Maintain the ideal growing temperature using the Viagrow Seed Propagating Seedling Heat Mat. Studies have proven that plants with a root zone that is kept warm thrive and propagate at a much faster rate than plants that do not. Simply place the seedling heat mat on a flat, dry surface under a seedling tray and plug the cord into a 120V outlet. For best results, use propagation dome over the seedling tray and keep it under T5 fluorescent lighting or in a greenhouse lighting environment. Direct sunlight or high HID lights may be too intense for seedlings. Viagrow heat mats are MET approved and extreme temp tested. This heated gardening mat measures 20.5 in. x 8.5 in.