How to Prune Cannabis

When reading the instructions for how to care for a particular type of weed strain, you’re bound to encounter the phrases “prune regularly” and “top early in its vegetative growth stage” (or phrases akin to these). If you’re relatively new to cannabis cultivation and/or gardening in general these instructions could understandably leave you asking: “What does this mean, and what’s the difference between topping and pruning?”

If this sounds like you, then this article is for you, and even for those of you who have experienced cannabis growers who encounter this question from friends, etc. “all too often,” and prefer to point them to an online resource as opposed to having to always repeat yourself.

To try and keep things as simple as possible, pruning is a training technique where you trim away small areas of your marijuana plant in order to encourage healthy plant growth in other sections of your weed plant.

Topping is a specific type of pruning method that involves pruning or trimming the growing tip of the main stem of your cannabis plant around day 30 of its vegetative phase in order to get larger yields and/or to prevent the plant from getting too tall by creating a pair of new branches, which results in fuller and bushier plants. Generally speaking, topping is a type of high-stress training (HST) technique used by more experienced outdoor and indoor growers.

As such, it would be accurate to say that while all topping is a form of pruning, not all pruning is a type of topping.

For the purpose of this piece, I’ll only focus on common pruning techniques that less-experienced growers can easily learn and master, so that they can eventually attempt more complicated HST methods like topping.

Pruning, aka “trimming,” is about removing damaged leaves and areas of unproductive or air- and light-blocking growth so that your weed plant is able to concentrate its energy on providing nourishment to the other sections of the plant. Some marijuana strains produce massive fan leaves, which usually don’t have trichomes, as opposed to sugar leaves, which are abundant in trichomes. For strains that don’t produce many or larger fan leaves, pruning is less important, but for ones that do, pruning is essential for ensuring healthy growth and healthy leaves because a plethora of big fan leaves layered on top of one another can block airflow and sunlight as well as causing moisture to get trapped, which can then result in damaging issues like mold and powdery mildew.

As such, pruning not only provides lower-growing nodes with increased access to sunlight and better air circulation but also allows your plant’s inner growth regions to “air out” and not become a sort of ground zero for diseases. In addition, promoting increased access to good lighting serves to increase the quantity and quality of bud sites.

All in all, knowing how and when to prune should provide you with healthier plants and bigger harvests with better quality yields.

While the actual act of pruning is far from difficult, knowing when and how much to prune can take some practice. This is because too much pruning can weaken the plant and cause its yield to be much smaller. In addition, carrying out pruning sessions at the wrong time or accidentally pruning viable stems and/or leaves can cause serious damage.

So, to start with, you should pretty much always and only trim your marijuana plants during their vegetative stage before they enter their flowering phase. It’s important that your plant is past its seedling stage and is far enough along into its vegetative growth phase before you prune it. As a general rule of thumb, your plant should be at least 1 foot (30.48 cm) tall with many clusters of leaves, or in its first couple weeks of vegetation.

If you prune too early, it will have little impact on the quality of flowers that your plant produces. At the same time, if you prune too close to your plant’s maturing into its flowering stage then bud production is likely to either be set back or completely prevented. (That said some veteran and commercial growers will purposely delay the flowering process, but because this article is geared towards sharing the basics of pruning, we won’t get into this type of advanced pruning technique.)

In general, you want to prune or trim off any fan leaves that are blocking air and light from getting to healthy bud-bearing branches. Other leaves to prune are those that have turned yellow or brown, as these are either dead, diseased or, at the very least, damaged leaves that are basically draining and diverting resources from your plant and its ability to provide you with maximum yields and denser, more cannabinoid-rich buds. Even if you’re a newbie to the world of cannabis cultivation, know that it’s safe to remove this kind of leaves all throughout the plant’s vegetative and flowering phases.

So, now that you know “why” and “when” to prune/trim your plants, let’s talk about how to execute the proper pruning of your cannabis crops.

To prune your plants you’ll need to make sure that you have a sharp pair of pruning shears that are sanitized. The reason you want to use clean and sterile shears is to prevent any pathogens from contaminating your plants as the area in which it is trimmed will be (temporarily) more susceptible to diseases until it’s fully healed. Also, the reason you need to only use sharp scissors is that you can make clean snips that don’t cause unnecessary damage to your weed plant(s).

Before you start to prune, remember to keep in mind that you don’t remove too many sets of leaves all at once as this can actually result in early flowering. Experts recommend that you first prioritize removing diseased and discolored leaves. Then, instead of removing all of the larger excess leaves all at once, it’s better to conduct your trimming in stages, leaving one week between sessions.

While every experienced cannabis grower will have their own strategic pruning techniques that are rooted in their years of knowledge and experience, the general methods for pruning are as described below.

• Step 1. After removing yellowed and dead leaves, then you’ll want to remove larger branches and fan leaves that are blocking light and air from reaching more areas of the plant. It’s imperative that your pruning snips are cut as cleanly and close as possible to the stem at an approximate 45-degree angle.
• Step 2. Having carried out the first stage of pruning, you’ll want to wait about a week before you start to do more trimming–at which point you should work on pruning lateral branches near the middle section. You want to do this because the branches in the middle aren’t as hardy as the upper branches are.
• Step 3. The next area to look at after trimming the mid-section of your plant is to look at the lowest branches, as these tend to be weaker and less resilient. Pruning these entire branches will make it easier for your cannabis plant to distribute nutrition to the upper leaves, bud sites, and limbs. This type of pruning is often referred to as “lollipopping” because your plant will look more like a lollipop where it’s bushy and full at the top and sparse near the bottom.
• Step 4. As previously mentioned, even if you’re not an expert grower, you can pretty confidently trim off any brown, yellow, pest-ridden, or diseased leaves even during the flowering stage. One other area to pay attention to is bud sites that are too shaded by what are known as canopy branches. If you find any of these, you should prune them as they are also draining your plant of light and nutrient resources.

If you’re a first-time or novice grower, you should not only expect to make some pruning mistakes but I’d encourage you to also embrace these incidents as learning opportunities and chances to increase your knowledge and experience.

Perhaps one of the biggest mistakes that inexperienced cultivators are prone to making s that of pruning too many of the fan leaves and/or pruning too often. A good measure to go by until you’ve gained enough cannabis cultivation experience is to not trim more than 1/3 of the fan leaves and to not carry out more than one or “bulk” pruning sessions. That said, it’s important that you don’t mix the number of large fan leaves and excess branches that you’ve pruned with the amount of dead, diseased, or pest-ridden leaves you’ve removed. In short, if you’ve pruned 1/3 of the fan leaves, don’t worry if you have to pull off a few dead or damaged leaves as well.

One last pro tip for successful pruning is to give your crops some extra vitamin B fertilizer and water after you’ve pruned them. This will help nurture the roots of your plant(s) and should help their buds to be larger and more resinous.