Trimming Cannabis Fan Leaves

Trimming Cannabis Fan Leaves: When Should You Be Schwazzing?


When you’re growing cannabis, tiny details can make a big difference on your yield and the quality of your product. One technique that is somewhat controversial and that requires extreme attention is Schwazzing, or trimming cannabis fan leaves.

I’ll share my experience in commercial and home cultivation to guide you through the labyrinth of extreme defoliation. Tag along and use the comment section at the bottom if you have any questions!

Trimming Cannabis Fan Leaves
Clean, sharp pair of pruning shears for schwazzing

The Science Behind Trimming Cannabis Fan Leaves

Cannabis plants, like other photosynthesizing organisms, rely on their leaves for energy production through photosynthesis. The fan leaves, with their characteristic serrated appearance, are the primary workhorses of this process in cannabis plants. They house a dense network of cells that convert sunlight into sugars, powering the plant’s growth and development.

But, as they say, there can be too much of a good thing. Oversized fan leaves or an overly dense foliage can create a microclimate conducive to pests and disease.

The excess in leaves also shade the lower branches, preventing them from receiving optimal light for bud production. Therefore, strategic trimming of these leaves can boost overall plant health and yield.

But understanding the parts of the leaf is really important for you to do proper trimming. I don’t want you to take my work blindly, so let’s first take some time to better understand the components of fan leaves.

The petiole, the stalk attaching the leaf to the stem, is your cut-off point. The leaf itself has two main surfaces — the ventral (lower) surface and the dorsal (upper) surface, responsible for various physiological processes. The apex is the pointy tip of the leaf – it’s there for more than just giving cannabis its iconic look!

When you perform schwazzing, you remove these leaves so it’s critical that you do it at the right time and in the right way so you don’t injure the plant. More on that below.  

How And When To Remove Cannabis Fan Leaves

The timing of trimming fan leaves is a careful balance. During the vegetative stage, you should be conservative, removing fan leaves during veg should only be done when they are yellowing, dying, or shading significant portions of the plant. Pruning too heavily at this stage can stunt growth. Remember that the veg stage should prepare the pant for flower so it needs to be strong and healthy as it grows out to the optimal size for your reservoir.

As the plant enters the flowering stage, more aggressive defoliation can be considered. However, deciding when to remove fan leaves during flowering is a nuanced process. During the early flowering phase (1-3 weeks), you can prune fan leaves that are overshadowing bud sites or impeding airflow. Mid-flowering (weeks 4-6) is typically a no-trim zone – the plant needs its energy for bud production. In the final weeks, removing fan leaves during flowering is acceptable, particularly if they are dying or blocking light.

So let’s take a look at how to do complete schwazzing in a practical setting!

Schwazzing fan leaves
Schwazzing fan leaves one by one

The Schwazzing Technique Explained

Among the various defoliation techniques, schwazzing has gained popularity for its drastic approach and potentially high yields. The schwazzing method involves stripping fan leaves during flower in an aggressive way.

You do the first schwazzing right before switching to the flowering light cycle, and the second schwazzing around day 20 in flower.

  1. Take a clean, sharp pair of pruning shears. Sterilize your cutting tool to prevent introducing disease into the plant.
  2. Start from the bottom and make sure not to injure the plant, remove all fan leaves below the top 2-3 nodes. You should be left with a plant that looks like long sticks with little leaves at the top. Those leaves at the top are important for not completely stopping photosynthesis. It’s going to feel strange the first time and it will put some stress on the plant. Just trust the process!
  3. You can also lollipop the plant and remove unwanted smaller branches that you don’t want your plant to waste energy on
  4. That night you switch to flower (12/12)
  5. On day 20, repeat step 2 but make sure not to injure any sections with flowers.

Schwazzing is not for the faint-hearted or inexperienced so start on one or two plants and get to know your genetics so you don’t make mistakes that impact your entire harvest.

You also want to make sure to run the best possible cannabis nutrients and soil microbes to give your plant all it needs to bounce back after the defoliating.

The Risks Of Extreme Defoliation During Flowering

While there are amazing benefits to heavy defoliation techniques like schwazzing, it’s crucial to be aware of the risks before you get started. Trimming leaves during the flowering stage or cutting off big fan leaves will put your plant under stress, affecting its overall health and production capabilities. Over-trimming can also expose the plant to more light than it can handle, leading to light burn. Good nutrients and controlling the grow room is key!

Other Ways of Defoliation: Schwazzing vs Lollipopping

There are other defoliation techniques to explore as well. Topping a cannabis plant involves cutting the main stem to encourage bushier growth and more colas. Lollipopping is removing all growth at the bottom of the plant to focus energy on the top buds. Mainlining, or manifolding, is an advanced technique of creating a “manifold” of main stems for even growth.

What Happens If You Don’t Remove Fan Leaves?

Not trimming your plant can lead to overcrowding, restricted light penetration, and an increased risk of pests and diseases. On the other hand, the plant might still produce a reasonable yield, especially if it receives ample light and nutrition.

Do Fan Leaves Contain Cannabinoids?

Yes, but in relatively low concentrations compared to buds. They are mostly present on the leaf’s surfaces, in tiny, crystal-like structures known as trichomes. But don’t be tempted to over-trim in hopes of a potent hash – the cannabinoid content is still minor, and the main aim of leaf trimming is to optimize the plant’s energy usage and light exposure.

Proper Nutrition Is Essential For Maximum Defoliating Impact

Defoliation techniques work best when combined with adequate plant nutrition. After trimming, plants need extra energy to heal and grow. Proper nutrient administration, such as nutrients from Organitek, helps the plant recover swiftly. Products like Amplify can be particularly beneficial in ensuring healthy, robust growth post-trimming.


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