hps for veg

when can you safely start to veg a seedling with hps?

You can veg a seedling with a 1000w hps any time you like. Its a matter of proximity and heat, really. Most people like T5 Flouros or a low wattage HPS. I get seedlings started for a week in a dome and then they go in buckets 30" under a 1000w lamp.

If its too hot, you'll kill them. They'll also dry out more because more light means they transpire more. Keep an eye on that and temps and you'll be fine.

GL.

thanks + rep

Yes the answer is as soon as they break the soil.

You shouldn't have a problem if you just keep the light raised for the first week or until the plant looks healthy and vigorous.