As with all plants, cannabis plants benefit from occasional pruning. If done properly, it is possible to double yield through pruning alone. Pruning can lead to short, wide plants with lots of bud sites instead of tall, skinny plants with only a few large buds if desired by the gardener.
When growing cannabis, a desirable outcome is to generate the greatest number of high-quality buds, not the largest number of plants. (It isn’t the team with the most amount of yards gained in a football game, it is the team with the highest point score that wins the game.) Keep your eye on the right goal!
Benefits of Pruning
Increased Air Flow
Pruning plants increases the airflow beneath the leaves. This is important because unpruned plants are like a jungle, and like jungles, create breeding grounds for all sorts of problems including pests and pathogens.
Each time you cut a branch, the buds on top of the plant will grow larger. Plants have to spend energy growing leaves, stalks and buds. By trimming off the unnecessary leaves, more energy is left to put towards bud growth. Additionally, every time a bud site is pruned, two more will be created to take its place – leading to more buds on a single plant.
Removing extra leaves also allows the plant to put more effort into strengthening its stalk, an important factor when plants have a large number of heavy buds.
Decrease in Low-Quality Buds
Unpruned plants create large high quality buds on the top of the plant and low-quality “popcorn” buds on the bottom. These popcorn buds are not desirable because they are not dense or resinous and thus cannot be sold at premium prices.
When combined with trellising, pruning creates large plants with no lower buds. Instead, all bud sites are located on the plant canopy and receive equal amounts of light. This allows all buds to grow to a desirable size and density.
Less Plants Required
The increase in size and quality of buds means that less plants are needed to create the same size crop. While this may not seem like a benefit at first, commercial grows often have thousands of plants, and this can be a lot to manage. By reducing the number of plants required, labor costs decrease and more time can be spent checking each plant.
How to Prune Cannabis Plants
The first thing to know about pruning is that it is possible to have too many bud sites. Too many bud sites will mean that some buds cannot sit on top of the plant canopy, and thus do not get enough light and end up being smaller and less desirable.
At the end of the pruning process, each plant should have 4-5 branches with multiple bud sites. Each branch should be about 8 inches tall and be long and pliable – think vines. Cut leaves off as they form to create the long, lean branches. The stalk of the plant should be short and stocky in order to support the weight from future buds.
To start, assess the plant to see what it needs. Once it has three sets of leaves, it is time to start pruning. At this point, pinch the top node off. This will cause a new branch to begin growing. As soon as the plant recovers from the first pruning, about 1-2 weeks, pinch off the top node of each branch again.
At this point, you should have between 4 and 5 branches. Let these branches grow until they are about 8 inches long, removing leaves as they start growing. Then trellis the plant so that each bud site is at the top of the canopy and receives optimum amounts of light.
Pruning is now complete other than the occasional leaf trimming to keep the under part of the plant clear and allow air movement.·