imo..yes , to intense for seedlings ( unless you are experienced and can read them)... you will either heat stress if too close or they will stretch too much if lights are to far...i use flurs/or cfl's for seedlings, they can be much closer and we can control the stretch so they are not so lanky, then once they are growing and get their true leaves, 3-5 spear leaves, then they can go under the Hid. peacehello i have got some seeds and im watin for them to crack and i just wanted to no once they do crack is a 600 watt light to strong to put them under ????