Topping is a widely used technique by home and commercial growers to help increase plant yields and manage overall plant shape and structure.
Are you wondering how to top your own cannabis plants? We'll cover what topping is, why it's done, and how to do it below.
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Topped plants vs. non-topped plants: what's the difference?
When left to grow without human intervention, cannabis plants tend to take on the conical shape of a Christmas tree, spending most of its energy producing one prominent top or cola with a series of smaller budding sites below. These lower bud sites generally receive less light throughout the growing and flowering periods and therefore produce much smaller, larfy nugs compared to those found on the upper and main colas.
Topped plants fan outward so that more main colas can form and be exposed to light. Compared to non-topped plants, topped plants appear squat and wide.
In some cases, larger commercial grows may use the sea of green method (SOG), which employs a large number of untrained and naturally shaped plants in a facility where plenty of space and lighting is available. However, the natural shape of the cannabis plant tends to produce lower yields compared to plants that have been topped and trained. Because of this, growers employ a variety of training techniques throughout the plant's life cycle to maximize the output from each plant.
What is topping and why should you do it for cannabis?
Topping cannabis plants is one of the easiest and most common ways to increase yields at the end of the season since it encourages new plant growth. Topping is done by cutting off the growth tip of the plant, which causes more colas to form and can be done multiple times in a season, effectively doubling the plant's growth and potential harvest.
The process of topping slows down vertical growth and redistributes growth hormones, which allow lower branches to catch up to the main cola. The main benefit of topping, aside from spurring new growth, is prompting better light distribution. This is critical as light exposure directly impacts the weight and size of buds come harvest time.
Another reason growers top their plants is height management and lateral development. If you're a home or indoor grower in a confined or stout grow space, keeping your plants low and bushy rather than tall and lanky is incredibly helpful in increasing yields and keeping the plants growing at a manageable pace. Since topping divides the energy between two shoots rather than one, it slows overall growth down, allows the grower more time to make adjustments, and gives lower branches a chance to catch up.
If you're cultivating in a state with plant limits, topping can also be used to help increase yields with fewer plants and less overall square footage.
How to top cannabis plants
- Pruning shears
- Isopropyl alcohol
Step-by-step topping instructions
Time needed: 15 minutes.
Now that we have a general idea of the prerequisites for topping, let's dive into a step-by-step look at the process.
- Check your plant's overall health.
Before you go cutting up your plants, it's important to be sure your plant is ready and able to be topped so that it can recover appropriately and not suffer too much stress. Doing otherwise would risk the plant "herming" or becoming hermaphroditic and potentially self-pollinating. It should also be noted that topping should be reserved solely for the vegetative stage of the plant's life.
- Gather and disinfect your tools.
You'll need pruning shears or a razor blade — the sharper, the better — and some isopropyl rubbing alcohol to sterilize them and prevent infections from forming in the plant.
- Identify the main stalk.
To properly recover from being topped, the plant must have an established and healthy root system and should be snipped around the fourth or fifth node to ensure the plant bushes out properly. Cut above the fourth or fifth node on the main stalk with your sanitized shears.
- Keep an eye on the plant.
Keeping an eye on the plant in the wake of topping is important as topping causes plant stress, which can create even more problems with the overall growth. It's especially important to make sure the plant gets plenty of water and light afterward so it can properly recoup and continue growing. For subsequent topping on side branches, it's best to cut above the second or third node to continue creating the bush-like structure. These secondary cuttings to the side branches are optional and depend on a few considerations such as time left for vegetation, size of the grow space, and desired size of the final plant.
Tip: If you plan to top the main branch or other branches again, wait a few weeks in between sessions to allow the plant ample time to recover. Once the plant is in flower, stop topping or using other training techniques as they can over-stress the plant and detract from bud production.
A warning about topping
While topping is a great way to maximize each plant's potential harvest, it's important to do it right, or else you risk over-stressing or even killing your plant. To that point, topping shouldn't be overdone as the more you trim away, the longer it will take to recover, which can stunt the progress of your plant. Even if the plant is well into its growth period, too much stress can cause decreased yields, a notable drop in quality, or worse.
Additionally, not all varieties of cannabis plants will react well to topping and other training techniques, so some trial and error may be needed to see which strains respond positively.
Similar to topping, fimming — or the "FIM method" — differs as it comes about as a result of an improperly executed topping and is shorthand for “fuck, I missed."
Now regarded as a happy accident, fimming involves snipping only part of the new growth as opposed to fully removing the top of the plant. While topping may generate two new stalks, fimming can produce up to four. However, fimmed plants tend to grow unevenly and will need extra care and trellising to ensure optimal light distribution and provide structural support, whereas plants that were only topped tend to be more stable and have stronger branch structures.
Just like topping, fimming has the ability to dramatically increase yields and is especially useful for home growers and growers with limited space and plant counts.
Topping vs. fimming: what's the difference?
When it comes down to the choice to top or FIM your plants, the decision boils down to how much stress you want to put on your plants and how much time for recovery you have. Topping can be quite stressful for a plant as you're completely removing the top of the main stem, which can take the plant a while to recover from. On the other hand, fimming is slightly less stressful for the plant and doesn't involve cutting the entirety of the main stem, so recovery times are much quicker on average.
Another consideration is that topping creates just two new shoots whereas fimming can encourage many more stalks to form. However, the downside is that fimmed plants grow unevenly and can become unruly if not properly trained and addressed.
Whichever method you choose, observing your plants in the days following is critical in order to be aware of signs of poor health or any other stress-related changes your plant might experience.
Other plant training methods
While extremely effective at increasing yields and improving light distribution, topping and fimming aren't usually the only techniques applied to cannabis plants during their life cycles. Often, topped or fimmed plants also undergo other training processes like low-stress training (LST), the screen of green (ScrOG) method, and lollipopping.
Low-stress training is one of the most common techniques used when height in the grow space is an issue. It simply involves tying down branches to a desired height. LST is also commonly paired with the ScrOG method to help bush out the plants and keep their height to a minimum.
Paired with these other training techniques, topped cannabis plants can produce larger yields at the end of the grow cycle compared to their uncut and untrained Christmas tree-like counterparts. It's up to you to choose which technique suits your style and plants best, and experimentation is always encouraged in cultivation. You'll find some plants react very well to training whereas some might be a little finicky.
Overall, topping cannabis plants is a routine and highly recommended way to increase yields and grow bigger plants. While not necessary to produce smokable flower, it's a very useful technique for growers with limited grow space or plant counts as it allows them to improve yields and the overall quality of their final product.
It's also important to understand that using these techniques will stress your plants out and each cultivar of cannabis will react differently to this stress. This makes observation and aftercare of your plant very important. If topped in tandem with other training techniques, you're likely to see bigger, bushier plants bursting with glistening resinous colas and enjoy larger harvests from significantly fewer plants.