Chrysanthemums, or mums, are a quintessential symbol of autumn, providing a burst of color when most other flowers fade. Many people purchase these vibrant potted plants late in the year, assuming they will return the next fall. This expectation often leads to disappointment because the perennial nature of a potted mum is not guaranteed. Whether a mum comes back depends entirely on the specific variety purchased and the timing of its planting and care. The market offers two distinct types of chrysanthemums, each bred for a different purpose.
Understanding the Two Types of Mums
The primary factor determining a mum’s return is the distinction between “Garden Mums” and “Florist Mums.” Garden mums, derived from Dendranthema grandiflora hybrids, are bred to be true perennials with developed root systems that allow them to survive winter dormancy. These varieties are typically hardy in USDA Zones 5 through 9, meaning they can withstand freezing temperatures if properly established. Garden mums develop underground shoots, or stolons, which help them anchor and return each spring.
Florist mums are cultivated specifically for their dense, showy, and abundant fall blooms. These varieties are most commonly found at retailers in the fall, often heavily root-bound in small pots. Florist varieties are not bred for winter hardiness and possess shallow root systems, making them ill-equipped to survive freezing temperatures. They are best treated as seasonal annuals, regardless of the climate.
Even a true garden mum purchased late in the fall may fail to return due to insufficient time to establish its roots. Mums are short-day plants, meaning they set buds and flower when daylight hours shorten late in the growing season. If planted in October, the plant’s energy focuses on blooming, not developing the deep root structure needed to survive the winter soil freeze. This lack of establishment is a common reason why even hardy varieties do not reappear.
How to Plant Mums for Successful Return
To maximize the chance of a garden mum returning, planting time is key. The optimal time to plant hardy chrysanthemums is in the spring or early summer, allowing the root system to establish deeply before the first frost. If planting in the fall, place the mum in the ground at least six to eight weeks before the ground is expected to freeze solid. This window gives the roots enough time to grow outwards and anchor the plant.
Site selection is equally important for long-term success, as chrysanthemums require at least six hours of direct sunlight each day. The soil must be well-draining, since mums are highly susceptible to root rot if they sit in overly wet conditions during winter dormancy. If the soil is heavy clay, incorporating compost or other organic material will improve its structure and drainage.
When planting, the mum should be placed in the soil at the same level it was in the nursery pot, or slightly deeper, to encourage new root growth. It is beneficial to gently loosen or score the root ball before planting, as potted mums are often densely root-bound, inhibiting the roots from spreading. Immediate and consistent watering after planting is necessary to settle the soil and help the roots begin to grow into their new environment.
Winter Care and Overwintering Techniques
Once a hardy garden mum is established in the ground, proper winter care is necessary to ensure its survival through freezing temperatures. It is advised to leave the dead stems and foliage intact after the blooms fade in late fall. This withered material acts as a natural layer of insulation, helping to protect the plant’s crown and root system from the cold.
After the ground has frozen solid, apply a thick layer of winter mulch around the base of the plant. Mulching with materials like straw, shredded leaves, or pine needles insulates the soil and prevents freeze-thaw cycles. These cycles can cause the plant to heave out of the ground and expose the roots. The mulch layer should be substantial (four to six inches deep), but avoid piling it directly against the stems, which traps moisture and causes rot.
Overwintering Potted Mums
For those who purchased a potted mum too late to plant or who have a florist variety, overwintering the container is challenging. The roots of potted plants are highly vulnerable to cold, as the entire root ball is exposed to temperature fluctuations. A practical approach is to move the container to a cool, dark, and unheated location, such as a garage, shed, or basement, after the plant has gone dormant.
The goal of this sheltered storage is to keep the mum dormant by maintaining temperatures just above freezing. While in storage, monitor the soil monthly and water sparingly to prevent the roots from completely drying out. Overwatering during dormancy will lead to root rot. When spring arrives, gradually reintroduce the plant to outdoor conditions, protecting it from late frosts until it is safe to plant in the garden.