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Is it Safe to Defoliate Cannabis?

Created by
JoshuaHolt JoshuaHolt
Added 26 August 2020

Don't feel safe defoliating your cannabis plants? We're here to show you that cutting off a few leaves can actually do more good than bad.

Defoliation Can be a Beneficial Training Technique for Cannabis

Is Defoliating Safe?

It is perfectly safe to defoliate your cannabis plants and in fact, is encouraged as part of your standard plant care routine. It can be a nerve-racking experience the first time you cut anything off your babies but if you can face this fear, you may just end up with more bud! Let's go through the steps to defoliate your plant safely.

Defoliating cannabis has been practiced by many growers over the years. Trial and error is often the best way to go if you want to learn your strains really well. It is recommended you just try and see what works. Take it slow and you won't risk losing too much if anything goes wrong.

The main risk with defoliating plant is that one cuts off too many leaves. Defoliating cannabis plants is safe to do, so long as you don't stress the plant too much by removing too much foliage.

Before and After Defoliation

Most strains of cannabis benefit from some defoliation as they often grow a huge amount of leaves which can obstruct other areas of a plant that need more light. Even leaves blocking light from reaching other leaves can be a valid reason to consider defoliating. It is about trying to make the grow as efficient as you can.

Cleaning up older leaves that are browning and falling off means less chance of pests, fungus or rot. Any dying plant material should be removed if it looks like it is no longer providing energy to the plant. That means it looks brown and dead. Don't go pulling off all the slightly yellow leaves because these are still providing the plant with essential resources.

Tip: Small amounts of stress can be beneficial for your plant if managed in the correct way.

Yellowing Leaves is Normal Towards the End of Flowering

Yellowing leaves is normal towards the end of the flowering cycle. Photo by Philindicus from Grow Diaries.

What is Cannabis Defoliation?

Defoliation is the process of removing leaves from a cannabis plant to increase bud production. There are a few reasons growers defoliate their cannabis plants, but it is done mainly to direct the plant's energy towards the buds. How you defoliate will not only depend on your setup and growing method, but how much foliage your plants have.

Many growers swear by this method and believe it increases resin production. The theory is that by removing some of the larger fan leaves, more light reaches different areas of the plant. Bud sites can get covered by the fan leaves and limit the amount of photosynthesis happening in those particular areas.

Defoliation is not to be confused for 'lollipopping', which is the process of removing leaves from the lower parts of the plant, resulting in a lollipop shaped plant. This could also be considered defoliating, however defoliating describes a slightly different process which is more related to yields than for example, airflow or the prevention of rot.

Advantages and Disadvantages of Defoliating Cannabis

It is important to consider why you are defoliating your cannabis plants, and to decide if they actually need it or not. In most cases, a bit of defoliation does help a plant and if done correctly, can really allow your plants to make better use of the light.

Cutting off a plant's leaves will inevitably stress it out. Removing the fan leaves will cause the plant to try to photosynthesise through leaves surrounding the buds, which is essentially changing the plant's focus area.

Defoliating Makes More Efficient Use of Light and Creates Airflow

Advantages of Defoliating Cannabis:

  • Airflow around the plant reduces humidity levels
  • Decreases chances of mold
  • Pushes energy into bud production
  • Efficient light exposure

Disadvantages of Defoliating Cannabis:

  • Risk of stunting growth
  • Increased chance of pests/infection
  • Plants can become stressed if too many leaves are removed.

Tip: Always clean dead leaves up from your grow space. It can be a constant task, but is it well worth the effort.

How to Properly Defoliate Cannabis

In this section we want to go over how to properly defoliate a cannabis plant. First decide if it really needs defoliating. Some genetics will produce short and bushy plants with lots of dense foliage, while others will be tall and thin with skinnier, less obstructive leaves.

Some strains of cannabis produce more leaves than others so you need to have a good look at your plant and think about if it is worth defoliating.

You should not remove more than 20% of the plant's leaves, as this will cause too much stress and may affect its recovery and yield. To prevent stunting the plant or removing too many leaves at once, you can remove them in small batches. This way the plant has a few days to recover at each stage of defoliation and you will be able to see if it stunted the process.

NuggetPawn used defoliation on some Strawberry Lemonade. Notice how he didn't cut too much.

The safest time to start defoliating your plants is around 2 weeks before the flowering phase begins. This gives plants enough time to heal. You want the plant to be fully recovered before it focuses its energy on producing buds. If it is still trying to repair itself at the time when it should be producing buds, yield will likely decrease.

How to safely defoliate in 5 easy steps:

  • Disinfect a pair of sharp scissors - you can remove them by hand once you are experienced but this is not recommended as it can damage the skin of the stem. Exposed wounds on the plant increase the risk of pests.
  • Remove leaves that are dead/falling off - consider checking for dead leaves every few days to tidy them up.
  • Look at your plant to see where areas are being covered by fan leaves. Think about which areas could benefit from increased light exposure.
  • Snip 4-6 sets of fan leaves off with the scissors. You can also remove some of the leaves or new shoots on the lower branches up to 2 or 3 internodes up the main stem.
  • Do not cut off too many leaves - the plant needs them to photosynthesise. 

Sometimes it is not necessary to remove a whole leaf. If, for example, it is shadowing an area of the plant needs more light, you can shave/cut the ends of the leaf to allow more light to pass through. This way the plant receives more light in specific areas, but you don't remove the whole leaf, which has valuable nutrients stored in it for the production of buds.

Defoliated Cannabis Plants Can Become Slightly Stressed and Need Time to Recover

Defoliated cannabis plants can become slightly stressed and need time to recover. Photo by MrJu4nca from Grow Diaries.

Conclusion

Defoliating is often used with other growing techniques to maximise space efficiency, so it may be that you do not need it. If you do decide to defoliate, take it step by step and if you are unsure, only remove small amounts of leaves at one time. See how your plant recovers and decide if it is worth defoliating further.

If we've missed anything, give us your feedback with a comment and we will be more than happy to give you some more tips.

External References

Physiological Effects of Defoliation. - Heady, Harold & Child, R. (2019)

International Journal of Plant Science and Horticulture. - Emanuel, Machel & Henry, Valrick & Robinson, Dwight. (2020)

This article was updated August 2020.






Comments

Basement_Weed
Basement_Weed

You should not remove more than 20% of the plant's leaves, as this will cause too much stress and may affect its recovery and yield. To prevent stunting the plant or removing too many leaves at once, you can remove them in small batches. This way the plant has a few days to recover at each stage of defoliation and you will be able to see if it stunted the process.

This is a huge claim, do you have a link for this with any type of evidence?

Philindicus
Philindicus

Nice article. I think the key is knowing your strains and which phenotype will benefit from using defoliation. Breeders have been tinkering with traits like modest to longer inter-node stretch which typically results in more light reaching the bud sites which works out well. Unless your working with clones it's really hit or miss do to phenotype variables. Since I'm growing auto flower these variable do come into play often. I find that week 5-6 works out well to remove the lower 1/3 of the fan leaves and bud sites as long as you have plenty of fan leaves above that to keep up good photosynthesis. Leaf tucking and tying leaves back works well while in bloom. I try to preserve as many leaves as needed since the leaves tell you what's really going on with your plants. Once your getting toward late bloom and leaves are starting to show some fading strategically removing the large fan leaves allows more light to hit buds sites triggering trichomes to go into overdrive to protect the buds from damage. Checking your pistils and trichome ripening/color along with runoff ppms tells you when they have slowed down or stopped feeding this should be a sign to start your flush. My last week of waiting for the amount of amber trichomes to show that are to my liking I strip all the fan leaves off which saves a bunch of time during harvest. When it come to removing leaves protruding from the buds make sure to remove the leaves and the "entire stem". If you leave a piece of stem for too long it can lead to rot or mold issues to start in that spot especially with indica due to the tight and very dense bud structure.

Basement_Weed
Basement_Weed

Where in those cited links does it talk specifically about the defoliation of cannabis?