The mat providesbottom heat which signals the seeds to begin germinating. Large enough for a standard starter tray, this 10" x 20" mat will work well with anyJiffy seed starting kit. Easy to use; simply plug it in and the mat will maintain the optimum temperature range for most seeds to germinate. Designed for indoor use only. Maintains a range of 70-85 degrees. After seeds have germinated and are sprouting up, remove seedling tray fromheat mat and place seedlings in a sunny window or under agrow light. | Ferry-Morse Seed Starting Heat Mat