Home Growing Knowledge Topping or FIMing – A comprehensive guide in High Stress Training (HST) for home grown cannabis

Topping or FIMing – A comprehensive guide in High Stress Training (HST) for home grown cannabis

written by CJ Cummings August 16, 2018

Every grower is introduced to plant training early in their career to ensure the foundation built in the vegetative stage is sound during the final days of flowering. High Stress Training (HST) techniques like Topping and FIMing, uses the plant’s hormonal response to stimulate cola count and boost overall harvesting yields.

Topping is the process of cutting the stem above the node preventing vertical growth while FIMing (F**k, I Missed!) is cutting the top growth above the emerging new node. When we TOP or FIM, it triggers chemical signals to the lower nodes telling them to boost growth. This switch in apical dominance – which cola is the main cola – creating a bushier and wider plant.

HST causes chemical reactions to occur within the plant itself – unlike Low Stress Training (LST). When you perform LST to expose more colas, she bounces back swiftly. The opposite is true for HST, which can slow down growth for a few days.



Topping activates 2 cola nodes to receive the chemical growth hormones within the plant. The cut is usually made above 3 to 4 nodes from the base of the selected stem. Nodes just below the incision will eventually create two dominant colas where the one once existed, This method will dramatically reducing further vertical growth while promoting a bushier structure.


FIMing can be precise. Using trimming shears or surgical scissors, the top growth can be removed while preserving the emerging node below. All it takes is patience and a steady hand. (Hold your breath, then cut) The sliced emerging leaves will continue to grow into stubby fan leaves. This trauma slows down growth of the emerging node. However, the top and lower half of the plant will continue to boost in horizontal growth over time but will not reduce the plant's height as it grows. 

So when to TOP or FIM? Which is best for which situation? Well, it varies with each individual grower and their confined grow space.

Micro Grows 

Space buckets, small grow tents, closet grows, or grow boxes – the control over the number of colas is key in keeping a plant within the confinements of it’s chamber. Topping always provides two colas while FIMing provides two colas and possibly the option of three or four. With the firm knowledge that two colas will emerge during Topping, this technique would be the prefered choice for cola control while accepting the extended vegetative time (4 to 6 weeks). FIMing could possibly provide more, however growth is not always even when considering the best means to control cola count.

Medium Grows

Medium grow tents or small grow rooms – FIMing will not only make switching apical dominance easy but having multiple plants in this situation will also save precious time. FIMing in these confinements can be done by pinching off the top with your fingertips, allowing you to move around the plant and adjust canopy height accordingly. Topping can be done as well in medium grows but it cannot be done well with just your fingertips. Small shears are best suited in this situation which will ultimately increase your workload. Strategically planning what not to cut off is another factor while dealing with multiple plants. 

Large Grows

Large grow rooms or outdoor grows – Topping would be best done early in the vegetative stage to control the framework of stems for flowering. The ability to grow trees and extend the vegetative duration, this technique provides control of the overall plant structure before transplanting. Once outdoors – as she swells in height and girth –  FIMing provides the same benefits as grow tents or grow rooms. The combination of both methods is undoubtedly beneficial in these situations.

Each grower has their own comfort level based on their knowledge and experience. While one grower may feel quite comfortable removing the top growths with their fingertips, another may find the control with a pair of shears more favourable. The joy of cultivating is knowing we all have the same foundation and the love of this blessed plant that brings us together into an ever-growing community.

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