your plant. Underwatering is far less common for the Sego Lily, as this plant has decent drought tolerance. However, underwatering remains a possibility, and when it occurs, you can expect to find that the leaves of your Sego Lily have become brittle and brown. It is crucial that you notice the signs of overwatering as soon as possible when caring for your Sego Lily. Some of the diseases that arise from overwatering, such as root rot, may not be correctable if you wait too long. If you see early signs of overwatering, you should reduce your watering schedule immediately. You may also want to assess the quality of soil in which your Sego Lily grows. If you find that the soil drains very poorly, you should replace it immediately with a loose, well-draining potting mix. On the other hand, if you find signs that your Sego Lily is receiving too little water, all you need to do is water more regularly until those signs have subsided.