What you could do is point a fan at the bulb. This should lower the heat a little, so you could get it closer. Basically, get it as close as you can, as long as the tops of the plants are at 75F.
LIP Reviewed by LIP on . HPS LAMPS I have a 400 watt hps lamp and wondered what is the ideal distance between the top of the plants to the lamp ? I cannot get my lamp very close to my plants as they curl upwars and i posted this on here and LIP said this was because of the heat. I don't want the plants to stretch so if anyone knows the ideal distance that would be much appreciated. Cheers Bob Rating: 5