Snapdragons (\(Antirrhinum majus\)) are a favorite among gardeners, recognized for their striking, upright flower spikes that add vertical interest to any bed or border. These plants, often grown as annuals, naturally tend to produce a single, dominant central stalk. Gardeners frequently employ a technique called pinching to manage the plant’s structure and maximize their flowering display throughout the growing season.
The Purpose of Pinching
Pinching directly manipulates the plant’s natural growth pattern by overcoming apical dominance. This phenomenon is driven by the growth hormone auxin, which is concentrated in the plant’s uppermost tip and actively suppresses the growth of lateral buds lower down the stem.
Removing the plant’s central growth tip eliminates the primary source of this growth-inhibiting hormone. This action stimulates the suppressed lateral buds to activate and grow into side shoots, redirecting the plant’s stored energy and resources.
The result is a bushier, shorter, and more robust structure. Instead of one tall, dominant flower spike, the snapdragon develops multiple stems, each capable of producing a flower spike. While pinching may delay the initial bloom time, the trade-off is a significantly fuller display and a greater overall number of blooms.
Timing and Technique for Pinching
Pinching should be performed at the correct stage of the snapdragon’s early growth. Seedlings are ready when they have reached four to six inches in height and established three to five distinct sets of true leaves.
The technique involves carefully removing the soft, uppermost growth tip just above a set of leaves. Gardeners should aim to cut directly above the second or third set of true leaves, counting from the base of the plant. This ensures enough foliage remains below the cut to support rapid new growth.
The tender tip can be removed using the thumb and forefinger, though small, clean gardening snips provide a more precise cut. After pinching, the plant focuses energy on the dormant buds immediately below the cut, leading to the development of new side stems. Ensuring the plant receives adequate water and fertilizer helps fuel the rapid development of these lateral branches.
Pinching vs. Deadheading
While both pinching and deadheading involve removing plant material, they serve fundamentally different purposes and are performed at different stages of the snapdragon’s life cycle. Pinching is a structural technique performed early in the vegetative stage to influence the plant’s shape and increase the number of stems.
Deadheading, conversely, is a maintenance task performed throughout the season once the plant has entered its reproductive stage. This process involves removing spent or fading flower stalks after the blooms have finished.
The goal of deadheading is to prevent the plant from diverting energy into producing seeds. By removing spent flowers, the plant is encouraged to continue producing new blooms in an effort to complete its reproductive cycle. This stimulates a continuous, prolonged flowering period.
Pinching is done once to establish the plant’s structure, while deadheading is an ongoing task to maintain continuous bloom production.