Chrysanthemums (mums) are a defining flower of autumn, providing color when most other plants fade. Many mums are perennial plants, but their ability to return depends on the variety and the specific care they receive. Understanding the plant’s biology determines if your mums will be a temporary seasonal accent or a long-term fixture in your garden.
Understanding the Chrysanthemum Bloom Cycle
The flowering of chrysanthemums is governed by photoperiodism, the plant’s response to the relative length of day and night. Mums are classified as short-day plants. They initiate flower buds only when the hours of darkness exceed a certain length, which occurs as the days shorten in late summer and early fall. This programming ensures they bloom aligned with the cooling temperatures of autumn.
A distinction exists between the two main types of chrysanthemums. “Garden mums,” or hardy mums, are perennial varieties bred to develop a robust root system. This system includes underground shoots called stolons, which allow the plant to survive winter dormancy and return the following year. Conversely, “florist mums,” often sold in full bloom, typically have shallow roots and were not intended to survive winter.
Florist varieties are often forced into dense bloom for a single season and lack the genetic hardiness or root structure to overwinter successfully. The natural bloom cycle concludes when energy is spent on seed production or when a hard frost causes the foliage and stems to die back. For a mum to return, it must be a hardy variety that successfully transitions into dormancy.
Techniques for Extending the Current Bloom Period
While a mum’s bloom cycle has a finite length, gardeners can employ techniques to maximize flowering duration. The most effective method is deadheading, which involves the removal of spent or faded flowers. This prevents the plant from diverting energy toward seed formation, which is its biological imperative after flowering.
Interrupting the seed-setting process forces the chrysanthemum to reallocate energy into developing remaining flower buds or producing new ones, prolonging the display. To deadhead effectively, use clean scissors or your fingers to pinch or cut the faded bloom just above the first set of healthy leaves or a visible side bud. This technique keeps the plant tidy and encourages a continuous flush of color.
Consistent mid-season care supports an extended bloom period by ensuring the plant has resources to sustain flower production. Mums require consistent moisture, especially when in full flower, so regular watering prevents wilting and stress. A light application of a balanced, water-soluble fertilizer can replenish nutrients used during the peak bloom phase.
Overwintering and Preparing for Next Year’s Blooms
For hardy garden mums to bloom again next year, they must be properly prepared for winter dormancy. If possible, plant the mum directly into the ground in early fall, allowing the root system several weeks to establish before the soil freezes. This establishment period is correlated with the plant’s ability to survive the harsh freeze-thaw cycles of winter.
After the mum has finished blooming or after the first hard frost kills the foliage, resist the urge to immediately cut the plant back. Leave the dead stems and leaves in place, as this material provides natural insulation to the plant’s crown. Once the ground has frozen solid, cut the stems back to about four to six inches above the soil line.
Apply a thick layer of loose, airy mulch (such as straw or pine needles) over the crown, aiming for a depth of three to four inches. This protective blanket insulates the soil, preventing the repeated freezing and thawing that can push the roots out of the ground (heaving). In the spring, once new growth begins, gently pull the mulch away. Then, begin “pinching,” which involves removing the growing tips of new shoots to encourage a dense, bushy form and maximize the number of flowers for the following autumn.