LST is low stem training.

Like the name implies, the main stem of the MJ plant is grown very close to the ground, much like a vine would grow.

Evey new node or so is anchored to the ground...thus the plant grows super low and only the secondary growths, which are your main bud sites grow tall...most other foilage is kept low to the ground.

Thus you can grow your plant essentially, sideways. This is excellent for grow spaces that have height issues.