Chrysanthemums are the quintessential flower of the autumn season, providing a vibrant burst of color. These popular seasonal flowers are often purchased potted and in full bloom, but their longevity depends heavily on understanding their specific needs. Mums belong to the genus Chrysanthemum, which includes thousands of cultivars, broadly categorized as florist types, grown for temporary display, and hardy garden types, bred to survive winter and return annually. Enjoying these plants beyond a single season requires implementing targeted care strategies once the colorful display begins to wane.
Maximizing the Current Bloom Cycle
The immediate focus after acquiring a blooming mum is to extend the life of the current flowers and encourage subsequent buds to open. Chrysanthemums thrive best when provided with ample light, ideally receiving at least six hours of full, direct sunlight each day. Proper light exposure helps the plant maintain dense, sturdy growth and ensures the development of vivid flower color.
Consistent moisture is necessary during the active flowering period to prevent wilting, which can cause the plant to drop its buds and blooms prematurely. The soil should be kept uniformly moist but never waterlogged, as overly saturated conditions can lead to root rot. When watering, it is best to apply water directly to the soil surface rather than overhead, which helps minimize the risk of fungal diseases.
Deadheading, which involves removing spent, faded, or brown blooms, prolongs the display. Deadheading redirects the plant’s energy away from seed production and toward the development of new flower buds. Using clean snips or fingers, remove the faded flower head just above the first set of healthy leaves or a new bud to keep the plant looking fresh and encourage further flowering.
The Transition: Preparing Mums for Dormancy
Once the last flush of blooms has completely faded and the foliage begins to yellow or brown, the plant is preparing for its dormant winter phase. This period is the correct time to prepare the mum for the cold, signaling it to conserve energy in its root system. A common practice is to cut back the dead or dying stalks to a height of about four to six inches above the soil line.
Pruning cleans up the plant, removing decaying organic material that could harbor pests or fungal diseases over winter. Removing the top growth signals the plant to focus its remaining energy reserves into the crown and roots for survival. The timing for this transition is after the flowers have finished but before a deep, hard freeze sets in.
Some gardeners choose to leave the cut stalks in place until spring, as they can collect insulating snow and organic debris to provide extra protection. However, the post-bloom cleanup, whether cutting back immediately or waiting until spring, is necessary for maintaining plant health and preparing the roots for the coming cold. This action ensures the plant is ready to enter a state of true rest.
Strategies for Long-Term Survival
Planting the chrysanthemum into the ground as soon as possible after purchase, ideally several weeks before the ground freezes, is the most successful approach. Potted mums purchased in autumn often lack the robust root system needed to survive the winter cold when left exposed in a container. Planting them in a well-draining garden bed allows the root structure to establish itself more deeply, increasing its chances of perennial survival.
Mulch insulates the shallow root system of the chrysanthemum from extreme temperature swings. Apply a three to four-inch layer of loose material, such as straw, pine needles, or shredded leaves, over the plant’s crown and surrounding soil. The mulch should be applied only after the ground has frozen solid to maintain a consistent cold temperature.
The insulating layer prevents frost heaving, which can push the mum’s roots out of the soil and expose them to drying winter air. For those in exceptionally cold climates or with potted plants, move the dormant mum to a protected, unheated space, such as a cold frame or an unheated garage, where temperatures remain just above freezing. The soil in these protected containers should be kept barely moist throughout the winter.