Leaves off! defoliation techniques to increase your cannabis harvest

Di: Contributor Coltivazione

When performed correctly, defoliation is a highly effective technique that can significantly improve the yielding capacity and overall health of your cannabis plants. While this process carries certain risks, including excessive defoliation or causing further stress to an already sick plant, information and caution can help you avoid common mistakes. Here we explain everything you need to know about this method.

Defoliation is the process of removing the fan leaves and excess foliage of the plant. But this is more than simply cutting the leaves: it is a calculated technique aimed at improving the overall health and productivity of your crop.

However, the practice of cannabis defoliation often generates scepticism, especially among those who are new to the growing community. After all, why would you want to eliminate the leaves, which are essential for photosynthesis? The answer lies in the multiple benefits offered by this technique, each of which contributes to a healthier and more productive plant. So let’s analyse these advantages:

1- Increased exposure to light of the flowering shoots: in a dense plant canopy, the upper leaves can overshadow the lower parts of the plant, resulting in less exposure to light. By strategically removing certain leaves, you can ensure that light penetrates deeper, facilitating the growth of more robust and higher-quality buds throughout the plant. This is especially beneficial during the flowering phase when bud development is crucial.

2- Increased aeration, which reduces the risk of mould: a bushy canopy can also restrict the air flow, creating a humid environment that can be a breeding ground for mould and fungi. These issues can lead to a decrease in the yielding capacity of the plants and can also cause the harvest to be unsafe for human consumption. Defoliation opens the plant structure, which allows for better air flow and reduces the risk of these problems – something especially important in indoor grows where ventilation may already be limited.

3- Improved nutrient absorption: the leaves are the main elements for photosynthesis, which is the process by which plants convert light and carbon dioxide into energy. While it may seem counterproductive to eliminate them, the act of defoliation may actually improve nutrient absorption. But how? By removing selected leaves, nutrients that would have been distributed among many leaves can now be channelled to fewer leaves and, more importantly, to the flowers. This results in larger buds with enhanced flavours and increased potency.

4- Increased production of growth hormones: The best-known groups of plant hormones include auxins, gibberellins, and cytokinins. These “growth regulators” control the size and development of the plant. The production of these hormones can be stimulated by cutting the leaves during the flowering stage, so that they are directed towards the underlying growth sites. After defoliation, the buds will soon grow and swell as the plant recovers.

5- Cleaning your grow: Lastly, it is much easier to keep a grow clean when there’s no unnecessary wild foliage everywhere. It is also easier to spot complications before they become serious problems, such as intersex setbacks and pathogens that could ruin your crop.

Defoliation allows you to reduce humidity in a grow room

When to defoliate cannabis

There is no established rule as to when to defoliate or how many leaves to remove from your marijuana plants. Most growers use their experience and knowledge to judge the strain they’re growing on a case-by-case basis. Generally speaking, though, defoliation is usually done at the following times:

Vegetative stage

Is it too soon to defoliate during the vegetative phase? Not necessarily. According to the recommendations of experts, the ideal time to perform your first defoliation is one or two weeks before your plants move to the flowering stage. Begin by removing the large, hand-sized fan leaves that overshadow the lower growth. If you’re a rookie, limit the defoliation to the lower half of the plant and don’t remove more than 10-15% of the foliage. Start first with the damaged or yellowish leaves, and then move to the large leaves near the top of the plant that give shade. More seasoned growers may choose to remove up to 20-25% of the leaves, starting from the bottom and going up to 3 or 4 nodes from the top of the canopy. After defoliating, give your plants a few days of rest before changing the lights to a 12/12 schedule.

Flowering stage

The optimal time for a second round of defoliation is about three to four weeks after the start of the flowering. Most cannabis strains will go through a period of vigorous growth between the start of this stage and the third week of flowering. While it is incredibly important NOT to defoliate the plants during these 20–25 days of stretching, it is equally important to trim them once this period is over. That’s your last chance to prune any unwanted growth or leaves before your plant begins to fill with flowers. Focus on removing only the large fan leaves and be really careful not to disturb the young buds. The leaves will regrow in about three days, and in about 10 days the whole plant should have dense foliage again.

When should cannabis NOT be defoliated?

When performed correctly, defoliation can significantly increase the yielding capacity of cannabis. However, there are certain times and conditions under which this technique must be avoided:

  1. During the seedling phase: Plants are too young and fragile at this point, so defoliation could cause irreversible damage.
  2. Stressed or sick plants: If the plants are already suffering from stress caused by pests, diseases, or nutrient imbalances, defoliation can actually aggravate the problem.
  3. Outdoor grows with good light penetration: In outdoor environments where light penetration isn’t an issue, defoliation may not offer significant benefits.
  4. First-time growers: If you don’t have any experience, it’s easy to make mistakes that may damage your plants beyond repair.
  5. Autoflowering strains: These varieties have a short life cycle, and defoliation may cause them unnecessary stress.
  6. With extreme temperatures: Both extreme cold and heat can stress the plants, so defoliation during those times can be detrimental.
  7. If you’re unsure: Remember, defoliation is a high-risk yet highly rewarding strategy. Therefore, it is best to avoid it if you’re not convinced or if your plants aren’t enjoying optimal health.

Some common defoliation techniques

One problem with defoliation is the lack of solid general guidelines. Basically, it is about developing your grower’s intuition, which results from carefully observing the behaviour of your plants. Having said that, though, there are some common techniques which are used by a great number of growers:


This is a great technique that can be implemented during the flowering phase. It consists of trimming the lower half of the plant, only leaving between 20 and 30 cm of canopy at the top, with the branches taking on the shape of a lollipop. Lollipopping is excellent for after the third week of flowering, as it helps clean the small flowering shoots that would otherwise turn into popcorn buds. Its use is recommended indoors, where light intensity is significantly lower the further the leaves are from the light source.

Example of Lollipopping done at the beginning of flowering stage


The schwazzing technique, also known as simply “schwazze”, is a rather extreme form of defoliation that involves trimming the leaves during the flowering phase and removing all the fan leaves below the top three nodes at two key times: once at the beginning of the flowering phase, and again at the start of the third week of flowering. As with other intense defoliation methods, the idea behind schwazzing is increasing the yielding potential by providing maximum light and air penetration, whilst the plant’s energy is redirected to the upper flowering shoots.

Cleaning and defoliation

The death of the leaves is a perfectly natural stage of the growth cycle of cannabis. By removing the yellow leaves that are prone to falling, the plant is prevented from wasting valuable nutrients and energy on parts that will be shed anyway. Eliminating those leaves minimises the effort that your plant needs to grow. This means there’s more energy left to keep the leaves healthy and produce new ones. This is how defoliating cannabis plants can promote the growth and production of new branches, which in turn leads to new buds.

Defoliation prior to harvest

A week before harvest time, your cannabis plant will have gained most of its weight and will begin to focus on filling its trichomes with cannabinoids. That’s when most pistils are brown and trichomes turn milky and amber. It is recommended to defoliate one last time at this stage, as this causes a mild stress on the plant and forces it to direct all its resources to the buds, resulting in an increased production of trichomes and cannabinoids. What’s more, this can save you more than 50% of the manicuring time, because most of the fan leaves will have already been removed.


Mastering the art of defoliating marijuana can be a turning point in your growing process. However, it is essential to recognise that defoliation is not a technique for everyone. Timing is everything, and knowing when to defoliate (or not) can make all the difference in performance and bud quality. From the vegetative to the flowering phase, each stage offers a unique opportunity to optimise the health and yielding capacity of your grow. But remember: if your plants are young, stressed, or in less than ideal conditions, it may be better to skip defoliation altogether. Happy harvest!

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Kannabia accept no responsibility for any illegal use made by third parties of information published. The cultivation of cannabis for personal consumption is an activity subject to legal restrictions that vary from state to state. We recommend consultation of the legislation in force in your country of residence to avoid participation in any illegal activity.