Topping cannabis plants is an old method suitable for both indoors and outdoor plants. It consists in essentially cutting off the top part of the plant. This is done to stop growth and force your plants to grow more branches rather than growing vertically. For each cut that you make, two Y-shaped branches will grow. The plant will recognize both branches as “central” stems. Don’t worry about losing yield using this method. The two new apical branches will produce a larger amount of smaller flowers.
Cannabis plants tend to naturally grow with a sort of pine, Christmas tree shape. This is essentially due to the fact that they’re genetically designed for being tall, skinny plants. You can use methods such as low-stress training (LST) in order to train the branches outwards and make for a wider plant. Although the best possible way to stop the plant from growing vertically is to top it. Remove the entire upper part of the plant.
Auxins are the hormones in charge of the shape cannabis plants’ take. The tip of the main stem is where the auxins come from, flowing down through the plant and stopping it from producing lateral growth. These auxins find it harder to reach the bottom of the plant, which is why when plants grow taller the lower branches grow out wider; giving them their classic Christmas Tree shape. However, topping allows you to remove the Apex (the top growth tip) and therefore break apical dominance, allowing side branches to grow more.
Topping Cannabis Plants: Why?
One of the main reasons for topping cannabis plants is lack of space or discretion. Cannabis can grow quite tall. Sometimes low-stress training simply isn’t enough to keep them down; whether you’re trying to keep them away from prying eyes or if you’re trying to fit them into a small grow room or tent.
Plus, successfully topping cannabis plants can also lead to quite a large increase in yield, especially outdoors and combined with a SCRoG when growing indoors. This pushes a lot of people to maximize their yield via the topping technique. Thanks to this method, you can fill out your trellis net, making sure that the light reaches each and every branch. This makes for amazing buds at the tip of each branch, maximizing your harvest.
How to Top Cannabis Plants
Once your plant has 5 to 7 leaf nodes it is strong enough to top. Keep in mind that this is a practice that stresses out your plants, so you’ll need to ensure that they’re as healthy as possible before beginning. You don’t want to top too low either, as depending on the strain, auxins may still be present when regrowth occurs, causing vertical growth again.
The general rule to follow is to cut your plant above the 5th leaf node in order to make sure that it’s sturdy enough to deal with the stress. You’ll also want to wait until your plants are at least 30 days old. This also leaves you with a decent amount of lower branches that can now grow outwards. Once you top it once, you can keep topping the two new branches, although make sure to top above the second or third node in order to give them time to grow out sturdy. Secondary toppings are usually only done by professional growers looking to grow absolute monsters outdoors and maximize yield.
First, you need to grab your tools clean them thoroughly. You’ll need your sharpest pruning scissors for this; as you’re looking for a clean cut. We highly recommend sterilizing your tools before using them. They come into contact with the plant in a way that can cause infection if they contain any bacteria.
Pick out the spot you want to cut. Topping requires you to get rid of the newest growth from the main stem entirely, completely removing the top of the plant. Topping creates two brand new branches that sprout from the cut. There is another more risky method called fimming which can create up to 8 new stems.
Once done, make sure to keep a close eye on your plants to make sure they’re recovering nicely. If cutting outdoors we highly recommend using Pruning Sealer For Cuttings in order to prevent any possible infections; these types of cuts make it really easy for fungi and bacteria to get to your plant.
Topping VS Fimming
Both of these techniques are often confused; while they may be similar, they actually produce widely different results.
Topping involves cutting off the top of the plant from the stem, above a leaf node. Fimming, however, is a clean cut through the new growth on the top of the plant. This technique is less harsh and traumatic for your cannabis plants; although it does require extensive plant training afterwards as the new stems created by this method can grow out quite weak. The term FIM actually comes from the phrase “f**k, I missed” and it’s thought that the first person to try this technique actually made a mistake when attempting to top their cannabis plant.
The FIM technique is done by grabbing the top of the plant and removing about 75% of the tip of the plant. It may not be the prettiest pruning method, but it is highly effective. It’s great for those with 1-2 plants in a small growing room. Keep in mind that fimming doesn’t actually slow down vertical growth as much as topping does.
A topped cannabis plant produces two extra stems that act like apex stems; producing thick and dense cannabis flowers. Fimming can produce up to 8 new stems that need to be trained. It’s a great way for novice growers with small grow tents to add a little extra to their yield.