As long as you keep that 400Watter a safe distance from the plants, they won't burn up. By the sounds of it they sound quite young still. I would keep that light about 3ft from the top of those plants and a small fan blowing on them, so you don't burn them up., and to stengthen the stem for the weight to come Good luck! Peace
Nochowderforyou Reviewed by Nochowderforyou on . When to put under HPS light? This is my first grow i got 4 plants growing and they are about 9 10 days old, one is kinda lagging behind at 4 days. i was wondering when i could be able to get them under my 400watt HPS light. its a multi-purpose blub which gives off both red and blue spectrum. so far they have had jus normal sunlight. Soz but not able to put pics on cuz its dark n they turned out rather shiite but ill take som pics in the morn! Rating: 5