Cannabis defoliation is a growth technique base, as its name tells, in removing leaves from the plant, varying its vegetative process. This technique is not new (in farming its been used in potatoes, tomatoes and cotton growth; and is also common in gardening, specially in the art of bonsai. Referring to cannabis, the persistence trying to maximize performance of plants in reduced spaces, or with limited amount of plants, makes that adapting this farming technique to cannabis could be attractive to growers. Defoliation applied to cannabis growth consists in removing leaves off the plant in certain stages of growth, with the goal to get more quality and quantity per harvest. For this reason, this technique is specially useful for indoor gardens, and also for growers interested in maximize bud production.
Even though, cannabis defoliation is an aggressive technique, and its use it's not free from controversy, and has as many followers as detractors. In this post we will explain the process of defoliation, how to apply this technique, targets, and also reasons for and against cannabis defoliation.
Target of cannabis defoliation
If you are interested in this technique, before anything else, you should notice what results will you get from it:
Solve light exposure issues.
Increase yields without increasing the number of plants.
Reduce the budget in lighting equipment.
Manage growth, height and shape of plants.
Cause bud uniformity.
Avoid pests, and humidity problems.
Increase health and strength of plants.
How to apply defoliation technique to marijuana plants
Once we notice a yellow leaf, or not looking-good one, our fingers jump into it to trim it off. Even though, defoliation goes much more further. We will get rid of those leaves, but also we will remove the density of new-born leaves, so the light can penetrate to bottom of the plants, and also enhancing a better air-flow.
Tips before starting to defoliate
Cannabis defoliation is a quite easy process, but it has its own risks. Take your time, and be precise with your scissors. A wrong cut could harm future shots.
Some growers choose to do aggressive defoliations, leaving the plants almost naked, while others just remove few fan leaves. If this is your first time, trim just the big fan leaves, so you learn the technique slowly learning the results of each action. Remember you will always have options to remove more leaves, but once you trim too much there is no way back. Removing too many leaves could be definitive to your plants.
You must understand that defoliate and prune are two different concepts that you should not confuse. In cannabis defoliation we don't take branches off, only sub-shots and those leaves along those. the fact that you decide to defoliate your plants does not mean that you can not prune them (if you need to know more about pruning, read our post "How to prune cannabis plants")
The defoliation term is not too concreet. We talk about defoliation when we remove between a 20% and a 90% of the total amount of leaves off the plant.
Get some good trimming scissors to be precise in you cuts.
A sick plant, or not too healthy, shouldn't be defoliated, as it will hardly recover.
This technique is compatible with any growing method (soil, coco, hydroponics...).
We defoliate our plants along different stages, with different purposes in each stage:
Marijuana defoliation in vegetative stage
In this stage we will defoliate only once. Ensuring the plant is healthy and has grow enough (it should have at least 25 cm height). Remove only the biggest leaves, leaving enough leaves so the plant can continue with photosynthesis, and also processing nutrients so it can grow more and stronger.
Some growers start to remove leaves since plants start its blooming, because younger plants are easier to stress. Starting to remove while in vegetative stage we will train plants, and prepare them for further defoliations (even understanding that this could be risky). Besides, trimming off all those leaves will help us prevent some pests (as no leaves means no pests), with humidity issues like mildew. In addition, removing leaf density we will maximize light energy, that will arrive to lower areas, promoting also the airflow.
It seems that defoliation slows down root growth, what could cause imbalance in a a plant kept in vegetative stage. This deelay take long to recover, until plant has balanced again. To keep plants working again it is very important to feed them properly. if nutrient availability is low, defoliation will hit the plant hard.
We will need to be patient, as we are stopping the growing process of plants, and it needs to restart again. A defoliated plant will always grow slower than one following a "natural" process. If we did it right, in few days we will have a dense foliage again.
Marijuana defoliation in vegetative stage
Defoliation in flowering stage
Arrived at this point we will defoliate plants twice:
Once after the first week of flowering: Wait until first pistils appear (not one or two, you must notice the plant has fully started to flower). Remove all the big leaves you reach with your scissors, and leave the smaller ones. In about 3 days you'll see how these re-grow again, and after 7-10 days you'll have a dense foliage again.
Defoliation in flowering stage
Around 3rd week of flowering: Before attacking again, be sure your plants have recovered, and started to grow again, and repeat the previous process. you'll see buds have increased, and many are covered by leaves. Your mission is to expose them to light, specially the ones on the bottom of the plant, so there are no shadows. This is a risky point, don't cut too close to the buds unless you have a high density of leaves.
Around 3rd week of flowering
When cutting leaves along flowering stage we are stimulating auxins (the vegetable hormone that takes part in floral growth, and inducing rippenes. This way when the plant recovers, buds suddenly grow, swell abruptly.
Defoliating tops, and bottoms, the goal is to guide plant to focus its energy into buds. This way, we pretend to build bigger buds instead of those little ones (that once dried it end at nothing). The target is to get a final product of high quality, with dense and uniform buds.
* In this tutorial we recommend defoliate a maximum of 3 times. Some growers will choose to practice their plants a continuous defoliation along growing stage, removing all leaves every 7-10 days, every time they re-grow.
Pros and cons of defoliation
Walking through botanical readings, we've found dozens of articles (the most interesting ones you'll find at the end of this post) referring defoliation, and its effects in plant's sexual efficiency, on its leaves renewal, and also on its fruit production. The problem is that there are no studies about effects of cannabis defoliation, nothing but comparisons from growers and their own conclusions, then it is difficult to find a certain answer.
A plant with no leaves is something that impacts and, in some way, paradoxical. This is the reason, together with the lack of conclusions, to divide the opinion of growers. Up for the moment we gave you the kind part of this technique. Keep reading to know what other growers think about it.
Against
A plant needs leaves. Leaves not only act as solar panels, absorbing and transforming the solar energy to proceed with photosynthesis, and their internal processes, it also take the function of storing energy to use it later, when the plant requires it. So, when we remove part of the leaves we are not only removing the main receptors of energy of the plant, we are also removing that stored energy for when it is required.
Not all strains respond as good to defoliation. Every single strain reacts in a distinct way. The major risk of defoliation is that we don't know how is going to react our plant until we've seen the results.
Nature is wise. It will always be better to respect plants' processes, and let it grow naturally.
"When leaves start to develope again they do it healthier and stronger". Even there is some kind of true in this, the fact that leaves will regrow again and again takes so much effort for a plant, and that could exhaust it. So, we will get more uniform buds, and big, but the number of buds will be lower, these will be less dense, weight less, and def. will be lower quality.
Pro
You already know the targets, and advantages of this technique. Next we will synthesizethe argument with growers pro defoliation justify removing leaves.
Growing outdoors, sun is our source of energy, and plants grow adapting its shape to its trajectory, exposing and shadowing properly, taking and discarting nutrients needed, adapting to climate conditions. When we grow indoors we have the total control of the light, and the source of nutrients and enviromental conditions. Plants does not need anymore to store energy and nutrients in its leaves. Same way, it also doesn't need to have big leaves to get solar energy, nor protecting its fruits from sun, nor deep leaves to protect against pests.
What's your opinion on that?
Now you know how to apply this technique. Does it look extraordinary, or you think this is a barbarian thing= Compare your results and comment them with us. You can even try with a pair of clones and see what happens...
Sources:
The Role of Current Assimilate
Influence of Partial De-foliation on Photosynthesis,
Photorespiration and Transpiration
Effect of defoliate and growth substances on the development of the inflorescence in tomato
Annual Herb Abutilon theophrasti: Mechanisms Underlying Reproductive Compensation
This technique is specially useful when you grow big plants, as the bottom of the plant won't receive too much light if you don't remove those fan leaves. We'll wait for your future comments.
Best wishes
Don't get too mad with this. In your case what I would do is to let them grow longer so plants can recover from that extreme stripping. Once you'll get new leaves again you're plant will be ok to flip to flower. Don't do it before or you're gonna loose much yield.
Best
If your plants are in 6th week of flowering it is hard for them to recover as they are just few weeks left from harvest. Anyway, it will be better than it would be with fungi, so at least you'll get nice and healthy crop.
Best
If you already did a heavy one I would suggest you to let them go on their own now.
Best
With only 4-5 weeks left I wouldn't touch them at all. I really don't think plants can take advantage of doing so close to harvest. What you can do is to defoliate just one of the plants and see what happens with your own eyes and learn from the experience.
Best
I must say I prefer to do a heavy defo once than doing it twice, but is just a way of thinking, nothing against how you plan it.
Best
So our plants won't finish properly. It's such a shame.