Chrysanthemums, commonly known as mums, transform landscapes into vibrant displays of color as the gardening season turns toward autumn. These plants are popular for their late-season blooms, but many gardeners are confused about whether the plants they purchase are temporary decorations or permanent garden additions. Understanding the different varieties is the first step toward successful cultivation. This guide provides practical instruction on planting and long-term care to help ensure your mums thrive.
Determining Planting Season and Mum Type
The success of a chrysanthemum as a returning perennial depends on its type and planting time. Varieties fall into two main categories: Florist Mums and Hardy Garden Mums. Florist mums are bred for abundant bloom and are often treated as annuals, lacking the robust root system needed to survive winter in colder climates. Hardy garden mums are perennial varieties that develop underground shoots, called stolons, allowing them to establish and return year after year in appropriate hardiness zones.
The ideal time to plant hardy mums is in the spring, after the last frost, which provides the entire growing season for root establishment. Root development is prioritized during this period, fortifying the plant against the stresses of winter. Fall is the time when most chrysanthemums are purchased in full bloom for immediate visual impact. When planting in autumn, it is recommended to do so at least six weeks before the first hard frost to allow some root anchorage, though this timing often proves too late for reliable perennial survival in northern zones.
Preparing the Soil and Selecting the Location
Chrysanthemums require a planting site that receives full sun, meaning a minimum of six hours of direct sunlight each day for healthy growth and maximum flower production. Plants situated in less light tend to become spindly and produce fewer flowers. Avoid planting near artificial light sources, such as street or porch lights, as this can interfere with the plant’s light response, triggering flower bud formation.
The soil composition is important, as mums are susceptible to root rot in waterlogged conditions. They require rich, well-drained soil, ideally with a slightly acidic to neutral pH (6.0 to 8.0). If the garden plot contains heavy clay, incorporate a two- to three-inch layer of compost or organic matter into the top six inches of soil to improve drainage and fertility. Good air circulation around the plants helps prevent fungal diseases, so select an open location away from dense shrubbery.
Step-by-Step Guide to Planting Mums
Before planting, ensure the chrysanthemum is well-hydrated by watering the container thoroughly. Carefully remove the plant from its nursery pot. If the roots are tightly matted or circling (root-bound), gently loosen them with your fingers or a small tool. This manipulation encourages the roots to grow outward into the surrounding garden soil.
Dig a hole that is two to three times wider than the root ball, but only as deep as the root ball itself. Place the plant so the top of the root ball is level with the surrounding soil line; this prevents water from pooling around the stem and causing rot. Backfill the hole with the amended soil, lightly firming it to eliminate air pockets. Space multiple mums approximately 18 to 30 inches apart to allow for mature size and proper air circulation.
Ensuring Successful Establishment and Growth
Immediately after planting, provide a deep watering to settle the soil around the roots and ensure good contact. Maintaining consistent moisture is important during the first few weeks as the plant establishes itself. Because mums have a shallow root system, they can dry out quickly, necessitating regular monitoring, especially in warm weather.
For hardy mums planted in the spring, pinching back new growth encourages bushiness and a denser habit. When new shoots reach six to eight inches tall, remove the top inch of the stem, leaving several sets of leaves. Repeat this pinching process every few weeks until early to mid-summer, stopping around the first week of July to allow flower buds to form for the autumn bloom.
Fertilization should be done lightly with a balanced formula throughout the growing season, but discontinue it once flower buds begin to appear. For hardy varieties intended to overwinter, cut the stems back to about eight inches after the foliage has died down. Apply a thick layer of loose, organic mulch (such as straw or evergreen boughs) around the base of the plant after the ground has frozen. This provides insulation and protection for the crown during the coldest months.