I have a 250w hps light and i am doing a scrog grow. I was just wondering how close i can put my light to the plants during veging and during flowering without harming them.
i would say between 14" and 18". it just really depends on how close you can get it without buring the tops...if you stick you hand between the space of the light and your plant tops and your hand feels uncomfortably warm it probably is for the plants too
i wouldnt worry to much i had my 400W HPS about 6-12 inches away from the top of one bud and it didnt burn it and i just have a 6in inline fan on it no ducting
I have my 150W HPS 6 inches from the top of my plants... i also have a box fan on low pointed at them... the room heats up to 82 degrees top... no problems yet