Low Stress Training (LST) is essentially any technique for training your marijuana plants that does not cause them stress in the way that something like topping or pruning could. Like most techniques for improving yields, LST’s main goal is providing as much light exposure to the plants as possible.
LST techniques typically involve pulling the plant in a downward direction so that it grows more laterally and exposed the lower branches to more light (and light intensity). Bud formation will increase on these branches, resulting in a higher yield for each plant and each watt of light. In the end, you get more bud for less bucks.