Chrysanthemums, commonly known as mums, are a genus of flowering plants celebrated for their vibrant, late-season blooms that provide a spectacular burst of color in the fall garden. They extend the gardening season well after most annuals and perennials have faded. Mums come in a diverse range of flower shapes, sizes, and colors, from deep bronzes and reds to bright yellows and whites. Successfully integrating a mum into your landscape requires careful preparation and proper planting technique.
Preparing the Planting Site
The timing of planting depends on the mum type. For perennial “garden mums” to survive winter, plant them in the spring or early summer, allowing at least six weeks for root development before the first hard frost. If planting common potted “florist mums” in the fall, place them in the ground as early as possible to allow for root growth before freezing temperatures arrive.
Select a location that receives a minimum of six hours of direct sunlight daily, which is necessary for robust growth and abundant flowering. A site with a southern or southeastern exposure is often beneficial. The location should also offer protection from strong, persistent winds that can damage the developing stems.
The physical structure of the soil is paramount, as mums are highly susceptible to root rot in waterlogged conditions. The planting site must have excellent drainage. Heavy clay soils must be amended by thoroughly incorporating organic matter, such as compost or aged manure, into the native soil to a depth of at least six inches. This improves aeration and water percolation. Mums prefer a slightly acidic to neutral soil pH, ideally ranging between 6.0 and 6.7.
Step-by-Step Planting Guide
Proper spacing is necessary to ensure good air circulation around the plants, which helps prevent common fungal diseases like powdery mildew. For most garden varieties, space individual plants about 18 to 24 inches apart. This distance allows for the mature spread of the plant and promotes a healthy, bushy habit.
Before planting, gently remove the mum from its container and inspect the root ball. If the roots are tightly packed and circling the soil—a condition known as being root-bound—it is necessary to loosen them. Lightly scoring the sides of the root ball or gently teasing the roots apart encourages outward growth and prevents slow decline.
Dig a planting hole that is two to three times wider than the root ball but only as deep as the container the mum came in. The width allows the loosened roots to spread easily, while the depth ensures the plant is not set too low. Planting too deep can cause water to pool around the base, leading to stem rot.
Set the mum into the hole so the top of the root ball is level with, or slightly above, the surrounding soil line. Backfill the hole with the prepared soil mixture, distributing it evenly around the root ball. Gently firm the soil to eliminate large air pockets that could dry out the roots, but avoid compacting the soil too heavily, which would impede water and oxygen movement.
Ensuring Initial Establishment
Immediately after planting, thoroughly soak the area with water until the soil is saturated to the depth of the root ball. This initial deep watering settles the soil firmly around the roots, eliminating air gaps, and reduces transplant stress. Consistent moisture is necessary for the first week or two until the plant shows visible signs of establishment.
Once the initial water has soaked in, apply a two to three-inch layer of organic mulch, such as shredded bark or compost, around the newly planted mum. Mulch helps maintain a consistent soil temperature and reduces moisture loss through evaporation. Keep the mulch material a few inches away from the plant’s central crown to prevent moisture buildup that could encourage stem rot.
If planting in early spring into less fertile soil, a light application of a balanced, slow-release fertilizer can encourage new root development. If the soil was heavily amended, additional fertilizer may not be immediately needed. Monitor the plant closely for any signs of wilting over the first week and provide supplemental water if the soil begins to dry out a few inches below the surface.