Pruning Leaves During the Vegetative Stage of Cannabis

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Why Do You Prune Cannabis Fan Leaves?

Was there ever someone from your childhood who made an important and positive difference in helping you grow into the wonderful adult you are today? That’s kind of what fan leaves are to a cannabis plant.

Marijuana plants produce two types of leaves — fan leaves and sugar leaves. Fan leaves, normally seven-petaled, are the larger, more distinctive of the two, and it is their larger size that enables them to absorb a greater amount of sunlight or artificial light to help in plant development. 

The energy provided by fan leaves through photosynthesis is crucial to a young plant’s development and in particular the buds immediately below them on a branch. As a result, their contribution should not be taken for granted. Of course, there comes a time in every young bud’s life when it is ready to continue on its own. 

Once dependent on fan leaves for growth, a developed bud no longer needs additional support. When that phase of development has been reached, it is often best to bid your fan leaves adieu.

Detailed Photograph of Cannabis Plant top

But if they are such true-blue friends to your plants early on, why shouldn’t you let fan leaves stay until harvesting? The reason that fan leaves are so important in early development–their size–is also the reason why they may inhibit growth later on. 

By trimming away those large fan leaves, more light can can reach down to help in the development of buds further below on the plant. In turn, those lower buds will grow faster. And that translates to a greater yield.

Trimming the fan leaves will also get more air to your plants and help to prevent the development of mold due to overcrowding. It will also help to expose insects and areas that are experiencing rot.

Just because you decide to part company with your once-helpful fan leaves, doesn’t mean they can’t be appreciated in their passing. While the leaves only contain trace amounts of THC and CBD, they can produce a mild buzz when made into a tea. They can also be used to make a soothing salve.

When Should You Prune Fan Leaves?

As mentioned previously, fan leaves have served their useful purpose when buds are developed. However, just because your fan leaves have reached their expiration date doesn’t mean you need to rush to cut them all loose. 

Technically, you can start to eliminate fan leaves once buds begin developing, but your plants will likely be healthier if you thin them out slowly by making cuts once every two weeks during the flowering stage.  After all, the goal is to open up more of your plant to sunlight, not to completely stunt the photosynthesis process.

How Do You Prune Cannabis?

Choosing which leaves to prune aka defoliate is a strategic decision, but dying or yellow leaves should always be the first to go. Additionally, starting at the bottom of the plant is recommended, as these leaves have a lesser value. 

When considering healthy leaves to excise, first consider if they might be allowed to remain and continue producing energy by tucking them aside in such a way as to allow light from above to get past them to developing buds below. If pruning seems the best option, start from the bottom of the plant again and consider which leaves you plan to remove first.

A gloved hand cuts leaves of cannabis growing outdoor

Cut them clean and close to the stem and at a 45-degree angle. A sharp razor can do the trick but there are many excellent marijuana trimming scissors you can find online that may make the process easier. 

Remember that each cut is a wound to your plant, so don’t overdo the process. Instead, after a few cuts, give your plants a couple of weeks to recover before attempting additional thinning. 

You want air to be able to move through your plant, but you still want to leave it with a good canopy.

What To Look For

Plants that have so many fan leaves, especially in the middle, that they are literally lying on top of one another are definitely in need of a trim. When they get to this point, they prevent sun or artificial light from getting through and air from circulating. A plant in this condition is a recipe for mold development and bud rot. And a poor yield.

Which Leaves Do You Cut and Which Do You Keep?

Candidates for removal should be the largest of the fan leaves near the bottom and in the middle of plants, and, of course those that are sickly in appearance. You should also excise any large fan leaves near the top that directly block sunlight from reaching developing buds. 

Smaller leaves that do not inhibit light or the movement of air should be allowed to stay for the time being. They can continue to work for the overall health of your plants.