Previously, we discussed the important cultivation step of pruning. This time, we explore the different methods by which to prune your marijuana plants.
Not pruning has several advantages. Floral hormones are allowed to concentrate in tips of branches, causing flower buds to grow stronger and denser. Indoors, short, un-pruned plants can be crammed into a small area. Crowded plants have less space to bush out laterally and tend to grow more upright. Clones are set into the flowering room after 1 to 30 days in the vegetative room. Pruning out spindly branches and growth inside plants opens up the interior and provides better air circulation. It also makes inspecting soil, plant stems, and irrigation fittings easier. This is a much better practice than removing all lower leaves.
Remove All but Four Main Branches
Remove the plant’s meristem (central stem) just above the 4 lowest (main) branches. Removing the central leader concentrates the floral hormones in the 4 remaining branches. The resulting fewer branches will be stronger and will bear a larger quantity of dense, heavy flower buds. Remove the stem above the 4 main branches, but do not remove leaves on the main branches. Select plants with 3 sets of branch nodes about 6 weeks old and pinch or prune out the last set of nodes so that 2 sets of branches remain. Move plants into the flowering room or greenhouse when they are about 12 inches (30.5 cm) tall. To maintain a low garden profile, varieties that grow fast and tall, such as ‘Critical Mass,’ ‘Power Plant,’ and similarly robust bloomers, should be set in the flowering room or greenhouse when about 8 inches tall.
Establish a bud count before pinching because only the next lower 5 to 7 buds will actually break or open and grow properly. If the plant is 10 leaves or nodes taller, a soft pinch of only the meristem and one leaf, will probably give about 5 breaks. If the plant is 15 leaves or nodes tall, then a soft pinch will give the same results, but all high on the plant. A harder pinch, the top 3 to 5 nodes down, may cause 3 to 5 good branches to grow below. This is a slower process that can extend the maturation period but adjusts the height overall.
Pinching Branch Tips
Pinching back or pruning tops (branch tips) causes the two growing shoots just below the cut to grow bigger and stronger. The effect is echoed down the plant. Pinching back and pruning branch tips increases the number of budding sites. It diffuses floral hormones (auxins). At high concentrations, auxins prevent lateral buds from growing very quickly. Lower branches develop more rapidly when the top of the plant (terminal bud) is removed. The further the tip of the branch is from hormones, the less effect the auxins have.
To pinch back a branch tip, simply snip it off below the last set or two of leaves. Pinching off tender growth with your fingers helps seal the wound and is often less damaging to plants than cutting with scissors or pruners. When the main stem is pinched back, side and lower growth is stimulated. When all the tops are pinched back, lower growth is encouraged. Continually pinching back, as when taking clones from a mother, causes many more little branches to form below the pruned tips. Eventually, the plant is transformed into a hedge-like shape. Most gardeners do not pinch plants back, because it diminishes the yield of prime, dense flower tops; but it may not affect the overall dry weight. Promoting many small buds also requires more work when trimming harvested buds.
Super-cropping is a form of pinching back or pruning branch tips. Regardless of who coined the buzzword, there are several different versions of super-cropping used by cannabis gardeners.
The theory of super-cropping is that plants respond to impaired fluid flow by producing more cannabinoid-rich resin and compact female flowers. The branch is folded over, approximately 2 to 3 inches below the growing tip, creating a wound. Some gardeners swear by this practice, and there might be a morsel of truth in it.
Super-cropping can also incorporate FIM pruning, which is explained below. It can be combined with bending, too. Removing healthy leaves so that “budding sites receive more light” is also practiced by some super-croppers who claim higher production. See “Stress,” on page 72 of the Cannabis Encyclopedia for more information.