Defoliation – A High Risk Way To Increase Yield

There are many ways you can intervene with a cannabis plant’s growth to improve yield quality and size. One of these methods, defoliation, involves stripping a plant of its excess foliage to improve light penetration and airflow.

While it’s a controversial method, we’re firm believers in its ability to improve the quality and size of cannabis yields.

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What is cannabis defoliation?

While it's simple enough, there’s definitely some risk involved with defoliation. Specifically, it’s all too easy to over-defoliate a plant, stunt its growth, and remove nodes that could’ve developed some great bud.

Many growers question defoliation. After all, why would a plant waste energy on growing unnecessary foliage? Well, in nature, cannabis plants use their leaves to store nutrients for stressful times like droughts, nutrient shortages, and pest infestations.

When you’re growing indoors, however, a lot of this excess foliage becomes unnecessary. After all, unlike out in the wild, indoor plants grow in carefully controlled environments with, ideally, perfect temperature and humidity levels and a low risk of pests. In this environment, the thick foliage becomes more of a burden.

That's where defoliation comes in; by removing some of this excess foliage, not only do you free up some of your plant's energy (by reducing the amount of foliage it needs to keep alive), but you help your plant make better use of its limited light source. Finally, defoliation also improves airflow around your plants, which in turn helps reduce temperature/humidity issues and the risk of pests/mould.

Note: Some growers confuse defoliation with lollipopping. While lollipopping does necessitate removing foliage, it involves stripping the entire bottom part of a plant, including the nodes (and sometimes removing entire branches), leaving the branches mostly bare like a lollipop stick. Defoliation, on the other hand, involves strategically removing leaves from different areas of the plant, and doesn't inherently involve removing bud sites or branches.

The benefits of defoliating cannabis plants

To better understand the benefits of defoliation, it helps to first understand that cannabis plants have a finite amount of energy at their disposal to fuel growth. This is governed by several factors, mainly the amount of available soil, the nutrient content of that soil, humidity and temperature levels, and the amount of light.

In an indoor grow room, you’re at liberty to give your plants the right nutrients just when they need them, and can control both temperature and humidity to a tee. However, the amount of light, soil, and space your plants have at their disposal indoors is far less than what they'd get in nature. By carefully removing foliage that won't support the development of buds, you'll be helping your plant make better use of the finite amount of energy it can produce with its limited resources.

Removing this foliage will also make it easier for air to circulate around your plants and the room. This in itself has a lot of benefits; not only will it help keep temperature and humidity consistent throughout your grow space, but it will reduce the risk of mould and pest infestations (which naturally flourish in warm, humid conditions).

Picking the right cannabis plants for defoliation

Removing healthy foliage stresses your plants. Hence, you should only defoliate plants that are 100% healthy; strong, upright stems, green leaves, fast growth, and a well-draining, fast-drying medium are all telltale signs that your plants are happy.

Don't defoliate any plants that look visibly frail or show symptoms of a nutrient deficiency, over or under-watering, nutrient or light burn, wind damage, or pests/disease. Defoliating these plants will only cause more stress than they can feasibly recover from.

We also only recommend defoliating indoor plants. As we mentioned earlier, cannabis plants actually store energy in their leaves for when they're exposed to stress. Because outdoor plants are exposed to more consistent environmental stress (like droughts, storms, harsh winds, or temperature/humidity fluctuations) as well as pests, we don't recommend defoliating them.

Plus, unlike indoor grow lights, the sun changes its position throughout the day and is capable of penetrating even extremely bushy plants, meaning outdoor plants get much more (and far better) light exposure. Thus, they don't benefit from defoliation in the same way as indoor plants.

How to defoliate cannabis plants

The key to properly defoliating cannabis plants is, of course, knowing what foliage to remove. At the same time, it’s also key to know when to defoliate. Ideally, we recommend defoliating your plants once during veg and once during flower.

If you're an inexperienced grower, only defoliate once during veg. If you are more experienced, you may want to try defoliating multiple times (given your grow schedule allows enough time for plants to recover after each defoliation).

Vegetative phase

We recommend defoliating vegging plants just before you switch them to bloom:

1. Start by removing big, hand-sized fan leaves first. These tend to overshadow almost anything below them, making it hard for light to properly penetrate your plant's canopy.
2. Next, remove any leaves that grow towards the inside of your cannabis plant. These also tend to overshadow important bud sites.
3. Finally, remove any old, yellowing foliage.

If this is your first time, we recommend defoliating only the bottom half of your plant. If there's any doubt about removing a particular leaf, play it safe and leave it in place. Don't remove more than 10–15% of a single plant's foliage.

If you're more experienced, however, we recommend defoliating from the bottom of your plant up to 3–4 nodes from the top of the canopy. Healthy plants should be able to handle having 20–25% of their foliage removed (given that you're not removing anything vital to your plant's development).

For even better results, combine defoliation with lollipopping and pruning to really help your plant make the most of its limited energy. Finally, once you've finished defoliating your vegging plants, give them 2–3 days of rest before switching their lights to 12/12.

Flowering phase

For best results, we recommend defoliating your plants a second time, roughly 3 weeks into the flowering phase. Follow the same steps listed above, but be a bit more prudent about the foliage you remove. Again, if you're a beginner, play it safe and only remove big fan leaves. Also, remember to be extra careful when handling your plants to avoid disturbing any of their young buds.

After this light defoliation, simply feed and water according to your regular schedule, giving your plants time to develop their flowers.

Knowing what foliage (and how much) to remove

Defoliation is an art form, if only in the sense that there are no definitive guidelines on how to do it. With time, however, you’ll automatically know what leaves to remove from your plants and how much cutting they can handle.

If you’ve never defoliated before, we recommend you always play it safe and stick to removing only the foliage that very obviously impedes bud production. In particular, focus on big fan leaves and interior foliage that’s already covering bud sites.

Quick tips to optimise defoliation

• The key to getting big harvests indoors is to grow low, flat, and wide. Your plants need a solid canopy to power their growth.
• Start low. Most of a plant’s bottom foliage is pretty safe to remove.
• Start slow. It can be easy to get lost in the rhythm of defoliating; then, before you know it, you’ve stripped your plant of half its leaves. Stay focused and move slowly to avoid removing too much. First-timers should aim to remove no more than 10–15% of total foliage at a time.
• Use sharp scissors. Our curved trimming scissors are great for making precise cuts when defoliating and trimming post-harvest. Remember to always keep your scissors clean to minimise the risk of disease and infection.
• Different strains can handle different amounts of defoliation. Bushy indicas, for example, tend to cope particularly well with defoliation, whereas sativas tend to naturally produce fewer leaves, and thus can't handle as much.

Defoliation vs pruning — understanding the differences

Pruning is a separate HST technique that many growers confuse with defoliation. The former is much more aggressive and involves removing entire branches and nodes in addition to leaves. While it might seem counterintuitive, pruning is actually very effective. It helps your plant focus its energy exclusively on the nodes that receive the best light. After that’s done, ideally, it’ll produce the biggest, densest, and most potent flowers possible.

Defoliation, on the other hand, only involves removing the leaves. That said, many cultivators use defoliation alongside pruning to optimise production, or they’ll use it alongside lollipopping, which we explained in more detail above.

Give cannabis defoliation a try!

To really maximise your plants’ potential, you'll want to combine defoliation with other training techniques like LST, main-lining, lollipopping, topping, and super cropping. As you get more experienced, you’ll learn how to finesse these techniques to produce bigger, tastier, and more potent harvests. No matter what you do, we hope you enjoy the process!