i want to grow 5 plants but my grow space is pretty small... how much room is need between the top of the pot and the lights???
Think of four spaces needed for height: 1) from the floor to the top of the soil 2) from the top of the soil to the top of the plant 3) airspace between the top of the plant and the bulb 4) hanging space for the light So you are talking about #2 and #3. With LST you can keep a plant under 18" at maturity (height for #2). Height for #3 depends on the type of light you use, wattage, temps, etc. For fluoros and CFLs you need only a couple of inches, but for HID you most likely will need in the range of 6-18". My 250w HPS is about 8" above the plant tops, so a total of about 2 feet from soil top to bulb.
I'm using a small (micro) grow and plan to LST, if my babies make it! (see my other thread about using the wrong soil - (*idiot!*)) It looks like this... I hope I'll have enough space once I crank up the light to the top...? The dimensions are W 60cm x H 60cm x L 80cm