Pinching out is a simple horticultural technique used to manipulate a plant’s natural growth habit. This process involves the removal of the soft, terminal growth tip from a stem. The goal is to redirect the plant’s energy to encourage a more compact, well-branched, and bushier form. Gardeners use this method to improve the appearance of ornamental plants and increase the yield of certain edible crops.
How Pinching Out Alters Plant Growth
The effectiveness of pinching out is rooted in apical dominance. This phenomenon is controlled by the plant hormone auxin, which is synthesized within the apical meristem, the actively growing tip of the main stem. Auxin travels downward, suppressing the growth of the dormant lateral buds (axillary buds) located along the stem at the leaf junctures.
When a gardener removes the apical meristem, the main source of auxin production is eliminated. This reduction in hormone concentration releases the inhibition on the lateral buds below the cut. Consequently, these suppressed buds break dormancy and begin to develop into new side shoots, changing the plant’s growth pattern from vertical to lateral.
The result is a denser structure with multiple stems instead of a single, tall stalk, which often leads to an increase in flowering sites. This redirection of energy from vertical extension to lateral branching is an effective way to manage a plant’s shape and productivity.
Proper Technique and Timing
The technique is straightforward, requiring clean snips or simply the gardener’s thumb and forefinger for softer stems. The growth tip should be removed just above a leaf node, the point where a leaf or pair of leaves attaches to the stem. Cutting at this point ensures that the newly stimulated lateral buds have a structure from which to grow.
Timing is important for achieving the desired bushy structure. For most herbaceous stems, pinching should occur early in the season when the young plant has developed a few sets of true leaves and is about 8 to 12 inches tall. This early intervention allows the plant sufficient time to recover and produce a robust framework before it shifts energy toward flowering.
The process may need to be repeated throughout the growing season to maintain a compact shape. For fall-blooming perennials, such as asters and chrysanthemums, pinching should cease around early July. This allows the new side shoots time to mature and set their flower buds for autumn display. A general rule is to remove only the top few inches of tender growth, or about one-third of the stem length.
Specific Plants That Benefit from Pinching
Many popular garden annuals and perennial flowers respond favorably to pinching, helping them transition from a sparse, leggy appearance to a full, floral display.
Annuals and Perennials
Zinnias, cosmos, and snapdragons are examples where removing the central growing tip early encourages numerous stems, resulting in a larger harvest of cut flowers. Early pinching of bedding plants like petunias and impatiens promotes a denser mound of foliage and more continuous blooming throughout the summer.
Culinary Herbs
Pinching is beneficial for culinary herbs and is often performed as part of the harvesting routine. Herbs such as basil, mint, and oregano should be pinched frequently. This practice prevents the plant from flowering, which can cause the leaves to become less flavorful. Consistently removing the top growth, usually about one-third of the stem, produces more leafy side shoots, increasing the harvestable yield.
Woody Ornamentals
Certain perennials and woody ornamentals also benefit from this technique to maintain size and shape. Dahlias are commonly pinched when young to encourage multiple sturdy stems capable of supporting their large blooms. Russian sage and garden chrysanthemums can be pinched back by about a third in the spring to promote a more compact, less floppy growth habit, ensuring they remain upright and attractive.