Maybe you should put a thermometer on it to check the temp. Mine stays between 25 and 35 C. and the peppers are doing great. If needed you can always put layers of newspapers between the heating pad and the tray. Pretty soon I will put the pepper plants in the pots they will stay in untill planting time in the greenhouse. I plan to wean them slowely from the warmth and make sure the soil in the greenhouse has been warmed up in May sometime.
