DISCLAIMER: Everything taught and sold by BudTrainer® is to be used strictly for legal purposes. We condemn the production of illegal substances and it is your duty to ensure that you are complying with the law. The words "hemp", "cannabis", "weed", and "marijuana" are used interchangeably to refer to the same plant (legal hemp with less than 0.3% THC) for the purposes of this lesson.
Topping For The Top
Topping is one of the simplest yet most underrated techniques in cannabis gardening. If ignored, your plant turns into a Christmas-shaped tree that is flimsy, prone to breaking in the wind if you are growing outdoors, or growing so tall they hit your indoor grow lights. We know this all too well because we've made this mistake before, until we took to plant science and commercial cannabis production standards to create a topping method that works on both photoperiods and autoflowers. Welcome to BudTrainer's Lesson #3, where you will learn how to top like a pro.
Tools & Materials
- Sharp, thin-tipped trimming scissors
- Rubbing alcohol or isopropyl (for sterilizing your scissors before cutting)
When To Top Cannabis
The best time to top your cannabis plant is after the 6th node appears (a node is a pair of branches + leaves that grow 90 degrees from each other). This means you will have 5 formed nodes, and the 6th still pointing upwards. It typically takes 4 to 5 weeks from germination for a cannabis plant to get to this stage of growth."
To learn more about how your canopy develops and why topping works, read our article Canopy Development Science.
Transplant BEFORE Topping
It is also important to transplant your cannabis plants from your starter cups and into your final pots before topping them, as this will cause less stress to your plant both during topping and transplanting, and it will allow your plant to grow larger side branches after it's been topped. To learn more about when and how to transplant, read Lesson #2: How to Transplant Cannabis.
NEVER Top During Flower
The flowering stage is meant for making your much anticipated buds, not branches. In fact, topping your plant during flower not only reduces the amount of bud your plant will yield, but it also increases the chances of it becoming a hermaphrodite. This is why you should always top your plants at least 5 days before you switch them to flower.
How to Top Cannabis
Step 1: Make the Cut
Before making any cuts, sterilize your scissors with rubbing alcohol. Dirty tools can introduce pathogens through the fresh wound, which slows recovery and increases the risk of infection. A quick wipe with isopropyl alcohol is all it takes.
This part is the easiest - all you have to do is get a pair of sharp and pointy gardening scissors, and cut your cannabis plant between the 5th and 6th nodes, leaving behind 5 nodes, or 10 small branches and leaves.
The smaller your 6th node, the less shock to your plant. If you wait too long and the 7th node appears, now you will be removing too much plant material, thus risking stunting your young marijuana plant. So don't wait until it's too late and top your plants when those tops are still small and harmless.
BudTip: Be Careful With Small Growth Sites
When topping really close to the 5th node, it is not uncommon to damage the small growth sites that are just popping out. In order to avoid touching them, it helps slightly bending the top sideways (the 6th node) in a way that gets the tip of the pruners out of the way. Also, this is another reason why using thin-tipped pruners is so important - it will help you avoid damaging those delicate little branches that just emerged.
Step 2: Remove the 1st Node
Once you top above the 5th node, cut off both leaves and growth sites on the 1st node. The first node never grows into strong branches later on, and by removing it you help your plant send more energy to the 4 remaining top nodes.
This should leave you with a total of 4 nodes on the plant, or 8 small branches (also called growth sites) and 8 leaves. These 8 growth sites will now grow into your new main branches, which is how your plant becomes multiplied.
What to Expect After Topping
After topping, your plant will pause its upward growth for 3 to 7 days while it redirects auxins (growth hormones) to the lateral branches. During this time, don't panic if the plant looks like it has stopped growing - it hasn't. It's channeling energy into the remaining growth sites, which will soon become your new main branches.
During recovery, avoid any additional stress to the plant. Don't transplant, don't change your light schedule, and don't start training yet. Keep your watering and feeding schedule the same. The plant may drink slightly less water in the first 2 to 3 days after topping, which is normal.
You should see visible new growth from the top two nodes within 5 to 7 days. Once the new growth sites on the 5th node are about 2 inches long, your plant is ready for the first stage of training, which is the next lesson in The BudTrainer Method.
You Are Off To Crafting A Great Canopy
Now that you topped your plant for the first time, you can wait for 1 to 2 weeks until it is ready for the first stage of training - which is the next lesson on The BudTrainer Method. To know when your plant is ready for training, simply check the size of your top 2 growth sites - the ones on the 5th node that you just topped above. When they are 2 inches in length, this means it's time to start training them with LST clips, and the lower branches with garden wire and your fabric pots.
How to Top Autoflowers
Most growers will say that autoflowering weed plants shouldn't be topped since the technique is rather too "stressful" for them, and since they have a very short lifecycle, they don't have time to spring back from the pruning. Because of this, growers recommend that only low-stress training be used, instead of any pruning at all. Here at BudTrainer we have put this old adage to the test, and for the old-schoolers out there, we are sorry to say that topping actually works wonders for autoflowers. Here is an auto that we topped - it turned out to be the largest autoflower we ever grew.
As long as the techniques outlined in this lesson are followed, and very little plant material is removed from the autoflowering cannabis plant, they will continue growing as if nothing had happened. This is why it is important to top between the 5th and 6th nodes, but not too late, when the 7th node has appeared. This will ensure the minimal stress for your autoflower, and she will spring back to life in no time.
To learn how to low-stress train your autoflowers after topping, read our LST guide. And to understand why a level canopy matters for yield and bud consistency, check out our Canopy Development Science article.
Topping vs FIMing: The Difference
Topping and FIMing (short for "F*ck I Missed") are both high-stress training techniques that break apical dominance, but they work differently and produce different results.
Topping is a clean, full cut that removes the entire growth tip above a node. It reliably produces 2 new main branches from the cut site, and the results are predictable and easy to manage. Recovery takes 3 to 7 days.
FIMing removes only about 75% of the growth tip, leaving a small amount of tissue behind. This can produce 3 to 5 new growth sites from a single cut - more than topping - but the results are less uniform and harder to control. FIMing is also less stressful to the plant and recovery is slightly faster (3 to 5 days), but the new branches tend to grow at uneven heights, which makes canopy management more difficult.
At BudTrainer, we recommend topping over FIMing for most home growers. Topping is more predictable, easier to train around, and produces a cleaner branch structure that sets you up better for the training stages that follow. If you're interested in maximizing the number of colas from a single cut and don't mind less uniform growth, FIMing is worth experimenting with - but start with topping first.
Topping More Than Once
Can you top more than once? Absolutely - if you have 6 to 8 sq.ft of grow space per weed plant, you can top your plants for a second time after 1 to 2 weeks from the first topping, as you will learn in Stage 2 of Lesson #4: How to Train Cannabis.
This means you will be topping only the 4th or 5th nodes, since the 2nd and 3rd nodes never grow to become very strong. You can top your 4 top-most branches after 2 or 3 nodes from the main stalk, which means each branch will have 4 to 6 branches themselves, giving you that many more colas and future buds.
However, if you have 4 sq.ft or less of space per plant, you are better off not topping for a second time, and instead switching your plants to the flowering stage after training, during week 6 to 7 from germination. Topping for a second time will require you to extend your vegetative cycle until weeks 7 to 8, as the newly topped branches will need to be trained a week later, and before you flower your plant.
Topping More Than Twice
Although it's generally not advisable for indoor growing (unless you have over 15 sq. ft. per plant), outdoor growers can consider topping their plants a third or fourth time, usually 1 to 2 weeks after the last topping. This technique helps further 'multiply' the plant's growth. The plants shown below, for instance, were topped four times using the mainline training method.
Why Topping Increases Yields
To learn more about the science of canopy development, read this article.
i. Survival & Reproduction
Just imagine a field with thousands of cannabis plants next to each other that are all fighting for survival and reproduction rights. In order to survive, every cannabis plant must access water, carbon dioxide, and light. And in order to reproduce, pollen from the male plants must meet the flowers from the female plants.
There are two important things to note here: access to light and pollination. Cannabis plants grow tall and skinny rather than short and bushy because they want to stand out from the crowd and get as much access to sunlight as they can. Additionally, female cannabis plants need to pollinate. For this to happen successfully, their buds need to be far up in the sky as they can be. This makes them exposed and increases the chances that male pollen will land on them via the wind. Alternatively, if the plants are trained off to the sides and they have a lot of shorter colas, the probability of pollination significantly decreases.
For the sake of survival and reproduction, then, we can conclude that the female cannabis plant is not so concerned about the quantity of buds - it's a far better bet for it to have 1 amazing and exposed cola that will guarantee her reproduction rather than 100 smaller colas that will not catch light, or pollen.
ii. Breaking The Pattern
However, when growing cannabis at home, we kind of defeat the plant's two purposes of survival and reproduction. Here is why.
For starters, we purposely want to stop our female cannabis plants from reproducing, otherwise they would end up giving us bad, seedy weed. And we are also not worried about its survival, because we can give our marijuana plants lots of space, water, light, and love. In a nutshell, the whole purpose of cannabis plants having that single tall and exposed cola gets defeated the moment we don't need our cannabis plants to worry about reproducing and surviving anymore. Below is an un-topped cannabis plant on the left, and a topped and trained plant on the right. The different is clear.
So when you top your plant during the vegetative stage, you are basically changing its anatomy to grow into multiple large and juicy colas, but using basically the same amount of time. Topping cannabis plants not only increases yields but also guarantees a more even distribution of your buds, producing lots of tops that are full of cannabinoids. The next question is: why does it do that after it's been topped?
iii. Auxins & Apical Dominance
There are natural growth hormones produced during the vegetative stage in the top-most tip of almost every plant called auxins. Auxins are responsible for cell elongation, and are the main driving factor helping the plant and the lower branches grow toward the light. This is why when you bend a branch sideways it starts to grow back up - you basically shaded the bottom part of the branch and forced the bottom cells to grow more than the top cells, which is what causes the distortion.
Auxins are mainly present in new growth sites, and they are produced in higher concentrations in those growth sites that are closer to the light. In a nutshell, this is why a lot of plants grow like a Christmas tree - the auxins produced at the top growth tip are what promote this tall growth while keeping the side lower branches smaller since they are farther from the light.
iv. Shifting The Focus
Since most auxins are concentrated at the top-most growth tip, if you cut that tip off you completely stop the upper growth from happening. All of the auxins that were being produced there are suddenly removed. But since the plant still needs to grow, it starts producing auxins elsewhere.
When a cannabis plant loses its apical meristem (the main top) it shifts the production of auxins to the lateral branches, almost as if they each became an independent plant themselves. In fact, this sudden production of auxins in the lateral branches forces them to grow out and become the plant's new tops. This prevents your plant from reverting to vertical growth, like a Christmas tree shape, and instead produces a lot of bud tops for you to harvest later.
