As noted in most posts, keeping the root system at a reasonably warm temperature is critical to vigorous growth. For my indoor veg plants I've been growing in 3 gallon pots that fit perfectly into 5 gallon utility buckets. The three gallon pts have lips that hold the pot in the upper area of the 5 gallon pot, leaving a good two gallons of space below the rooted pot. This not only keeps the raised root system warm, but because the 5 gallon bucket catches the run-off, a humid environment below the roots is created. I even recycle the run-off water/nutes back into each three gallon pot. My flowering plants are then placed in raised beds, 3' x 5' boxes built on a platform made of a shipping palatte with wheels mounted all around. More about the raised bed system can be learned by reading some of the information put together by Soma -- his book is worth a quick read -- "Organic Marijuana - Soma Style."