Topping vs. fimming is a contentious high-stress training (HST) battle where both are winners. These advanced training techniques reduce the height of your main colas and allow the rest of the plant to catch up.
Although stunting the main growth point seems counterintuitive, it results in a more expansive and level canopy. You also get heavier yields due to comprehensive light coverage.
If you’re hoping to bolster your homegrown output, read on to find out about fimming vs. topping. We’ll show you how the experts prune their way to plump buds.
Topping vs. fimming: What is topping cannabis?
Topping is cutting off the head of the cannabis plant by slicing through the main stem during the vegetative stage.
Growth hormones are usually focused on the terminal cola. By lopping it off, they rush to the rest of the plant, energizing lateral branches.
Cutting off the head causes stress which stunts the top of the crop. It also allows the side branches to catch up. Stunting vertical growth is especially important in indoor grow rooms with limited space.
Under lights, plants push upwards towards the illumination source while the lateral branches sit in the shade. The hormone boost also improves side growth, widening the area the illumination reaches.
Topping cannabis plants also results in two main colas forming where there used to be one. Commercial growers repeat the process, making four, eight, and so on. This method takes full advantage of available light and boosts output significantly.
Topping aims to invert the Christmas tree shape of the marijuana plant. It produces bigger harvests with thicker colas, each getting a decent share of the light. It also reduces crops’ energy to create smaller “larfy” buds.
Fim vs. top: What is fimming cannabis?
Topping and fimming are similar HST methods for improved cannabis growth and bud production. Fimming cuts 75% of new growth at the top of the main stem, but the incision doesn’t slice the central stalk.
FIM is an acronym for “F***, I Missed” and refers to omitting the main stem. The snip results in four new heads growing from the same spot and stresses the plant less than topping. Less pressure means it also recovers more rapidly.
This method creates four heads each time, but plants still grow tall compared to topped ones. About five days of recovery are needed before regular growth resumes. Like topping, fimming allows cultivators to maintain a balanced canopy.
Fimming removes most of the new growth without touching the stem of your plant.
Topping and fimming benefits
In nature, plants grow toward the sun. As it moves across the sky, it gives crops complete access to its rays. Indoors, plants develop in the direction of the stationary lights, so the top bud (apical cola) gets the lion’s share.
This process is inefficient, so topping and fimming address this problem. These HST measures improve yields, increase light coverage, restrict height, boost plant health, minimize low-quality buds, and flatten the canopy.
Cultivators usually top photoperiod plants. We don’t recommend topping autoflowers unless you’re an experienced grower, as recovery time is limited.
The difference between fimming vs. topping
Fim vs. top is a longstanding debate. Outdoor farmers and commercial growers usually implement topping, while fimming works well for small indoor operations with limited space.
Here’s a brief breakdown of the topping process:
- It involves cutting off the top of the plant by severing the main stem between nodes
- It produces two evenly-spaced colas
- It can be very stressful to young plants, which take time to recover
- It makes plants bushier and strong enough to support heavy colas
- It reduces vertical height and powers lateral growth
Here’s an overview of the fimming technique:
- Slices most of the new growth off the top of the plant without harming the stem
- Results in four colas
- Not as stressful for plants, so they recover quickly
- Powers lateral growth, but plants may need structural support
- Reduces vertical height but not to the same extent as topping
While the difference between topping and fimming is only a few inches, both methods significantly impact output. It usually takes two weeks for plants to recover from topping, but only about five days from fimming.
Before settling the debate, you’ll need to buy and then grow your indoor seeds to at least a foot tall.
Is topping or fimming better?
Is topping or fimming better? See what works for your setup; you could try both methods side by side to highlight the differences, pros, and cons. Breeders successfully use these methods of pruning marijuana plants to elevate yields and boost bud quality.
Topping and fimming create multiple colas and expand the area that receives direct light, increasing yields.
Here are a few things to keep in mind when attempting these techniques:
- Use clean clippers or a razor to make the incision and avoid contamination, which could derail your HST before it begins.
- Don’t cut too early when the seedlings are too small, as they may die from stress. Wait until your plants are about a foot tall. Experts recommend at least 4–6 nodes for topping and 3–5 for fimming to work safely and effectively.
- Always use HST in the vegetative stage. Never stress your plants in the flowering phase, as it can compromise your harvest. Complete your pruning, and ensure they’ve recovered before you switch your lighting regime to induce bloom.
Our topping and fimming guide should give you an idea of which HST pruning style might work best for you.
The lowdown on topping and fimming
Choosing to top or fim is like picking between two champion fighters in different weight classes. Fimming seems like the winner because four heads are better than two, but it’s typically more complicated. Cultivators can repeat the process multiple times to create even more colas.
It also depends on your grow space. Small and micro-operations usually implement fimming, while outdoor growers and commercial farmers opt for topping. Although both pruning methods restrict height, fimming results in taller plants.
Why not put your knowledge to work? Buy top-quality cannabis seeds, germinate them, and watch them grow to a foot tall. Then, it’s time for your own topping vs. fimming test.
About the Author: Kyle Kushman
Kyle Kushman is a legend in the cannabis community. He is the modern-day polymath of pot: cultivator, breeder, activist, writer, and educator. After winning no less than 13 Cannabis Cups, there’s nothing this guy doesn’t know about indoor growing – he’s been there, done it, and is still doing it to this day!