Since you’re constantly striving to get the best yield possible from your MMJ crop, there are two easy and practical ways to keep your entire crop blooming at it’s best—undercutting and thinning out.
Attempting an undercut for the first time can feel very awkward to a gardener. It tends to feel like you are hurting your plants or that cutting a good portion of them will destroy their potential yield. On the contrary, by removing the lower section of foliage, the plant will focus its growth on the remaining buds in the top portion, which are in an area of higher light energy. Medical marijuana is a very resilient plant, able to repair itself extremely quickly from even an aggressive undercutting.
I like to do my undercutting during the second week of the blooming period. By that time, most of the initial stretching period has passed, and a grower can get a good idea of the plant’s structure. I don’t recommend removing more than half of the plant’s foliage. If too much is removed, a plant can go into shock which will hurt potential yields.
I try to gauge the sweet spot of my light output (generally the top 18-30 inches of plant canopy) and remove as much foliage below that point as possible. Always cut leaves and stems off at the node, leaving the main stems as smooth as possible.
At harvest time, the grower that uses the undercutting technique will have larger top colas and overall less trimming work to do. This is truly a win-win situation.
Certain medical marijuana genetics grow numerous large fan leaves that can be thinned out to help boost flower production. I do not recommend removing all, or even most, of the fan leaves.
The fan leaves on a medical marijuana plant are like its solar panels. The majority of the light used for photosynthesis is captured by large fan leaves. That being said, there is an advantage to thinning out some of these fan leaves if they are impeding light penetration.
I usually remove approximately one-third of the fan leaves on the top portion of my plants to allow more light penetration. Again, like with undercutting, trim the leaves at the node to create a clean cut.
Because light diminishes exponentially, it is imperative to use any and all techniques available to better utilize light energy within our medical marijuana gardens. By implementing undercutting and thinning out techniques we can manipulate our plants into using the light more efficiently which, in turn, creates larger, denser buds.