What is Fimming, Pinching, and Topping Cannabis Plants?

Topping your cannabis plants when they’re young is the easiest way to increase their overall yield!

A topped Cannabis Plant

The Importance of Topping Cannabis Plants

Topping is a crucial process when it comes to growing healthy and strong cannabis plants.

Topping cannabis plants is a high-stress training method for producing larger canopies and greater yields. When done correctly topping allows even and “bushy” canopy growth which allows more light to reach all areas of the plant.

Growers who are seeking to increase their yields and quality of the cannabis produced should consider “topping”, or pruning the canopy, as a way to enhance crops.

What Are The Benefits of Topping?

If left alone to grow without interference, cannabis plants will grow tall and skinny much like a Christmas tree. The plants will have one main stem, or cola, which asserts apical dominance and takes up the majority of the light and nutrients. Cannabis plants can be retrained to have horizontal apical dominance with multiple colas if they are topped properly.

After cannabis plants are topped they will take on a “bushy” growth pattern which produces an even canopy. This type of growing allows more light to reach multiple colas, which will, in turn, produce larger yields.

Topping is also a great technique for growers with limited height in their grow space. Topping cannabis plants keeps the plants from growing tall and skinny and keeps them shorter and bushy, maximizing the footprint of the growing area.

Pinched Node Cannabis plant with 3 branches

This plant was topped at the beginning of the vegetative phase. It now has 3 colas or top branches.

Topping is different from pruning plants in that it removes the apical node of the plant and promotes the growth of the lower lateral branches. Pruning involves removing the lower branches to send more energy to the apical crown of the plant but does not alter the apical distribution.

What Are Auxins?

Auxins are the hormones responsible for apical dominance in cannabis plants. Auxins are located in the main cola at the top of the plant and control the way the plant grows. When a plant is “topped” it redistributes the auxins to lateral branches and changes the apical dominance of the plant. This allows the lateral branches of the plant to grow with horizontal distribution and have a larger canopy.

When apical dominance is broken during topping, lateral branches will begin to develop and grow similarly to the main cola of the plant, producing a bushy shape rather than a Christmas tree shape. This is called apical redistribution and is a response to the redistribution of hormones throughout the plant

How To Top Cannabis Plants

Topping cannabis plants should be performed early in the vegetative growth cycle. As topping is a high-stress training technique it shocks the plant, and if topping is performed too early it will cause poor root development. On the other hand, if topping is performed too late in the growth cycle the plant will still prioritize vertical apical development.

Topping should be performed when four to six nodes are visible and plants should be “topped” at the fourth or fifth node. This will allow lateral branches to grow to the height of the main stem and create a bushy plant. Topping can also be performed multiple times to achieve a bushier plant with multiple colas. Nodes are the spot where new branches come off the main stem of the plant and where flower formation occurs. In order to “top” the plant, the new growth must be removed to allow for the formation of two new branches in its place.

If topping is performed multiple times it is important to allow at least a week between toppings for the plant to recover. Topping stresses the plant for several days and slows growth, however the plant will recover and begin to produce new growth once it has redistributed the growth hormones.

It is crucial to have clean equipment when performing topping, so make sure to sanitize clippers before beginning. This will prevent contamination of the plant.

Topping cannabis with line to indicate fimming mark

These are the tops of two cannabis plants. These plants will start growing two new tops after it recovers.
The red line shows how much should be cut if you want to FIM your plants instead.

What Is Fimming?

Fimming is similar to topping, as it is a high stress training method for growing cannabis plants. Fimming involves pinching off three quarters of the new growth at the top of the plant rather than removing new growth entirely. This causes more colas and main branches to form. Much like topping this will cause the lower branches to receive more plant energy for growth and create an even canopy. Fimming differs slightly from topping in that it has the ability to create 4 to 8 new branches, as opposed to topping which only doubles the amount of growth that is removed. Therefore, if you top a cannabis plant once, two new branches will form. If you FIM the top of a plant, multiple new branches will form.

Cannabis Is Resilient

Many growers are afraid to remove part of their cannabis plant for fear of it hindering growth. It is important to remember that cannabis is a resilient plant which will recover from topping in a few days.

Topping is a healthy practice for plants as it increases yield and produces larger colas.

What Happens if I Don’t Top My Cannabis Plants?

If cannabis plants are grown in their natural state, and topping techniques are not used, they will grow just fine. Cannabis plants adapt to their environment and will grow tall and thin like a Christmas tree with one main apical cola and numerous smaller branches which produce small, fluffy flowers.
The downside to this natural growing method is that it limits the yield of the plant. The one main cola utilizes 90% of the light, nutrients and growth hormones and there are very few resources for the smaller, lower branches. This results in small flowers with lower trichome production. When plants are topped, apical redistribution occurs and the plant will have multiple colas which receive full light and nutrients. This allows each branch of the cannabis plant to produce bigger, denser flowers.

“Pinching The Node”

Pinching the node, in the context of cannabis cultivation, is essentially the same as the technique known as fimming. Both methods involve the deliberate removal of part of the cannabis plant’s new growth but to different extents.
In this case you pinch off part of the top node (new growth) with your fingers instead of using scissors.

Can You Top Autoflowers?

Topping autoflower cannabis is possible, but it requires careful consideration due to the plant’s rapid growth cycle. Autoflowers move from the vegetative to the flowering stage without the need to alter light cycles, typically within a few short weeks. Therefore, if topping is on the agenda, a grower must act swiftly and precisely. The optimum time to top is when the autoflower has developed between three to five nodes, which is usually early in its life cycle.

The window for topping autoflowers is narrow because these plants need ample time to recover before they begin flowering. Any stress, such as that from improper topping, can potentially hinder their growth and reduce overall yields.

Tips for Topping Cannabis

  • Use a clean pair of pruning scissors for cutting the new growth. The plant will be stressed after topping and more susceptible to infection.
  • Top your plants right after transplanting. This will give your plants a shorter stress recovery period.

If you want to learn even more about growing good cannabis, we offer a free 40+ page guide full of images.
Now available on Amazon.
Sign up for our newsletter and download the digital copy today!

Beginners guide to cannabis cultivation

This guide will answer many questions about growing cannabis, like the following...

Selecting Seeds
Identify and Correct Problems
Maximize Yield
Much More...

Get a Chance to INSTANTLY WIN a Reefertilizer Nutrient Kit When You Sign Up.



Get a Physical Copy Of Our Grow Guide On Amazon

3 thoughts on “What is Fimming, Pinching, and Topping Cannabis Plants?

Comments are closed.