There are a variety of factors that come into play when growing a huge plant. One of the first being, the longer the plant vegetates for, the bigger the plant, starting indoors earlier helps a lot. As well as a proper soil medium, lots and lots of water, lots of fertilizer, and lots of sunlight. Sativa strains are usually big plants but more commonly grown in more tropical climates. Indica is more of a shorter plant with dense buds. There is a lot of hybrids of indica and sativa, most of the seed banks will mention about a plant size in the description. Some seed banks offer strains that claim to grow to 3 meters. I would just shop around online on some reliable respected seed banks. nirvana-shop and attitude are well known popular seed banks. Hope that helps, peace