Snapdragons (Antirrhinum majus) are popular for adding vertical interest and vibrant color to flower beds. They produce tall, striking flower spikes. Pinching is a horticultural technique involving the removal of a young plant’s primary growing tip. This intervention alters the plant’s natural growth habit, leading to a better display.
The Purpose of Pinching
Pinching overcomes apical dominance, the biological phenomenon where the main, central stem grows more strongly than the side stems. This dominance is regulated by the hormone auxin concentrated at the plant’s tip. Removing the terminal bud eliminates the primary source of this hormone, breaking the dominance over lower, dormant side buds. This forces the plant to redirect energy into developing multiple lateral shoots instead of just one main stem. The result is a stronger, more robust structure that produces more flower stalks overall.
Optimal Timing for Seedlings
The initial pinch must be executed at the correct stage of development. Gardeners should wait until the snapdragon seedling is approximately three to six inches tall. At this point, the plant should have established at least three to four distinct sets of true leaves. Pinching too early, when the plant has minimal leaf surface, can shock the seedling and hinder its recovery. Although this structural pinch delays the first flush of blooms by a few weeks, the resulting increase in flower number provides a greater long-term yield compared to an unpinched plant.
Making the Initial Cut
The mechanical process of pinching is straightforward, but precision ensures the best outcome. The objective is to remove the very tip of the main stem by cutting it back above a set of existing leaves, known as a node. The cut should be made just above the second or third set of true leaves, counting up from the base. Using a pair of small, clean, sharp snips or a clean fingernail provides the best cut. A sharp implement creates a clean wound that minimizes the risk of introducing pathogens. New lateral shoots will emerge from the leaf axils immediately below the cut.
Extending the Flowering Season
Once the initial flower stalks have bloomed and faded, deadheading is used to extend the season. This secondary form of pruning is performed continuously throughout the growing season. Deadheading involves removing the spent flower spike to prevent the plant from diverting energy into setting seed. When the blooms on a stalk have finished, the entire stalk should be cut back to a strong leaf node or a healthy side shoot. This prompts the snapdragon to produce new flowering stems, encouraging a succession of blooms that can last into the cooler temperatures of the fall.