In order to create optimal growing conditions in a greenhouse or grow tent, it is essential to monitor and regulate the humidity levels in addition to temperate levels. The optimum humidity range for growing plants is considered to be around 60%, with the 62% humidity control sachets from Boveda ideal for maintaining optimal humidity levels for growth. You will not run the risk of using "too many" sachets of Boveda, as the formula is designed to not let the humidity levels increase past the level specified. Using more sachets will only result in each sachet lasting longer. Once the pack stiffens, you will need to replace it, as it will be out of water.