I am using a string of 15 clear and orange colored christmas lights outside in a clear plastic polyurethane tent for four 5 gallon plastic pails sitting on top of a wood pallet lol... although this is likely not your intention to grow them outdoors it works well for me and is a measure to deal with the cooler outdoor temperatures which came and went in late august and half of september and will be returning again next week including the possibility of frost . We've had two frost days already since the last week of august but yeah it works and is very decorative at night . The bulbs are mainly for added warmth . My bell peppers are half to fully grown so I didn't want to end the season without at least some peppers .