Chrysanthemums, commonly known as mums, are popular seasonal flowers prized for their diverse color palette and ability to provide vibrant displays when most other plants fade. These colorful blooms signify the shift from summer into autumn. The best time to plant mums depends on the gardener’s goal: seeking a temporary annual display or a permanent perennial addition to the garden bed.
Planting Mums for Long-Term Establishment
Establishing mums as permanent perennial plants that return each year requires careful attention to timing, prioritizing root growth over immediate flowers. The optimal period for planting is in the spring, once the danger of the last hard frost has passed and the soil is workable. Planting at this time allows the mum to dedicate its entire summer growing season to developing a robust and deep root system.
An established root system is the single most important factor for a mum’s ability to survive the cold winter months. If a spring planting is not possible, the latest recommended time is in the early fall, at least six to eight weeks before the expected date of the first hard frost in your region. This window provides the minimum necessary time for the roots to anchor the plant and resist the effects of soil heaving during winter freeze-thaw cycles.
Planting Mums for Immediate Autumn Color
Mums purchased for a seasonal burst of color are planted in late summer or early fall when the plants are mature and heavy with buds or flowers. The goal is instant visual impact, treating the plants primarily as a decorative annual display. When selecting plants, choose compact, healthy specimens with many tight, unopened flower buds rather than those already in full bloom.
Selecting plants with buds ensures a longer period of color, as the flowers open gradually over several weeks. Because these plants focus entirely on flowering, they often lack the energy or time to establish the vigorous root system needed for overwintering. Consequently, many autumn-planted mums are simply treated as annuals.
Soil Preparation and Proper Planting Technique
Regardless of the planting season, the site selected must receive at least six hours of direct sunlight daily to promote strong growth and abundant flowering. Mums thrive best in rich, well-draining soil, as they are highly susceptible to root rot if left in soggy conditions. Incorporating generous amounts of organic matter, such as compost or well-rotted manure, into the planting bed improves both drainage and nutrient content.
To plant, dig a hole approximately twice as wide as the mum’s root ball but no deeper than the container. Gently loosen any tightly coiled roots before placing the plant so the top of the root ball is level with the surrounding soil surface. Planting the crown too deeply can lead to stem rot. Allow adequate spacing between plants (typically 18 to 36 inches, depending on the variety) to ensure good air circulation and prevent fungal diseases.
Essential Care After Planting
Immediately after planting, give the mum a thorough, deep watering to settle the soil around the roots and eliminate any air pockets. Maintaining consistent moisture is important, especially while the plant is establishing itself, so water whenever the top inch of soil feels dry to the touch. Avoid overhead watering, which can encourage leaf spot and powdery mildew; instead, direct water flow to the base of the plant.
Summer Pinching
For spring-planted mums intended for perennial life, a technique called “pinching” is necessary to create a full, bushy shape and maximize the number of autumn flowers. Begin pinching back the stem tips when new growth reaches about six inches, removing the top one to two inches of growth. Repeat this process every few weeks until early July, which encourages lateral branching before the plant initiates flower buds in response to shorter day lengths.
Winter Preparation
To prepare for winter, wait until the foliage has died back after the first few hard frosts. Then, apply a four-to-six-inch layer of loose mulch, such as straw or pine needles, over the plant crown. This insulation helps regulate soil temperature and protects the shallow roots from repeated freezing and thawing, a process known as frost heave.