Maintaining adequate temperatures is imperative for successful germination of seeds. These mats will warm the rooting area 10-20 F over ambient temperature. Helpful seed starting information is printed on the mat. For more precise control, use the Heat Mat Thermostat. Helps Germinate Seeds Faster Increase Seedling and Cutting Success Helpful Lighting, Watering and Planting Info Include Fits Under Common Seed Trays Available in three sizes: