Pinching is a horticultural practice used on chrysanthemums (mums) to manipulate their growth habit. It involves removing the very tip of a young stem to encourage the plant to grow outward rather than upward. This method cultivates a full, dense, and well-branched structure capable of producing a spectacular display of fall flowers. By interrupting the plant’s natural growth pattern, pinching directs energy into creating multiple flowering stems instead of one tall, spindly stalk.
The Purpose of Pinching Chrysanthemums
Pinching disrupts the plant’s natural tendency toward apical dominance. This occurs because the terminal bud, the main growing point at the apex of a stem, produces the hormone auxin. Auxin travels down the stem and actively suppresses the growth of lateral buds located near the leaves.
Removing the terminal bud eliminates the source of growth-inhibiting auxin, causing the suppressed lateral buds to activate and grow into new side branches. This process transforms a single, upright stem into multiple new shoots, significantly increasing branching. More branches result in a bushier, more compact plant with a higher total bloom count. Without this intervention, the chrysanthemum would become tall and leggy, with flowers only appearing at the top of an unstable stem.
Critical Timing and Preparation
Timing is essential for successful pinching, as it directly influences the plant’s ability to set flower buds for the fall season. Pinching should begin in the spring when the plant reaches about six inches in height and the new growth is tender. For overwintered plants, this occurs when new shoots emerge; for spring-planted mums, it is usually a couple of weeks after transplanting.
The crucial deadline for pinching is mid-summer, generally between the last week of June and mid-July. Chrysanthemums are photoperiodic, meaning they initiate flower buds in response to the shorter day length and longer nights of late summer and fall. Pinching too late will remove developing flower buds, which can delay or prevent the plant from flowering before the first hard frost.
Before beginning, the plant must be healthy, actively growing, and well-watered. While sharp shears or scissors are an option, the term “pinching” refers to using your thumb and forefinger to cleanly snap off the soft, new growth.
Step-by-Step Pinching Technique
The physical act of pinching should be repeated consistently throughout the late spring and early summer growing season. For the initial pinch, remove the top half-inch to one inch of the main stem, targeting the soft, new growth just above a set of healthy leaves or a leaf node. The goal is to remove the active growing tip to force the lateral buds below the cut to break dormancy.
After the initial pinch, the plant develops new lateral shoots that grow outward and upward. Once these secondary stems reach four to six inches in length, they are ready for their own pinch. Consistently remove the tip of every new stem that reaches this length.
This process continues until the mid-summer deadline, often around the Fourth of July. Each successive pinch doubles or triples the number of stems, progressively building a dense, dome-shaped plant. After the final pinch, allow the plant to grow uninterrupted so it can begin setting flower buds in anticipation of shorter days.
Post-Pinching Maintenance
Successful pinching requires attentive care to support the resulting vigorous growth. The sudden surge of new lateral branches demands consistent moisture, so the soil should be kept evenly moist, especially during hot, dry periods. Lack of moisture can stress the plant and cause new growth to become woody or wilted.
To fuel the increased vegetative growth, the chrysanthemum needs regular feeding with a balanced fertilizer, such as a 20-20-20 formulation. A monthly application from spring until the final pinch provides the nitrogen needed to support the new shoots. Discontinue fertilizing after the final pinch to encourage the plant to transition from vegetative growth to flower bud formation.
Monitoring the plant is also important, as the new, tender growth is more susceptible to pests like aphids or fungal diseases such as powdery mildew. Ensuring good air circulation and watering the soil directly, rather than the foliage, helps minimize fungal issues. Consistent care ensures the new branches develop into strong, healthy stems capable of supporting a heavy blanket of fall blooms.