Max height for HPS light in a room?

Using a room instead of a tent that’s 8’ tall. HPS light is rectangular and 7" in height.

If I assume a 100% sativa, Strawberry Cough, may double in height during flowering, and that a 600/750 watt HPS needs 2 feet distance from bottom of light to top of the plants, should I begin the light cycle change at 2.5 feet plant height (floor to top of plant)?


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Yes, 2-2.5 feet would be a good time to start flowering.


I keep my 600 aircooled at 16" but last two weeks i raise a bit to help reduce foxtailing

What watt HPS? As I run my 600 watts alot closer than two feet, more like 15 inches.

The height of the room isn’t the factor, it’s distance to plants. They solved this one years ago by inventing rope hangers or many like me just fasten our lights hard to the ceiling and raise our plants up on buckets to the desired height.


Yes, seems like 18" is best for me with 750 watts HPS.