Chrysanthemums (mums) are popular fall-blooming flowers that require specific spring attention to ensure a spectacular autumn display. This early-season work shapes the plant’s structure to encourage dense, bushy growth. The primary goal of spring pruning is to promote lateral branching and maintain a compact height, leading to a greater number of flower buds later in the year. If left alone, mums become tall and spindly, producing fewer flowers and causing stems to flop over.
Preparing Mums by Removing Old Growth
The first step in spring care is cleaning up the plant from the previous season. Mums are cut back in late winter or early spring before significant new growth appears. Locate and remove all spent, brown, and brittle stems left over from last fall and winter.
Cut these old stems back aggressively, leaving only four to six inches of growth above the soil line. This removal makes way for strong, new green shoots emerging from the plant’s crown. Before cutting, clean your tools; wiping shears with a 70% isopropyl alcohol solution sterilizes them, preventing the spread of plant diseases.
The Technique for Shaping New Growth
Once new green shoots emerge and reach six to eight inches, begin the active shaping process known as “pinching.” This technique interrupts the plant’s natural tendency to grow vertically from a single main stem. Removing the stem tip forces the plant to activate dormant side buds, which grow into new branches.
The process involves removing the top one to two inches of soft growth on each stem, usually using your thumb and forefinger to “pinch” it off. This action stimulates the development of two or more side shoots from below the cut, effectively doubling or tripling potential bloom points. Repeat this pinching every two to four weeks throughout late spring and early summer as new branches grow another six to eight inches. Repeating this technique ensures a dense, dome-shaped plant covered in flowers in the fall.
Essential Care and Timing After Pruning
Immediately after each pruning session, the chrysanthemum requires specific care to support the vigorous new growth. Mums are heavy feeders, so a balanced fertilizer application is beneficial following the initial spring cut and each subsequent pinch. A balanced formula, such as 5-10-5 or 6-12-12, provides the necessary nutrients for robust stem and leaf development.
Consistent moisture is also necessary, as mums have shallow root systems and the new growth actively photosynthesizes. Water the plants deeply at the base to keep the soil evenly moist but never waterlogged, as saturated soil can lead to root rot. Establish a firm cut-off date for all pinching, which is generally mid-summer.
While the exact date varies slightly by climate and cultivar, stop pruning around the Fourth of July or no later than mid-July. This deadline is important because chrysanthemums are “short-day” plants; they initiate flower buds when periods of darkness lengthen in late summer. Pinching after this time removes developing flower buds, which will significantly delay the autumn bloom or eliminate it entirely.