so hang it like 3 and a half feet from the top of the plants? Also another small side question is there any difference between the effectiveness in putting the seeds in a wet papper towel till they pop then plant them vs just planting them in the dirt and waiting for them to pop on there own?
If done correctly, the seeds started directly in quality potting mix should fare better. Paper towels add more fuss to the germination procedure, if you ask me. Seeds essentially just need moisture and warmth to germinate, and to not be suffocated. Common mistakes include: not watering
thoroughly after planting (pre-moisten mix if very dry), using a sealed dome or similar covering, temperatures too cool, or using an inappropriate mix for seeds. Between 72-82F is ideal for germination. This can be achieved with a hat mat, or lighting.
Fresh, healthy seeds less than a few years old should have no trouble germinating in potting mix, no soaking or paper towels required. A high humidity environment isn't required for seed\seedlings, and can lead to damping off which will kill the seedling. Over a dozen different pathogens can cause damping off, some like it cool and humid while others like it warm and humid. Cannabis isn't an aquatic plant and seeds don't require so much wetness anyways. Furthermore, the seed embryo, tap root and all of the root cells require oxygen: respire aerobically. Water itself doesn't hold oxygen very well.
As for the lighting, how far you keep it depends on a couple things like what the ambient temperature is already, and reflector type\how the bulb is cooled. If it is cool enough you can put the bulb closer, and I would suggest it, at least once they sprout. Many prefer to germinate seeds under different lighting, like T5's or similar fluorescent fixtures (or LEDs). These provide plenty of light for seedlings, and usually just get a little 'warm' and not HOT like HID lamps. The benefit here is you can keep the tubes within several inches of the sprouts without risking any damage. The growing seedling receives plenty of light and grows nice and compact (shorter spaces between nodes). Seedlings have a tendency to stretch if they don't get enough light early on.
Oh yeah, another thing is consider the container size you are using and make sure they aren't too small, esp. if you want to use the 400 watt lamp. Use an oscillating fan as opposed to keeping a fan blowing air on the pots constantly. Smaller containers will dry out way faster under that light, and a fan will accelerate this...
