Defoliation
Definition: Defoliation is the deliberate removal of cannabis fan leaves to open the canopy, let light reach lower bud sites, and improve airflow through the plant. Growers usually defoliate in stages during late veg and early flower, taking only a portion of the leaves each time so the plant keeps enough foliage to photosynthesize.
How Defoliation works
Fan leaves are the plant’s solar panels and its nutrient pantry. They capture light, and they store mobile nutrients like nitrogen and magnesium that the plant draws on during flower. That’s why defoliation is about selective removal, not stripping.
Which leaves to take
- Large leaves completely shading a bud site below them.
- Leaves pointing into the center of the plant where air barely moves.
- Leaves overlapping or touching neighboring plants.
- Low, yellowing leaves that sit in deep shade and contribute little.
Common timing
Many indoor growers do a light pass just before switching to 12/12, then a second pass around day 21 of flower, after the stretch slows. A good cap is 20 to 30 percent of the foliage per session, with at least a week between passes.
Why it matters
Dense, leafy canopies trap humid air. Opening them up helps keep relative humidity even around the buds, which lowers the risk of bud rot and powdery mildew in late flower. It also lets more light reach mid-level bud sites, so they finish denser.
When to hold back
Skip or minimize defoliation on stressed or deficient plants, on autoflowers late in their cycle, and outdoors in hot, sunny climates where leaves shade buds from heat. If a plant looks hungry or pale, keep its leaves; it needs them.