Topping is a high-stress pruning technique used in cannabis cultivation to deliberately alter a plant’s natural growth structure. It involves the precise removal of the main growing tip, or apical meristem, of the plant. This intervention redirects the plant’s energy and growth hormones, moving away from a single, dominant central stem to create a shorter, bushier plant with a wider, more productive canopy.
The Purpose of Topping
The natural growth pattern of the cannabis plant is governed by apical dominance. This process is driven by the hormone auxin, produced in the plant’s main terminal bud and transported downward through the stem. Auxin actively suppresses the growth of lateral buds and side branches, forcing energy and resources toward vertical growth and the main cola.
Removing the apical meristem breaks this hormonal dominance, interrupting the flow of auxin. This signals the plant to redistribute resources more evenly across the remaining lateral shoots. The result is a shift from a traditional Christmas tree shape, developing two new main colas directly below the cut site. This modification maximizes light exposure across the entire plant. By creating multiple dominant growth tips, growers achieve a more uniform canopy and potentially increase overall yield compared to an untrained plant.
Optimal Timing Based on Plant Maturity
Topping should only be performed during the vegetative growth stage, after the plant has established a robust root system and sufficient foliage to withstand the stress. Timing is determined by counting the number of true nodes—the points on the main stem where leaves and branches emerge. Growers generally wait until the plant has developed at least four to five true nodes before making the first cut.
Topping too early (at two or three nodes) can severely stunt growth because the plant lacks the stored energy to recover quickly. Waiting until the fourth or fifth node ensures the plant is vigorous enough to recover rapidly and redirect energy efficiently. Cutting at this stage helps keep the plant short and wide, which is advantageous for indoor cultivation. Topping must never be performed once the plant has transitioned into the flowering stage. This high-stress technique wastes energy needed for bud production, significantly slowing or halting flower development and drastically reducing the final harvest weight.
Executing the Topping Cut
The mechanical process of topping requires precision to minimize damage and potential infection. Tools include clean, sharp pruning shears or a sterile razor blade to ensure a quick, smooth cut. Sterilizing the cutting tool with isopropyl alcohol beforehand reduces the risk of introducing pathogens into the open wound.
The grower must locate the desired cutting point, which is just above the node they wish to keep. The cut should be made horizontally through the main stem, removing the newest growth tip and the leaves directly above the chosen node. A clean cut ensures minimal tearing of plant tissue, promoting faster healing and recovery. The cut should be made as close as possible to the remaining node without damaging the two lateral shoots that will become the new main branches; leaving a small stub of stem is unnecessary.
Post-Topping Care and Recovery
The plant will experience a brief period of shock, as topping is a high-stress training technique. Immediately after the procedure, the plant requires a stable environment to encourage rapid recovery and healing. Maintaining consistent temperatures and humidity levels helps the plant dedicate energy toward repairing the wound rather than managing environmental stress.
The initial recovery phase lasts between 5 and 7 days for a healthy plant. During this time, growers should avoid performing any other high-stress techniques, such as transplanting or heavy defoliation. The two branches directly below the cut will accelerate their vertical growth and become the new dominant colas. Monitoring the wound site for signs of mold or disease is important, though a healthy plant usually forms a protective callus over the cut within a few days. Once the new growth is visibly pushing upward with vigor, the plant is fully recovered and ready for the next phase of training or the transition to the flowering cycle.