how to prune marijuana

Why, when, and how to prune cannabis

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  1. Why do you prune cannabis?
  2. When do you prune cannabis?
  3. How do you prune cannabis?

Pruning is one of the most effective ways to manipulate and direct the growth of a cannabis plant. If you’re looking to limit the size of your plant, promote lateral branching, delay the onset of flowering, or increase yield, pruning checks all the boxes. It may feel counterintuitive to snip parts of your plant as it grows. But by pruning unproductive growth, you can redirect the plant’s energy and resources into developing quality flowers.

While pruning is reasonably straightforward, it’s also a skill that becomes refined and easier with practice. These pruning tips and tricks should help demystify the process.

Why do you prune cannabis?

Pruning refers to the process whereby small, specific sections of the plant are cut to encourage healthy growth. At its most fundamental level, pruning removes growth that is damaged, unproductive, or blocking sunlight from reaching budding flowers.

Pruning refers to the process whereby small, specific sections of the plant are cut to encourage healthy growth. Photo by: Gina Coleman/Weedmaps

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The elimination of this growth enables the plant to focus its energy on nourishing and strengthening the remaining leaves, shoots, and buds. Successful pruning also promotes greater airflow and light exposure, fostering a more vibrant plant, and forming denser, more cannabinoid-rich buds.

While the principle of pruning sounds simple in theory, in practice it can be challenging. Excessive pruning can be detrimental to the health and development of the plant. It’s vital to always err on the side of caution when pruning cannabis plants. Vigorous pruning can weaken the plant through stress and subsequently reduce the yield. Pruning at the wrong time of the growing cycle or mistakenly pruning vital stems and shoots can inflict damage. For this reason, some new growers avoid pruning altogether, or others pare back their pruning to its most fundamental level, the removal of dead or yellowing leaves.

When do you prune cannabis?

Pruning is almost exclusively carried out during the vegetative growth stage before the cannabis plant is mature and ready to flower. The plant should be well-established in the vegetative phase, measuring approximately 12 inches (30 centimeters) tall with several sets of leaves before pruning is performed. If you’re looking to grow bushy, squat plants, keep the pruning to a minimum.

Judicious pruning during the early phase of vegetative growth will have little effect on flowering. Pruning more mature plants that are approaching the flowering stage is not recommended. At this later phase, heavy pruning can delay the onset of flowering, or prevent flowering altogether. In some cases, however, growers may wish to delay flowering intentionally, so strategic pruning can be a useful tool.

Pruning during flowering should be extremely light and limited. One example of appropriate pruning would be the removal of fan leaves that are shading healthy bud sites. The pruning of damaged, diseased, or dead plant tissue can be carried out throughout both the vegetative and flowering cycles. Yellow (chlorotic) or brown tissue allows invasive microorganisms and pests to thrive. Remove these leaves to make sure they don’t fall and become absorbed into the growing medium.

How do you prune cannabis?

The process of pruning requires only one tool: a sharpened, clean pair of pruning shears. Expert growers may have several pairs of shears of different sizes designed to prune different levels of growth.

It’s vital to sterilize the shears before pruning to prevent pathogens from hitching a ride directly to your plant. The place where the plant has been pruned can be vulnerable to diseases or infections until it heals. Sharp shears are critical to making clean, swift snips that can heal quickly and don’t cause undue damage to the plant.

Once your pruning shears are sanitized and sharpened, you’re ready to begin.

1. Topping or primary stalk pruning

According to Robert Connell Clarke, a cannabis cultivation expert, trimming the central stalk represents one of the most common pruning techniques. The tip of the central stalk is removed when the plant has reached its desired length. This removal encourages a bushy, laterally spreading plant, rather than a tall, stringy specimen.

Beneath the point where the central stalk has been removed, axial branches will form and grow two new limbs that ultimately spread outwards. This practice, also known as topping , is transformative because it alters the plant’s growth trajectory.

2. Removing big branches and leaves

Pruning the larger branches and leaves promotes instant airflow by creating space. It also allows light to reach more of the plant. Make the cuts as clean and as close to the stem as possible, and at a 45-degree angle. Once the larger branches have been pruned, it’s easier to shift attention to the smaller details.

3. Clearing space around the middle of the plant

Branches growing in the middle of the plant are not as resilient as those at the top. Spend some time pruning to create space around the middle.

Branches growing in the middle of the plant are not as resilient as those at the top. Photo by: Gina Coleman/Weedmaps

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4. Lollipopping

Very small limbs or branches grow around the lower parts of the plant, and tend to be atrophied. The removal of entire limbs allows the plant to channel nutrition into the upper stems, leaves, and buds. More air circulates in the lower reaches of the plant, minimizing the risk of mold when growing indoors. Most importantly, energy and growth hormones are directed upwards towards the buds most likely to thrive. This method is colloquially referred to as the lollipop technique or lollipopping. The plant takes on a lollipop appearance: bushy at the top with skinny and sparse foliage toward the bottom.

5. Pruning the leaves and bud sites

Remove any yellow, brown, or diseased-looking tissue. Also prune any leaves that have branches shooting from their base. Snip any buds heavily shaded by the canopy branches. The unfavorable location of these buds means they will not have access to adequate light and may have nutrient deficiencies.

6. Allowing time for recovery

Pruning inflicts stress on the plant, so allowing time for recovery is vital. Make sure you provide adequate water, light, and nourishment in the days after pruning to facilitate recovery from the shock. Within a week the growth of new shoots and leaves should be apparent. You can prune again once the plant has had the opportunity to recover. Always remember, however, that the excessive removal of shoots and leaves is a significant stressor and can inhibit growth and bud development.

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When and How to Prune Marijuana Plants

Inicio » Tips » When and How to Prune Marijuana Plants

  • Escrito por : Ciara
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When and how to prune marijuana plants: depending on why you want to prune your plants, you’ll need to do it one way or another, or at a certain time or another. You wouldn’t prune the same way if you want to make a parent plant, then if you wanted your plant to have a more distributed production in order to have a more discreet plant or if it’s just the way that that particular variety is grown.

We’re going to talk about a few different pruning situations, along with a picture and an explanation so that you know where you have to cut depending on the result you want, because not all pruning is done the same or for the same reason, so each type has a different effect on your plants.

Where to cut if you want to get a clone:

To do this, you need to make sure that the part of the plant that you want to use as a cutting is above where you’re cutting, and that there are a few small branches on it. You also need to leave a knot above the spot where you cut so that when you plant it again you can plant it deep up to the knot, because that’s where the roots will be coming out of. You’ll need to cut it just like the picture, take off the little branch from the knot where we’ll be burying our plant, make sure that you cut it at a 45º angle, and then you should put it straight into some rock wool, jiffy, or whatever you prefer. After a few days, following the right steps (go check out the article we’ve done specifically on rooting clones), your plant should have some roots.

Where to cut with the FIM pruning method:

The FIM prune is a type of cut that’s not followed through on, and it produces 4 or 5 new sprouds. At the beginning they may seem strange and deformed, but they’ll soon turn into sturdy branches, you just need to give them time. This kind of technique is perfect if you want to turn a cutting from another plant into a parent plant. Using the FIM method, you can get a lot of new branches on your plant, which will cause new slip sprouts to appear on the upper layers, which is what you’re after. The first time I tried this I got very good results even though I had never done it before, even though it might seem difficult, you just need to try and leave the middle tip when the cutting is still small, like in the picture, taking away about 60% of the tip and leaving the little leaves that were starting to come out. If you want, you can repeat the process when the tip begins to come out again. You’ll end up having an extremely dense parent plant, which’ll be extremely productive, meaning you can have a SCROG set up with a mesh in your grow room or grow tent.

Where to cut to grow two central calyxes:

To get two central calyxes and have a more centered harvest, all you need to do is cut above the two branches that we want to let grow. The cut must happen after a point in which two new branches are appearing, leaving about 1cm of trunk after those two branches. In the picture we can see the two sprouts coming out of the trunk, and even a little extra bit. In a couple of days the wound will close and the two new central points will have your plants entire attention. That’s where the most bud will be concentrated because your plant will see the two new branches as the central eye of the plant.

Where to cut if you want a nice small, wide indoor plant:

To use this prune technique you’ll have to be a bit more careful, because you’ll have to cut along the fattest part of the trunk, and your plant will have an open wound that you’ll need to cover up. This way you’ll manage to get the plant to have a high density of flowers on the inner and outer branches, creating a blanket of buds of around 40x40cm with which you can fill a square meter grow tent with just four plants or a 1,2×1,2 grow tent with up to 9 plants. This kind of pruning helps spread out the production in the shape of smaller buds but in larger quantities. You’ll need to make the cut right around the height of the lower branches, leaving the plant looking kind of like a candelabrum, allowing the shorter branches to end up at the same height as the longer ones. You’ll need to use a scarring paste on the wound or even wax from a candle so that no dirt or insects can get in and put your plant’s life in danger.

Pruning lower branches to concentrate production at the top (Lollipop):

Some strains absolutely hate it when you prune them to increase their number of branches, so in these strains what you’ll want to do is increase the amount of production on the central stem. These strains tend to be indicas. The one that’s easiest to recognize with this kind of shape is Critical+. These plants center most of their production on the main “eye” of the plant, the central calyx, so to get the most out of these plants you’ll need to place a whole lot together and prune/trim the lower branches. This way you’ll be able to grow up to 16 plants per square meter without them getting tangled. The idea is to prune those branches that come out over the flowerpot, leaving just the main stem and 4 to 6 branches around the bottom. To make sure that it doesn’t end up doubling over with the weight you should wire or string it, and you’ll have 16 extremely productive plants where before you could only fit 9.

Doubling over branches to stop growth and increase strength:

If you take one of the branches on your plant and bend it slightly, it should form a sort of callus which will double the strength of the branch. The cells in your plant will make their way to the injury and they’ll strengthen the branch, allowing it to put up with much more weight. As well as not growing any more, the end bud will have heavier buds. All you have to do is bend the branch slightly, making sure not to go too far; if you actually break it then that’s that. If done correctly, you should end up with thick balls of buds and compact, strong plants. You’ll be able to grow less plants in your grow tent but with a higher production rate.

What not to do when pruning your plants:

Pruning is essentially cutting a part of your plant so that it can direct its strength to other parts that can absorb light easily. This doesn’t mean that you can prune any part of your plants like the large leaves so that the light can reach the lower parts. Leaves have an extremely important part to play in your plants’ lives; they’re kind of like solar panels for plants, and the buds are the batteries. If light hits the batteries they won’t charge, it needs to hit the panels so that the light can be turned into energy for your plants. This means that if you remove the leaves you’ll end up removing a lot of the strength from your plants, as they act like nutrient deposits; if your plants leaves aren’t receiving enough light the plant will automatically absorb all of the nutrients, leaving the leaf yellow and dead.

None of the leaves are disposable, even the smallest ones. Every single one is needed so that they grow properly. If you want to test this out yourself, trim one of the big leaves while your plant is still in the growth phase. You’ll notice how the branch carrying that leaf will stop growing, and branches with all of their leaves will continue growing without any issues. The same thing will happen to the buds; if you remove a leaf so that the lower buds can get more light, the higher buds will end up dwarfed and a lot less potent, when they would have been much bigger than the lower ones to begin with.

Another thing that you mustn’t do is prune your plants while they’re flowering. Plants need a few days to recover from prune-induced stress, and it takes a while to decide where the new branch or central stem is going to grow from. You’ll need to prune at least 15 days before you switch your plants to the growing period or before summer begins for outdoor crops. You need to prune during the growth period every time, or else the start of the flowering period may be compromised.

You can prune to change your plants’ shape, but never prune at the top to allow more light to reach the bottom; the top is always more productive than the bottom even if you want it to get more light. The logical thing to do would be to prune the bottom so that the top can produce even more.

If you’re looking to learn how to do other kinds of pruning, leave a comment and we’ll do our best to add it on to the article.

Author: Javier Chinesta
Translation: Ciara Murphy

Comprehensive article on when and how to prune marijuana plants depending on the effect you want the pruning to have. Read on to find out more.