Why Defoliate Weed Plants: Guide to Timing and Technique
Defoliation sends light and air into the cannabis canopy. Learn why growers defoliate weed plants, when to do it, how much to remove, and the risks.
How Much to Defoliate Cannabis Leaves
Remove 10% to 20% of fan leaves per session. In flower, remove 20% to 30% at day 21 and day 42. Never remove more than 30% of total leaves at one time. Defoliation above 30% causes shock and yield loss.
cannabis defoliation stress recovery
Vegetative Stage
Remove 10% to 15% of fan leaves every 2 to 3 weeks. Target leaves in the lower third of the plant. These leaves receive less than 100 PPFD. Keep all leaves on the top two nodes.
Flowering Stage
Week 3 of flower: remove 20% to 30% of fan leaves. Week 6: remove another 20%. Do not defoliate after week 7. Sugar leaves on buds stay. Fan leaves on main colas stay.
Which Leaves to Remove
- Leaves that block light to bud sites.
- Leaves touching soil or mulch.
- Yellow leaves and leaves with pest damage.
- Lower third of the plant.
Which Leaves to Keep
- Sugar leaves on flowers.
- Top 2 to 3 sets of fan leaves.
- Leaves on main colas.
Risks of Too Much Defoliation
More than 30% at once causes shock. Growth stops for 3 to 7 days. Yield drops 10% to 20%. Stress can produce hermaphrodites. Defoliation removes stored energy. Leaves make sugar for buds.
Cannabis Defoliation Stress Recovery: How Long It Takes and How to Help
Tools and Method
Use clean scissors. Wipe blades with 70% isopropyl alcohol. Pinch the petiole. Cut at the base. Do not tear. Tearing damages stem tissue.
After Defoliation
Lower humidity to 40% to 50%. Increase airflow. Keep temperature at 75 to 80 F. Wait 2 days before the next session. Check for stress signs: drooping, curling, or slowed growth.