Yes you can but starting seedlings with a 400 is not the best way....too hot for the little seedlings, youll have a constant battle trying to keep em from getting fryed...plus theyll stretch like crazy....your best bet is to start them under double 40 watt flourescent bulbs, (10 or 15 bucks at home depot) use the cool white bulbs....you can put them very close to the seedlings without fear of frying them this way, theyll stretch very little and grow strong (put a small fan gently blowing on them to strenghen their stems) you can use bricks or macaroni boxes at each end to raise the light every day or two....after three wks theyll be ready for the 400 full on....(make sure the room is at least 80 degrees to start them) hope this helped...