How close does a 100w MH need to be to the plants?

If i use a single hundred watt Metal Halide bulb for vegging how close to the plants should it be? The space is a book shelf i have mcguyverd to a grow box. 2.5-3feet wide and about 4-5 feet tall.

i always go by the hand method..put ur hand by the tops of the plants..if u hand feels discomfort..so will ur plants!!how big r ur plants also?id go atleast 6 in.away.

they didnt sprout yet, i have 2 grows going. this is the latest. using all cfls, but ive been considering throwing an affordable MH for vegging in and a HPS flowering both hundred watt, with the addition of a couple cfls i should get a good grow going.

rockbud said:

i always go by the hand method..put ur hand by the tops of the plants..if u hand feels discomfort..so will ur plants!!how big r ur plants also?id go atleast 6 in.away.

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^^^^^^that!

I didn't know they weren't sproted yet..sorry!!u probably wanna keep them a lot farther then that!!I have a 4oow hps..I keep them abot 8 inches for the plants..and mine do great..to the guys who said f##k that..u didn't give any help..so..u got better advise??