DISCLAIMER: Everything taught and sold by BudTrainer® is to be used strictly for legal purposes. We condemn the production of illegal substances and it is your duty to ensure that you are complying with the law. The words "hemp", "cannabis", "weed", and "marijuana" are used interchangeably to refer to the same plant (legal hemp with less than 0.3% THC) for the purposes of this lesson.

Did you know that nearly 100% of commercial cannabis producers defoliate and prune their cannabis plants? They wouldn’t be doing it if it wasn’t increasing their yields. In fact, if left unpruned, your plant can attract mold and bugs such as spider mites, thrips, and aphids. But if you defoliate and prune it properly it will yield bigger buds, more trichomes, and an overall larger yield (with no pests). So let’s get to work.

When: week 5+ of the vegetative stage

Stage 1 of defoliation and pruning is meant to set up a strong canopy structure when your plant is young. By removing old and shaded leaves, and removing small branches, your plant transfers its energy toward the stronger branches and leaves left behind, thus promoting a much stronger base for your plant.

Growing Outdoors?

Stage 1 can be repeated every 2 weeks when growing outdoors.

Growing Autoflowers?

Skip Stage 1 if you are growing autoflowers, as they only get 4 to 5  weeks of vegetative stage time.

When: 3 to 4 weeks after switching to flower

Stage 2 of the defoliation and pruning process is the most essential stage. Performed after the flowering stretch phase, stage 2 is where you get to “clean up” the small and shaded leaves, but also all small bud sites that would otherwise form larfy, popcorn bud. You will leave behind only bud sites that can form big buds.

Growing Outdoors?

The process is exactly the same, but since you can’t know exactly when marijuana plants switch to flower, wait to defoliate until your plant has stopped stretching, and started forming bud crowns.

Growing Autoflowers?

Instead of performing Stage 2 in one day, prune and defoliate on a daily basis, only removing 3 to 5 leaves or branches in order to avoid stress.

When: 1 week prior to harvest day, or on harvest day itself

Performed one week before harvesting or on harvest day, Stage 3 is where you remove all fan leaves that don’t have trichome heads attached to them. This not only makes it easier to trim your buds later on, but it also helps expose the lower buds to more light for that last week of flowering, thus helping them reach the same maturity as the top ones.

Whether you are growing autoflowers or outdoors, Stage 3 is always the same.

This part is easy - start with the largest fan leaves at the lower part of your canopy, and as you go up, remove ALL of them. If your fan leaves don’t have any trichomes on the leaf itself of the leaf stem, you can throw them out.

However, if your fan leaves are covered in trichomes, you can keep them aside for making hashish or extracting.

While you can do the pre-harvest defoliation by hand, cannabis leaves tend to pull skin strings from your main stalk as you remove them like this. This can damage your lower buds, which is why we recommend using scissors to execute all of Stage 3. 

In one week your plant will be more than ready for harvesting, and all you will have to do is chop it. Your lower buds will have been exposed to more light and thus reached maturity, and the amount of trimming left for you to do is minimal.

1. Light Absorption

One of the main purposes leaves serve is that of catching light, just like solar panels. The more exposure to light they have the more photosynthesis they will be able to contribute to the plant, and the bigger the plant will get. Conversely, if leaves are covered or shaded, they will not be able to photosynthesize. It would be the same as putting one solar panel on top of another - the bottom panel won’t catch light. This is why it is important to prune leaves and branches that are shaded by 2 or more other leaves on top of them, or that are touching one another.

2. Transpiration

Transpiration is the process by which water vapor and oxygen leave the plant through the stomata - these tiny little openings under the leaves. At the same time this happens, CO2 enters the leaf from the air, thus allowing the photosynthesis process to happen.

In fact, 95-99% of all the water that plants consume through the roots go back out into the air through the leaves while only 1%-5% stays in the plant and gets converted into sugars. This means that if your plant consumes 1 liter of water per day, it is "vaporizing" around 950-990 ml back into the air. So why do plants waste so much water? 

Well, it's not really a waste. Something else that happens while all of this water comes up from the roots is that the stems, leaves, and flowers take up all of the nutrients in it. So via transpiration, plants are pulling water from the ground, filtering out the nutrients and a little bit of that water for photosynthesis, and evaporating the rest of the water into the air.

This is why it is so important to prune everything that is blocking airflow within your plant, otherwise the humid air can never be carried away and exchanged for dry air full of CO2 again.

3. Nutrient storage

Another purpose that leaves serve is storing the nutrients they just absorbed from the water, so that they can use them later. Nutrients like N, P, K, and Mg are mobile, meaning that your plant can remobilize them from the old leaves to the new ones if they are suffering deficiencies. For example, when the leaves at the bottom of your plant start to go yellow, they are simply "donating" their stored Nitrogen to the new leaves, shoots, and flowers at the top.

That’s why having a certain amount of green and healthy leaves is always important - it helps your plant remobilize those stored nutrients to its most vital parts. If you strip your plant naked like some folks do, you leave no buffer for it to mitigate nutrient deficiencies.