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pruning cannabis for maximum yield

Defoliation And Pruning Cannabis Plants For Maximum Yields

Growing cannabis can be done in many ways, every grower has their own techniques and tricks to increase their yields. One subject that is always subject to debate is defoliation: the removal of leaves. Do you defoliate your cannabis plant, and if so when and how much?

Defoliation Is A Pruning Technique

Pruning is any form of removing plant material to have a plant grow a certain way. Defoliating is a form of pruning that literally means removing fan leaves from a plant. Pruning has been used for thousands of years on many agricultural crops to increase yields and reduce the amount of smaller, unusable fruits. Most growers agree that this technique also works very well for growing cannabis and will incorporate defoliation into their grow cycles.

Tomato farmers might not have a cool name for it, but they’ve been “lollipopping” their plants for centuries!

Defoliation can be extremely helpful in terms of airflow and light use. Removing excess fan leaves and branches allows more air to pass through the lower parts of a cannabis plant and will reduce the threat of mold or bud rot.

Defoliation is often combined with removing branches, these are both forms of pruning but target different parts of the plant. Pruning helps to make sure lower parts of the plant receive enough light, which stimulates bud formation and ripening. There is also a limited amount of growth hormones that is distributed throughout a cannabis plant. The most well known groups of plant hormones include auxins, gibberellins and cytokines. These so called “growth regulators” control growth rate, size and development. Smaller, lower bud sites are often removed completely to focus all of these growth regulators towards the main colas. Besides increasing your yield, pruning your cannabis plants like this makes your harvest more uniform and much easier to trim. Techniques like “Lollipopping” (removing all lower growth from a cannabis plant) have become common in the cannabis community.

Before And After Defoliation

So Where’s The Controversy?

While most growers agree that defoliation and pruning benefit their cannabis plants, it is virtually impossible to find two people that do this the exact same way. Every grower will have a different opinion on when you should remove leaves and how many.

Technique

Growers use different techniques and tools for pruning and defoliating cannabis plants. Some remove everything by hand, bending and pinching as they go along. Others like to work a bit cleaner and use scissors or even razor blades that are cleaned with 96% ethanol before and after use. In our opinion the technique is not nearly as important as the timing and the amount of plant material you remove. We like to defoliate by hand, as leaves generally snap off easily when bent at the base. Make sure you have clean hands if you decide to do this! Other pruning and especially topping (and FIMming!) is usually easier and more accurate using scissors.

Timing

Defoliating a cannabis plant will have a slightly different effect in different stages of the cannabis life cycle. As with other pruning techniques, pruning and defoliating during vegetative growth is quite harmless. Even if a cannabis plant becomes stunted in veg, it will bounce back quickly and won’t be noticeable later on during flowering. Defoliating right before or at the start of flowering is common practice in a lot of gardens.

The first three weeks of flowering are probably the most productive period of growth in the life of a cannabis plant.

Defoliation during flowering is a bit more controversial, as stunting a cannabis plant anywhere in this 8-12 week window will probably affect the yield. There are are however many growers who like to defoliate during flowering with great success. They either gradually remove leaves to avoid any plant stress, or rely on their plants getting over their shock quickly. Our general rule is that defoliation and pruning is fine until about the third or fourth week of flowering. After a cannabis plant finishes stretching, we like to avoid any further defoliation. Gradual defoliation or stripping a cannabis plant in one session is both fine in our opinion, though we prefer the latter for practical reasons.

How Much Do I Remove?

Defoliating is a constant trade-off between production capacity and efficiency, it can be difficult to find a balance between the two. Defoliating can have all the benefits that we described earlier, but we also know that photosynthesis occurs in the leaves.

Growers that take a very light approach to defoliation argue that cannabis plants usually know what’s best for them. In their opinion defoliation is something that should only be done when necessary, like when airflow starts becoming a problem. Rather than picking off yellowing leaves, these growers will allow their plant to use every last bit of energy from them.

A lot of Kush varieties do fine without any defoliation. This Master Kush plant is flourishing without any pruning or defoliation

On the opposite end of the spectrum, you have growers that strip plants of nearly all their leaves and lower branches. These growers are convinced that a cannabis plant does not need many leaves once it starts flowering. They argue that a cannabis plant still has to dedicate a lot of energy to keeping their leaves healthy, energy that could otherwise be used for producing buds.

This Medical Kush grower likes to stay in full control of his canopy using heavy defoliation and a scrog net. This strain usually doesn’t require any defoliation, but it can increase yields by quite a bit indoors.

Defoliation is something most growers get into gradually, experimenting a bit more with each grow. Defoliation can seem very dangerous, as you don’t want to stunt your plant. In the following section we’ll discuss a video by a grower with a clear opinion on defoliation to show you what’s possible.

Video: Extreme Defoliation

The author of this video, HIGROWMEDICINAL, definitely likes to defoliate cannabis plants and makes a convincing argument that this increases yields. Let’s take a closer look at how he uses defoliation and his reasoning behind it!

The first thing you’ll notice is that the scale of this grow is huge: hundreds of cannabis plants and dozens of lights. Rather than scrogging, the grower has chosen to use tomato cages to support the plants, which allows them to be moved individually. The plants are all grown hydroponically, which increases vegetative growth in most strains. Keep this in mind before comparing this video to a soil grow!

How He Does It

HIGROWMEDICINAL starts by explaining that he is a bit of an “extremist” when it comes to defoliation. He removes virtually all fan leaves with a stem (= petiole) longer than a few centimetres. Many growers like to gradually defoliate their cannabis plants to avoid shocking the plant, but the author of this video disagrees. In his opinion it is better to get it all done at once to reduce the chances of shocking your cannabis plant later.

The leaf on the left has a long petiole or stem, the one on the right does not. The leaf on the right did not have its stem removed, but grew out of a bud site.

The best time to defoliate in this style would be after week 3 of flowering for 8 week strains, and week 4 for 9-12 week strains. Week 5 would be late, but is possible with many strains. The plants in the video are being stripped a day early at day 20.

This style of defoliation involves removing most of the large fan leaves except for a few at the very top of a cola. During this process, you’ll also want to remove smaller buds from the bottom of the cannabis plant. Sativa dominant strains will be easier to defoliate as they are generally less leafy. Over the course of this sped-up video, three plants are stripped in 20 minutes of real time. The author says he typically works with 12-20 light gardens, and usually spends about three days per grow to defoliate every plant by himself.

After explaining exactly how he defoliates, he explains that a cannabis plant doesn’t need big fan leaves after the third week of flowering in his opinion. While this is definitely a controversial statement in the growing community, this guy does seem to know what he’s doing! We’re impressed at least and “won’t knock it ‘till we try it”.

HIGROWMEDICINAL’s cannabis plant before and after defoliation.

HIGROWMEDICINAL goes on to explain that defoliating makes growing cannabis easier and more productive. It also makes his harvest free of small, larfy buds. He likes to think of his defoliating process as sort of a pre-harvest, making the final harvest much easier.

Our Opinion

Most growers won’t take defoliation as far as the grower in the video, but some interesting points are made. Given the amount of leaves removed, this video should be reassuring for growers that are afraid they will damage their cannabis plants beyond repair. The grower in the video also gives a nuanced view on stunting plants during flowering, stating that “they’ll be fine in a day or two”.

He’s definitely getting some great results, so he must be doing something right!

We generally like to defoliate more than the average grower, but this also depends on the medium. When growing cannabis indoors, we like to grow on coconut coir, mapito or in deep water culture. These hydroponic methods usually cause a cannabis plant to explode with growth during the vegetative stage and early flowering, making defoliation almost mandatory. In hydroponic indoor grows, we like to defoliate and prune our cannabis plants to the same extent as HIGROWMEDICINAL does in the video.

For outdoor grows we like to use soil, this gives us more stability but less explosive vegetative growth. Because of this, our outdoor pruning and defoliation routine is also less extreme than what we use for indoor hydroponic cannabis plants. Because the sun can penetrate deeper than grow lights, more lower branches can stay on the plant and only the smallest branches are removed. Fan leaves are removed if they are directly on top of a flowering site, or if they become damaged. Removal of fan leaves in outdoor grows is also very weather dependant, leading us to remove more leaves in weather conditions that promote powdery mildew and budrot.

Other Important Factors

There is definitely a huge difference in size between the grow in this video and the small home grows most people are running. The huge amount of plants in the grow room makes it clear that we’re dealing with a professional that might have different goals than a hobby grower.

The author states that he runs the whole grow by himself, this basically forces him to use as many techniques to reduce trimming time at harvest as possible. Growing cannabis at this scale makes using your time efficiently more important than in a smaller setup. The larfy, waste-of-time buds this grower describes might still be small treasures to people that grow a single cannabis plant per run.

A lot of home growers don’t really care if it affects their yield or saves them time, they simply want to avoid mold and larfy buds!

As mentioned before, the fact that the whole grow runs on HID lighting means that this style of defoliation might not necessarily be a good idea for outdoor plants. Sunlight can penetrate deeper into the canopy than HID lighting, this makes shading by fan leaves less of an issue when growing cannabis outdoors.

Finally the medium matters quite a lot when it comes to vegetative growth. A cannabis plant will generally perform better during veg when grown hydroponically than in soil. There are even large differences between different kinds of hydroponics. A cannabis plant will grow faster in coconut coir than in soil, but in more or less the same way. Techniques like deep water culture however will make your cannabis plants explode during veg and will end up forcing you to defoliate them. A good rule of thumb is that the more accessible nutrients are, the more foliage a plant will produce.

Try It For Yourself

By presenting a few different approaches to defoliation, we hope to have given you an impression of how many techniques exist. We’d like to encourage you to try it on your plants and start developing your own unique style. In any case, we’ve shown you that a cannabis plant can take a lot more than you might think!

Growing cannabis can be done in many ways, every grower has their own techniques and tricks to increase their yields. One subject that is always subject to

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.