My plants are four and a half weeks into flowering and the buds are coming on nicely. They are under a 400 watt hps about 18 inches away from the light. What i wanted to know was, is this the optimum distance to get nice fat buds or does my lamp need to be a bit closer? I have 6 plants under the lamp, so if it is too close to them the outside plants might not get enough light. Any help would b e appreciated as this is my first grow!
18 inches sojunds about ok. But to get maximum lighting, heres the method I use. Put your hand right infront of ur plant. If the heat from the light is uncomfortable on your hand, it will be uncomfortable on your hand. Adjust untill it feels just about right, not hot but still warm on your hand, somthing you could stand sitting in for 12 hours a day.
If you have a fan blowing between the light and the top of your plants and sufficient fresh air flow, you can get as low as 14". The 'hand-check' is also a good method. Peace.
in addition to what has been said, i have read that a good rule of thumb is 4" per 100 watts of lights...so if you have a 400 watt hps/mh, you should have it around 16" from the plant. hope it helps.