Hey guys.
So I have a 1000w metal halide and will be growing 4 autos in 5 gal fabric planters. I need to know how high off the plants the light should be during seedling, veg, and flower stages. Thanks in advance guys, this is my 1st post but have been reading alot and you guys seem like a solid bunch when it comes to helping out us newbies.
PPFD (the spectrum of light that the plants see) is relevant here. Though PPFD might not mean anything to you, the relative comparison for the various growth stages are useful:
Seedling stage: 300 PPFD
Veg stage: 600 PPFD
Flowering stage: 800 PPFD
Some MH growers will probably come along and help, but in the meantime the most important rule is to not expose your young plants to heat from the light. If you can feel heat on the back of your hand when it is held plant high, then the light is too close.
I let the plant tell me how much light she wants when young. If nodes are spaced too far apart, then the light is too far away. If the nodes are spaced too closely, then the plant is getting too much light.
Start at 3 ft away and adjust accordingly. Looks for signs of stretch between leaf nodes. If too widely spaced lower a bit further.
When you setup a mh/hps you wanna feel the surface it’s going to cover for radiant heat. Your hand shouldn’t be uncomfortable to leave there