The invention concerns a method of developing tree seedlings, comprising placing seeds on a surface of a growing medium in a container providing air pruning the seedling roots at a depth of 7.62 cm to achieve an improved root mass, wherein the growing medium comprises, by weight: 40% composted rice hulls, 40% pine bark and 20% sand, or 35% composted rice hulls, 35% pine bark, 20% sand and 10% manure; germinating the seeds on the surface of the growing medium to obtain the seedlings; and subjecting the seedlings to air root pruning by growing the seedlings in a bottomless container of about 3 inches deep, and a second air root pruning by growing the seedlings in a bottomless container of about 7.62 cm deep. Furthermore, the invention also concerns a method of developing tree seedlings, comprising the steps of selecting seeds based on seed weight; combining, by weight: 40% composted rice hulls, 40% pine bark and 20% sand, or 35% composted rice hulls, 35% pine bark, 20% sand and 10% manure to obtain a growing me
