Cannabis plants naturally prioritize vertical growth, a phenomenon known as apical dominance, which results in a single main stalk and a characteristic Christmas tree shape. Plant training is the physical manipulation of the plant’s structure to interrupt this natural growth pattern, redirecting energy and growth hormones to lower branches. This technique is employed to create a wide, uniform canopy, allowing more bud sites to receive optimal light exposure. Applying these training methods increases the total harvestable yield by maximizing the productive surface area of the plants.
Training Techniques That Do Not Involve Cutting
Low Stress Training (LST) physically alters the plant’s shape without causing significant trauma to the tissue. This method involves gently bending the main stem and side branches, securing them into a horizontal position using soft ties or clips. The goal of LST is to break the plant’s apical dominance by ensuring the central stalk is no longer the highest point. When the main growing tip is lowered, the plant’s growth hormone, auxin, is redistributed more evenly across all lateral branches.
This hormonal shift encourages the side shoots to grow upward and develop into multiple main colas. The best time to begin LST is during the vegetative phase when the stems are young and pliable, minimizing the risk of snapping the tissue. As the plant grows, cultivators continuously adjust the ties, forcing new vertical shoots to remain at a consistent, low height. Maintaining a flat plane of growth ensures every potential bud site receives a similar intensity of light, promoting uniform flower development across the entire canopy.
Techniques Involving Pruning and Physical Stress
High Stress Training (HST) methods involve intentionally wounding the plant to provoke an adaptive response that encourages bushier growth and multiple main stems. Topping is a common HST technique requiring a clean, precise cut to remove the top growth tip just above an existing node. This removal permanently eliminates the main vertical growth point, forcing the two auxiliary shoots below the cut to become the new dominant colas. Topping is typically performed when the plant has developed at least four to six nodes, and the cut must be made using sterilized shears to prevent pathogens.
FIMming involves removing only 70 to 80 percent of the newest growth tip, leaving a small portion of the meristematic tissue intact. Unlike topping, which reliably produces two new colas, FIMming often results in the development of three to five new shoots. This makes the plant exceptionally bushy with a greater number of potential flower sites. Because FIMming removes less plant material, it is considered less stressful than topping, allowing the plant to recover and resume vertical growth quickly.
Super Cropping is a severe physical stress technique that requires crushing the internal tissue of a branch to make it flexible, without cutting. The cultivator gently pinches and rolls a mature, pliable branch between the thumb and forefinger until the inner fibers give way, creating a soft hinge without breaking the outer skin. The branch is then bent into a 90-degree angle, redirecting its growth horizontally and forcing the plant to send repair hormones to the stressed area. The crush site quickly develops a swollen, woody knuckle as the plant reinforces the damaged tissue, resulting in a stronger branch capable of supporting a heavier flower load.
Maximizing the Horizontal Growing Space
The Screen of Green (ScrOG) technique utilizes a horizontal mesh or net to evenly distribute the plant’s growth across the entire horizontal area. This approach maximizes the light footprint of an indoor grow light, ensuring no energy is wasted on shaded lower growth. The screen is typically installed a short distance above the growing medium. As the plant grows into the net, the branches are carefully tucked and woven into the grid squares.
This continuous tucking and weaving forces all growing tips to remain at the same level, creating a dense, flat layer of foliage that acts as a single, large flowering surface. The ScrOG method converts the plant’s natural vertical growth into an efficient horizontal spread, ensuring every developing cola receives direct light. The goal is to fill the screen completely during the vegetative period, creating a uniform plane of potential bud sites before initiating the flowering cycle. This structural aid allows the plant to support a greater number of large flowers because light is distributed uniformly across the grow space.
Maintenance Pruning for Improved Airflow
As the plant transitions to the flowering stage, maintenance pruning manages energy allocation and environmental conditions within the canopy. Lollipopping involves completely removing the lower branches and foliage that do not receive adequate light penetration. This process eliminates shaded, non-productive bud sites, redirecting the plant’s energy and nutrient resources exclusively to the upper colas that receive full light exposure. The resulting appearance resembles a lollipop with a bare lower stalk supporting a dense crown of upper growth.
Removing lower growth significantly improves airflow beneath the canopy, reducing the risk of stagnant, humid air pockets where mold and pests thrive. Defoliation is a complementary technique focusing on selectively removing fan leaves from the middle and upper parts of the plant. Strategic removal of large fan leaves allows light to penetrate deeper into the canopy, reaching developing bud sites on the interior. Both lollipopping and defoliation are most effective when performed just before or within the first three weeks of the flowering cycle, allowing the plant time to recover before flower development begins.