when to fim cannabis

Marijuana Pruning: Topping Vs Fimming

Do you dream of long-running, resinous, chunky cannabis colas? Make it a reality in your marijuana garden with high-yield cultivation methods. Topping and Fimming are two proven techniques. Keep reading to find out which one is the best method for you.

  • 1. What is topping cannabis?
  • 1.a. When to top cannabis
  • 1.b. How to top cannabis
  • 1.c. Equipment for topping cannabis
  • 2. What is fimming cannabis?
  • 2.a. When to fim cannabis
  • 2.b How to fim marijuana
  • 3. Limitations of topping and fimming
  • 4. Pruning and training for maximum yield
  • 4.a. Lollipopping
  • 4.b. Scrogging
  • 1. What is topping cannabis?
  • 1.a. When to top cannabis
  • 1.b. How to top cannabis
  • 1.c. Equipment for topping cannabis
  • 2. What is fimming cannabis?
  • 2.a. When to fim cannabis
  • 2.b How to fim marijuana
  • 3. Limitations of topping and fimming
  • 4. Pruning and training for maximum yield
  • 4.a. Lollipopping
  • 4.b. Scrogging


Topping is the process of pruning the growing tip of the main stem of a cannabis plant. This is perhaps the most common HST or high stress training technique applied by both indoor and outdoor growers. Marijuana growing naturally will typically take on a Christmas tree structure; One dominant, main central cola and multiple sets of side branches. All plant parts receiving a share of sunlight at some stage during the day as the sun traverses the sky.

In contrast, indoor cannabis plants receive illumination from a stationary grow lamp positioned above. This makes naturally-shaped cannabis plants inefficient to crop indoors, unless you cultivate in large numbers using the SOG or Sea of Green method. Topping is the method of choice for pro growers to increase yields. It is also favoured by home growers that want to fill out their grow space with a handful of plants, rather than pack in as many as possible.

Removing the terminal bud will encourage the development of two new main colas and promote growth of the lower, secondary branches. The aim is to invert the Christmas tree shape to allow more light penetration. Growth hormone is diffused to all of the shoots once the apical bud’s dominance is removed. Branchy, low-profile plants are more desirable to every grower. Indoors, vertical space is often at a premium and outdoors, bushes are stealthier than tall trees. Topping is a great technique to take control of the cannabis canopy.


Top your plants after they’ve developed between 3–5 nodes, as this is when their roots and stems are strong enough to recover from the stress of the process. Plants typically reach this size after around 30 days of vegetative phase. Be mindful that different varieties grow at different speeds.

Plants can’t handle topping during the seedling stage. If you try topping during this time, you risk killing or stunting your seedlings. Similarly, topping during the flowering phase is sure to cause damage to your precious plants.

Wait about 1–2 weeks before topping new growth. Your plants will require this time to recover from the stress and readjust to the new growth pattern.


To top a plant, make a clean cut to the tip of the main stem using sterile scissors and fully remove the top growth. Be sure to leave about 5cm of space between where you cut and the lateral branches. This will give you slight room for error and help you avoid accidentally severing these important structures.

Instead of forming a solitary central cola, the plant will now grow two separate branches—the main cola will not continue to grow and the two side nodes will take over as colas.

You can repeat this process later on down the line. Eventually, the two branches you just created will be ready to top. This will further divide what was a single terminal flower into four distinct bud sites.

Continue the process until you’re satisfied with your plant’s canopy.


Topping cannabis requires accuracy, precision, and cleanliness. Snipping your plant with a blunt tool can cause the stem to break and it can leave a much larger wound than intended.

Use the sharpest blades you can get your hands on. Office and kitchen scissors work, but they’re not as efficient as tools specifically designed for the job, so consider using pruning scissors. Razor blades are also a good option.

Try out these Curved Trimming Scissors made for taming and topping cannabis plants. The sharp blades and robust handle make them perfect for your needs. Their curved design makes them perfect for pruning deep within canopies and trimming off sugar leaves during harvest. You can also use this handy tool to obtain clean cuttings for cloning.

Top and FIM your plants with accuracy and ease using these Curved Trimming Scissors. The sharp blades slice through cannabis stems without leaving a mess behind—allowing plants to recover swiftly.

Top and FIM your plants with accuracy and ease using these Curved Trimming Scissors. The sharp blades slice through cannabis stems without leaving a mess behind—allowing plants to recover swiftly.


Fimming is another HST technique used to increase yield that is similar to topping, but not quite the same. The objective is still to increase the number of main colas. But instead of doubling down, fimming can give rise to 4+ new top colas. This technique is highly recommended for micro-growers with perhaps just 1-2 plants.

Secondary shoots are juiced with the growth hormone that previously would have been used to develop the main stem. However, most growers report that fimming is slightly less effective at reducing stretching than topping. A fimmed cannabis plant can still grow rather tall, albeit with far more top colas.


Wait until your plant has developed 3–5 nodes before you FIM it. Like with topping, performing the procedure too early will shock the plant and slow down the growth of your seedling. You should only FIM plants during the vegetative phase to allow plants to focus all of their energy on bud production during the flowering stage. If you want to train your plant during this time, try gentle techniques such as low-stress training (LST).


Fimming involves pinching or cutting off around 75% of the tip of a plant. The very word FIM stands for “f*ck I missed”, and hints at how sloppy the technique appears. It looks as though the grower messed up their topping attempt! Looks aside, it’s an extremely simple and effective technique.

Grab the tip of your plant and gently elongate the growth with one hand. Use a pair of clean scissors to snip about 75% of the top. You’ll be left with a small turf of growth that will eventually give life to four colas.


Topping and fimming will prolong the amount of time cannabis plants will need to spend in the 18/6 vegetative growth stage. Expect a 4-6 week vegetative growth phase if you plan on applying these techniques.

Another oft-overlooked and obvious problem with encouraging the formation of multiple fat colas is that marijuana plants tend to become really top heavy. In the absence of a ScrOG, plants may require staking with bamboo for support.


Do you want the heaviest harvest possible? If you do, then you must be prepared to blend a few techniques. Topping or fimming cannabis plants alone is not really going far enough. Go the extra mile for those extra grams. By adding the following two methods to the mix, you might hit upon the recipe for a scale-tipping harvest.


In brief, lollipopping is the removal of fluffy, lower bud sites from cannabis plants. The idea is to focus plant energy on developing big, fat nugs, rather than popcorn buds. Most growers like to strip away lower growth during week 3 of flowering. Pinching off is generally preferred to clipping away with a scissors. ScrOG growers will usually remove all of the lower growth beneath the screen to improve airflow and drive all plant energy to the tops.


All of the above high-yield cannabis cultivation techniques can be further enhanced with a ScrOG or Screen of Green. A ScrOG is the pinnacle of high-performance marijuana growing. By deploying a mesh screen across the grow space, the whole grow-op is tuned for maximum production. Essentially, the grower must bend and fold shoots to fill out as many of the grid squares as possible. This begins in the vegetative stage and continues on until early bloom.

Push your marijuana into maximum overdrive with high yield pruning methods. This one is all about Topping and Fimming cannabis plants.

Fimming Cannabis: Everything You Need To Know

FIM or F*ck I Missed – yes that’s really what this cannabis acronym stands for – is a pruning for yield method. Similar to topping, this technique involves removing a portion of the main stem. As the legend goes, the whole method was invented by accident when a grower botched a topping job.

The objective is to promote multiple main colas and make plants bushier. Fimming might not be the neatest pruning for yield method, but it is proven to be effective. By the end of this grow guide, you will be able to experiment with the FIM method yourself. We recommend topping and fimming at least a couple of plants in the grow op.

When To Fim

As is the case with virtually all pruning and training for high yield methods, it’s best to FIM during vegetative growth. Whenever you clip parts away from your cannabis plants, they will be stressed and will need some time to recover from the pruning. This is the primary reason to prune prior to the onset of flowering.

In the US it’s common for growers to pinch off the tops from infant cannabis plants barely out of the seedling phase. Although this ensures plants will grow like bushes, it needs to be followed by LST and/or a ScrOG. If you have got the hands-on experience in all the above techniques, go for it. But for the novice grower or growers without the time for a lengthy vegetative cycle, this is not ideal.

European cannabis growers prefer to wait until plants are around 30cm tall before applying pruning for yield methods. Allowing plants 3-4 weeks of vegetative growth to get to a decent size and develop means they will recover faster. Fimming can be applied anytime in the vegetative phase. No need to rush. Being patient in the early plant lifecycle can save you time later.

How To Fim

To apply the FIM method couldn’t be easier. You have a choice between pinching and snipping. It all comes down to what is the most comfortable style for the grower. If you prefer to prune with scissors, then stick with your sterile clippers.

It’s best to keep in mind that Fimming originated from an instance of inaccurate plant topping. Fimming is the process of removing approximately 75% of the tip from the main shoot. Pinching off the area between the fingertips allows more room for error and often results in a more successful FIM.

Just make sure to FIM during vegetative growth. Precisely when to FIM is at the grower’s discretion. Take note plants will need about 1 week to recover and for the new growth to develop. Expect an ugly sight in the aftermath. A set of torn leaves if you pinch and a Medusa head of colas are typical.

Topping a cannabis plant neatly with scissors by completely removing the tip from the main shoot gives rise to two new main colas. Fimming usually gives rise to 4 new main colas. These numbers can vary slightly depending on strain and how much of the main stem was removed. Furthermore, the FIM will also encourage the plant to bush out and fill lateral grow space too.

Benefits Of Fimming

Fimming can be even more effective than topping for increasing the yield of cannabis plants. Obviously, 4 main shoots are more than 2. Furthermore, fimming seems to effect the auxin distribution in marijuana even more profoundly than topping. Plants that have been fimmed not only develop a greater number of tops but also branch more abundantly.

Fimming is a very flexible pruning for yield method and can be blended into a mix of other training and pruning techniques for maximum yield. A FIM crop of a handful of cannabis plants combined with a ScrOG can be just as productive as a SOG with 2-3 times the number of plants.

An early applied FIM, as is preferred by US growers, is tremendously effective at transforming plants of any strain into squat branchy bushes. Plus the FIM method can be applied multiple times until the grower is satisfied with the density of the weed bush.

The greatest benefit of the FIM method is that it’s forgiving. Accuracy is not the primary objective. A sloppy Topping can often turn out to be a fantastic multi-cola FIM.

Disadvantages Of Fimming

Fimming is a technique that does not lend itself to Autoflowering cannabis varieties. The stress of pruning the main stem and the associated recovery time will stunt the growth of Autos. On average growers using the FIM method will keep plants in vegetative growth for 4-6 weeks. That’s just too long for an Auto grower to wait.

Later in the bloom phase in the absence of a ScrOG, it can be difficult to keep the grow space orderly. If you decide to FIM as a standalone high yield method, it’s probably best to stake plants for support. All those heavy colas can make marijuana bushes top heavy with bud, but this is a good kind of problem.

Some high yield cannabis cultivation methods demand precision and a huge investment of time. If you want bigger buds without all that hassle you need to FIM.