Need help with distance of light away from plant.

So Im intending on using 70w hps throughout the grow of 2 SoG white widows,my question is,when i germinate the seeds and I get a sprout,I plant it in a pot,how far does the lamp have to be away? also how long.
When I get to the vegetation stage,how far does the lamp have to be away? and when i finally get to flowering,how far does the lamp have to be away then?

When using HPS, the general rule is the closer the better, but if it's too hot for the back of your hand after a couple minutes, it's too hot for the plants.

stonedest said:

When using HPS, the general rule is the closer the better, but if it's too hot for the back of your hand after a couple minutes, it's too hot for the plants.

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Thx for the useful info