All About Fimming Autoflowering Cannabis Plants

Fimming as a plant training technique, how it is done and its benefits, difference between fimming and topping, as well as our top tips.
20 April 2020
5 min read
All About Fimming Autoflowering Cannabis Plants

  • 1. What is fimming?
  • 1. a. What to remember
  • 2. How is it done?
  • 3. The difference between fimming and topping cannabis plants
  • 4. When to perform fimming on autos
  • 4. a. The benefits associated
  • 5. Top tips on fimming autoflowering plants
  • 6. In conclusion

Applying plant training techniques to certain cultivars, can have a massive effect on the outcome of the plant appearance. Allowing a grower to manipulate the growth structure, the shape of the canopy, plant height, and final yields. In this article we explain all about fimming, how it works, the benefits associated, including our top tips.

1. What Is Fimming?

A technique that was essentially created by accident as a failed attempt at topping Cannabis plants, fimming describes the removal of 70% of the crown growth tip. The result is that the energy that would have been used to promote apical dominance is temporarily slowed down, causing a shift in growth energy to the rest of the plants.

What is fimming?


Once the crown growth top has been cut away with 30% of the shoot remaining, it will take around 5-7 days before the crown shoot grows back as normal displaying apical dominance. During this time is when the remaining growth will benefit.

What To Remember

•  Fimming temporarily slows down vertical growth.

•  Energy is used for the rest of the plants as the top shoot recovers.

•  The appearance will become bushy and more stocky.

•  Removing 70-80% of the growth tip is perfect.

•  Plants will take 5-7 days before growing back as normal.

2. How Is It Done?

The art of fimming is very easy to do and should be performed using a pair of clean sterile scissors. By cutting horizontally across the cross-growth tip, and ensuring a sharp and smooth cut the technique is basically performed. If you decide to apply this technique to the main central tip, or the side branches also depending on which cultivar you are growing.

The Difference Between Fimming and Topping Cannabis Plants

Topping is performed on a plant during the vegetative stage, with the idea of totally removing the top growth top, exposing two small-sized axillary growth shoots. The plants will respond by sending all of the primary energy into these two shoots, dramatically reducing the height and width of the canopy. Topping also prevents vertical apical dominance, allowing for the side branches to be grown at the same height as the main cola.

Difference between fimming and topping your plant

Fimming, on the other hand, is done with the intent of slowing down the vertical growth of Cannabis plants. The 5-7 day window as the top shoot restores itself back to normal growth allows the rest of the plant to grow causing a much more stocky and compact appearance.

3. When To Perform Fimming on Autos

It is very important that before you apply this plant training technique, you are well familiar with the cultivar and how well it reacts to plant training. Thanks to the diversity found in autoflowering Cannabis genetics indica dominant strains will prefer one style of growing, hybrids another and sativas their own also.

Fimming is used to not only bulk up plants, allowing the lower buds to become as fat as the top ones, it also allows a grower to reduce the plant height. Sativa dominant autoflowering hybrids such as Orange Sherbet Auto that can grow as tall as 150cm are well suited for L.S.T. and fimming, however, a strain such as Zkittlez Auto will finish between 70-90cm so do not need reducing in height.

Orange Sherbet Auto
Orange Sherbet Auto
Sativa 70%/Indica 30%
Orange Sherbet Auto
9 – 10 weeks
500 – 650 gr/m2
110 – 150 cm
Up to 24%
< 1%
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The window to perform fimming should be done early on if the intention is to reduce plant height. If you are working with medium-sized plants, then applying fimming may have negative effects and cause the plants to grow very small. Once autoflowering plants have passed the 3rd week of their life cycle, it is best to avoid any type of plant training, unless you are tying down a tall-growing cultivar for the sake of the height of the grow space. 

The Benefits Associated

•  Plant will grow with a bushy and compact appearance.

•  The final height of the plant will be reduced.

•  Energy is evenly distributed to the rest of the plant.

•  Fimming is easy to perform and only requires a pair of scissors.

4. Top Tips On Fimming Autoflowering Plants

1. Make sure that you do not cut more than 80% of the top shoot off, as this can end up causing the plants to top themselves, which is the opposite desired effect.

2. Use a clean, sharp, and sterile pair of scissors when making your cut across the crown shoot. Spray the plants afterwards to keep everything clean and contaminant free.

3. Before you start fimming, do everything you can to learn about the strain and make sure that the plants will react well. Not all cultivars require fimming so do your research.


How to perform fimming and what to avoid?

4. Never perform this technique once buds have started to form. Not only can this stress the plants, but it can also interrupt the hormone development as the plant converts itself into flowering mode.

5. For the more experienced grower, applying other plant training techniques such as L.S.T, super-cropping and pruning will all have positive effects on the overall outcome of your harvest.

5. In Conclusion

On the basis that you can apply the right technique at the ideal time, then you will see a big difference in the outcome of your autoflowering plants. Do not find out the hard way in which cultivars don't work well with certain training methods and do your research before getting hands-on with your ladies.

20 April 2020