By: Simon
Defoliation means: taking leaves away. But a plant needs leaves to catch the energy of the sun. So why would you take leaves away?
Here's the deal:
Defoliation is one of the most debated topics in cannabis growing. Done wrong, it stunts your plants. Done right—at the perfect moment—it can improve airflow, prevent mold, and let light reach buds that would otherwise stay small. In this guide I explain exactly when and how to defoliate.
Table of Contents
Outdoor vs Indoor: The Key Difference
Plants need leaves and if you grow outside under the sun then it is best to not take leaves away at all.
Indoors is different. Lights are never as strong as the sun. More distance from the lights means less strong light. Some plants are very bushy with many leaves (indica type). Other plants have very big leaves (our 'Serious Kush' is a plant with enormous (fan)leaves.)
Key Difference: Outdoors, the sun is powerful enough to penetrate through leaf canopies—don't remove leaves. Indoors, artificial lights are far weaker and every shaded bud is a wasted bud.
Why Defoliate? Light Penetration and Airflow
The problem is that many leaves or very big (fan)leaves can give shade to buds under the leaves. Outdoors this is no problem because the sun is very strong. Buds under leaves will receive enough light from the sun anyway.
But indoors big leaves, or many leaves, can be a problem. This means: indoors you can take leaves away. One reason to remove leaves is if they shade buds under them. Another reason is to improve air flow between and under very bushy plants.
Does Defoliation Cause Hermaphrodites?
Some people worry about this: 'Do the plants tend to hermaphrodite when defoliating?' Short answer: Serious plants do not go hermie when you take leaves away.
Simon's Reassurance: This is a common fear, but unfounded with stable genetics. Our plants are strongly selected against hermaphrodite tendencies. Removing leaves does NOT trigger male flowers in healthy, well-bred plants.
Defoliation During Veg: Be Careful
When to remove leaves? My advice is to remove few leaves before flowering (still in veg.) You can remove the odd big leaf in veg. Removing a few leaves will not make much difference. But try to wait because plants will respond with growing more leaves the more leave you take away. This means you have to continue to remove leaves. This will again stimulate the plant to grow more leaves, etc. etc.
If you remove a lot of leaves during veg. then a lot of energy of the plant goes into growing more and bigger leaves: not what you want.
Simon's Warning: Removing many leaves during veg triggers a vicious cycle: the plant grows MORE leaves to compensate, you remove those, it grows even more. All that energy goes into leaf production instead of building the structure you need for flowering.
The Perfect Moment: 3 Weeks Into Flower
The best moment to really take leaves away is after the start of flowering. The best moment is when they are 3 weeks into flower. Not sooner and not later.
After 3 weeks of flowering the plants do not respond anymore with growing more leaves. Thats why its the best moment. Now you can take away as many leaves as you like.
Simon's #1 Defoliation Rule: Wait until exactly 3 weeks into flowering. At this point, plants stop producing new leaves in response to removal. This is the golden window—you can defoliate freely without triggering unwanted regrowth.
How Much to Remove: Conservative vs Aggressive
Some growers remove all the bigger leaves, only leaving the buds. This will lower the humidity in the room and drastically lower changes on mildew and fungus. The yield will for sure be less. But its surprising to see how well the buds can grow with no leaves at all.
Trade-off: Aggressive defoliation reduces yield but dramatically lowers mold risk. If you're in a humid environment or growing dense indica buds, the trade-off may be worth it. In dry climates, a lighter touch is usually better.
Lollipopping: Cleaning the Bottom 15cm
The choice is yours, do you remove a lot of leaves, or just the biggest leaves plus the lowest growth at the plant? We clean the lowest 15 cm of all plants. Leaves and side branches: all growth at the lowest part of the stem. This ensures air flow below the canopy and lowers changes on fungus.
Simon's Standard Practice: At minimum, always clean the bottom 15cm of every plant—remove all leaves and small side branches. This creates airflow under the canopy and is the single easiest thing you can do to prevent fungus problems. We do this with every grow.