This is a pretty vague question. What does the plant look like? There are many causes for a plant to die, and the physical appearance can give clues as to what is causing the plant to suffer. Are you growing in soil, or hydroponic? This is the first question I would need answered. One of the most common causes for plants to die in soil grows is poor drainage. Water needs to drain freely fron the roots to prevent rotting, and also to allow oxygen to reach the roots. Hydroponic grows need clean nutrient solutions, and solution temperatures need to be kept at constant temperatures. Over feeding can be the next cause. Different nutrients produce different symptoms, so it is hard to say if this is your problem. I suggest, in either grow type, flushing the medium with clean water, and see if that helps. Any info you have would help!
