Hey this will be my second grow, first one with my new HPS light i was just wondering how long should i let my plant grow before i can turn on my light and it be safe and not burn my little seedling?
if its the only lamp you have, turn it on as soon as... keep it in a propagator/humidity dome or clear tupperware container so that it wont dry out quickly, keep the lamp high to begin with, then gradually lower it.
I have had no problems even using 1000watt hps to germinate seeds and grow seedlings before. Keeping it maybe 5 feet away to start, then lowering it down to try to avoid stretching. I don't recommend it, nor do I think its a good way. And I am on my umm....100th grow Actually it might really be my 100th, 17 years times 6 ....HOLY SHIT
i use a 250watt cfl to propergate for about a week then swith to my MH/HPS. best light to youse for vegging is a MH for the UV rays an blue spectrum out out but a HPS will surfice if that all you have
You can turn it on anytime, just make sure that it's far enough away not to burn or bleach your plants.