Chrysanthemums, commonly known as mums, are vibrant flowers often enjoyed as seasonal annuals during the fall, but they are actually perennial plants that can return to the garden year after year. These hardy varieties can be successfully maintained as permanent garden residents with the right care. Keeping mums alive year-round requires understanding their needs outside of the brief autumn blooming period, focusing on proper establishment, active season maintenance, and cold weather protection. Following a structured care routine ensures these popular flowers return to provide color for many seasons.
Transitioning Mums for Permanent Placement
The first step in establishing a perennial mum is selecting the correct planting location. Mums require a site that receives a minimum of six hours of direct sunlight daily to ensure robust growth and prolific flowering. Less light leads to weak, spindly stems and reduced bloom production.
The soil must be rich and well-draining because mums are susceptible to root rot in waterlogged conditions. Incorporating organic matter, such as compost or aged manure, before planting helps improve soil structure and drainage. Mums should be planted in the spring or at least six weeks before the first hard frost to allow root systems sufficient time to establish before winter dormancy.
When transplanting a potted mum, set the plant at the same soil depth it was in its container, avoiding burying the root ball. Mums have shallow root systems, so planting them slightly high can be beneficial for drainage. After placing the plant, gently firm the soil around the base to eliminate air pockets, followed by a thorough initial watering. Spacing plants 18 to 24 inches apart helps ensure good air circulation, preventing fungal diseases like mildew.
Active Season Care and Shaping
Once established, mums require consistent attention throughout the active growing season. Consistent moisture is necessary, as the shallow roots can quickly dry out, especially in containers or during high heat. Water deeply at the base of the plant, rather than frequent, shallow sprinklings, to encourage deep root growth and prevent wetting the foliage, which can spread disease.
Mums benefit from regular feeding during the spring and early summer when focused on vegetative growth. A balanced fertilizer, such as a 10-10-10 or 5-10-5 formula, can be applied monthly through July to support healthy foliage development. Fertilization should cease when flower buds begin to form, as late-season feeding can reduce the plant’s winter hardiness.
The technique of “pinching” creates a full, bushy structure and delays flowering until the fall season. This involves removing the top inch of the stem tips once new shoots are six to eight inches tall in the spring. Pinching encourages side branching, resulting in sturdier stems and a greater number of flower buds. Repeat this process every two to three weeks until mid-July, as pinching later may prevent the plant from setting buds in time for fall bloom. Removing spent flowers (deadheading) throughout the blooming period redirects the plant’s energy and prolongs the display.
Protecting Mums Through Dormancy
Successfully overwintering mums ensures they return as perennials. For plants in the ground, leave the stems standing after the blooms fade and the foliage is killed by the first light frost. Waiting to cut the stems back until late fall or early winter allows the plant’s energy to be redirected into the roots, improving winter survival.
Once the ground has frozen, cut the dead stems back to three or four inches above the soil line. This stubble helps anchor a protective layer of mulch applied over the plant crown. Spread a thick layer of four to six inches of straw, chopped leaves, or wood chips over the root zone to insulate the ground and prevent the damaging cycle of freezing and thawing.
Mums grown in containers require a different approach because their roots are more exposed to cold temperatures. Potted mums should be moved to a cool, dark, unheated location, such as a shed, garage, or cold cellar, before a hard freeze occurs. The ideal overwintering temperature range is between 32 and 50 degrees Fahrenheit, which maintains dormancy.
The stems of container mums should be cut back to three or four inches before moving them indoors. While dormant, the plants require minimal water, but the soil should not dry out completely. A light, occasional watering once a month is usually sufficient. In the spring, after the danger of hard frost has passed, gradually reintroduce the container mums to outdoor light and regular watering to break dormancy.