Essentially, air-pruning is a technique that stops root growth extending beyond its growing media by exposing the roots to relatively dry air (as opposes to getting bound up and wrapping around each other like in a plastic pot).. the roots will grow through a smart pot and out the side of the fabric pot, reach air and then stop growing. These primary roots that are air exposed have nowhere to grow The plant will stimulate an abundance of secondary roots to branch out. These secondary roots will then spread through the medium until they get air-pruned and then stimulate more root growth. The overall effect of this growth and pruning cycle will create a plant with a well developed root system. This causes an explosion of plant growth. I myself am experimenting with Smartpots right now. I have a friend that says it is all he will ever use from now on. I also hear Air-pots work well.