Sometimes adding warmth to seeds as they germinate will help the process along. And this is task is fairly easy thanks to some creativity and Christmas rope lights! From Vegetable Gardener,
In building the mat, the rope light weaves around long thin strips of wood, and both are attached to a ‘plank’ of plywood. The gaps between the wood strips serve to help with airflow. The rope light will only emit a certain amount of heat – not enough to burn the wood. Since it’s thinner than the wood strips, the rope light doesn’t come in contact with the seed trays. Since the rope light is insulated for outdoor use, it’s protected from water.