1/2-2" away... as close as you can get them.

They don't get hot so, they can even touch them.

Keriann~

I always read that plants should be that close, but I only do so with the smaller lights. My indoor starts seem to grow at a good rate without getting leggy, so there's no harm in increasing the distance to 12" or more under the big light if it's more convenient.

so there's no harm in increasing the distance to 12" or more under the big light if it's more convenient.

Sorry but I would have to disagree strongly with that. There is just too much evidence to the contrary.

As keriann said, the closer the better when using fluorescent shop lights. Now halides or some other form of light is quite different and growing temperatures as well as the amount of lumens provided must be considered too. But the standard recommendation for using shop lights is "close as possible and no more than 2 inches".

Dave

Ditto what Dave said. At 12", the standard shop light simply will not deliver enough lux or foot candles of light to the seedling to keep it from stretching under normal growing conditions. Keep the temps Mike

I have to disagree with keriann. You do not want the lights touching your plants for more than a couple of hours. It will desiccate the leaves. I find that 2-3 inches is about as good as it gets seeing though it is under 2 lights instead of 1 when under dual tube fixtures. Also it's hard to keep temps under 55 when a 90 degree or higher light is on top of you.

Ah yes Taz...

I forget that I have cooler temps and a fan going. Maybe not the best idea the seedlings are in warm temps to begin with.

Good point

Keriann~

With common shop lights my experience was that I found them best as close as possible without touching.

On some I even devised a pulley hoist to lift the lights when I wanted to work with the pants or when the plants got tall enough to touch the fluorescent tubes.