Defoliation refers to the agricultural process of strategically removing and eradicating select living green fan leaves from a growing cannabis plant. When performed carefully, defoliation promotes better light exposure and air circulation deeper inside the densely foliated plant canopy by opening it up. However, defoliation exclusively targets only the very largest shade fan leaves specifically, not whole branches or any parts containing flowering buds emerging on them.
The main goals of properly planned defoliation are to increase quality and yields by allowing as much natural or grow light as possible to penetrate fully within improved line-of-sight to the lower buds that would otherwise end up shaded or obscured by the broad overhead canopy once flowering begins in earnest. Increased passive air circulation flowing freely through the plant also significantly decreases problems with unwanted mold, mildew, pests and overly high humidity levels.
Well-executed defoliation should only target the most mature plants with well-established vigorous foliage and avoid excessive stripping that places undue stress on the plants. Finding and maintaining the optimal gentle balance and timing takes experience observing a given strain's responses and recovery closely over multiple growth cycles.