Seeds germinate best in a warm, moist environment, and can be given the best possible conditions for growth through the use of heat mats. These mats sit under the seeds' planting bed and provide a subtle and constant warmth, stimulating healthy root growth. When used in conjunction with covered propagation systems, heat mats also help to regulate the humidity of the seedlings' grow space, allowing the warm soil to release its moisture into the air. Heats mats also allow seeds to germinate in low temperatures without needing increase the heat of the ambient air.