Chrysanthemums, often simply called mums, are herbaceous perennials that can return to your garden year after year with proper care. The top growth dies back in winter, while the root system remains alive to sprout anew in spring. The ability of the Chrysanthemum genus to survive depends on planting a hardy variety, known as garden mums, and ensuring they have sufficient time to establish a robust root system before the first hard freeze.
Optimal Timing and Location for Planting Mums
The timing of planting directly affects the likelihood of a mum surviving its first winter and returning as a perennial. For long-term establishment, planting in the spring is significantly better than planting in the fall, as it allows the shallow, fibrous root system months to develop before the ground freezes. If you purchase plants in autumn for immediate color, they should be placed in the ground at least six weeks prior to the first expected killing frost in your region.
Mums require full sun exposure to thrive and produce abundant blooms, necessitating a location that receives a minimum of six hours of direct sunlight daily. The soil must be well-drained; chrysanthemums will quickly suffer and die in soggy conditions where water pools or sits. Incorporating organic material, such as compost or peat moss, before planting helps improve both drainage and soil fertility.
Step-by-Step Guide to Planting Mums
Once an appropriate, sunny location with well-draining soil has been selected, the physical planting process must be executed carefully to minimize transplant shock. Begin by digging a hole that is twice as wide as the mum’s root ball but no deeper than the container it came in.
Before placing the plant into the prepared hole, gently remove it from its nursery container and inspect the roots. Mums are often root-bound, meaning the roots are tightly matted and circling the perimeter of the root ball. Use your fingers or a small tool to gently loosen or “tease” these compacted roots so they are encouraged to grow outward.
Place the plant in the hole so that the top of the root ball is level with or slightly above the surrounding soil surface. Backfill the hole with the amended soil, lightly tamping it down to eliminate any large air pockets. Finally, give the newly planted mum a thorough, deep watering immediately after planting to settle the soil around the roots.
Ongoing Care and Ensuring Perennial Return
After the initial planting, the ongoing maintenance routine focuses on encouraging bushiness and protecting the plant through dormancy. During the spring and summer growing season, a process called “pinching” is employed to prevent the plant from becoming tall and leggy. Pinching involves removing the top one-half to one inch of the new stem growth, which breaks the plant’s hormonal dominance and forces it to branch out laterally.
Begin pinching when the plant is about six inches tall and repeat the process every two to four weeks until mid-July to ensure a compact, dense form with many flower buds for the fall. Throughout the blooming period, removing spent, faded flowers, known as deadheading, encourages the plant to focus its energy on producing new blooms rather than setting seed. Proper watering is also necessary, keeping the soil consistently moist but never waterlogged, especially during dry periods.
For successful overwintering and perennial return, resist the urge to cut back the foliage immediately after the fall bloom ends. Leaving the old stems and leaves intact through the winter provides a layer of insulation and helps protect the plant’s crown from harsh weather. Once the ground has frozen solid, apply a heavy layer of loose mulch, approximately three to four inches deep, such as straw or pine needles, over the plant’s base. This mulch insulates the soil to prevent the damaging freeze-thaw cycles that can push the shallow roots out of the ground, a phenomenon known as frost heave.