Chrysanthemums, affectionately known as mums, deliver an unmistakable burst of color when many other flowers begin to fade. Treating these iconic autumn blooms as annuals is the simplest route, yet with a little effort, you can overwinter them successfully and enjoy their return year after year. Learning how to store mums for the winter focuses on protecting the crown and roots from freezing damage while managing moisture levels. The process varies slightly depending on whether your plants are garden specimens in the ground or potted specimens on a patio, but the underlying principles remain consistent.
Preparing Mums for the Cold Months
As the summer heat fades and nights turn crisp, the work of winter preparation begins. Healthy plants enter dormancy with stored energy, so avoiding late-season fertilizer is critical. Stop feeding your mums about six weeks before your first expected frost to encourage the natural hardening process. This slowdown helps the plant shift its energy from foliage to the crown, which is the crucial survival point during cold weather.
Pruning and Cleanup
Once the foliage has been nipped by the first light frost or appears damaged, it is time to prune. Cut the stems down to about four to six inches above the soil line, which helps prevent diseases from taking hold over the winter. Remove any remaining leaves, fallen petals, and debris from the surrounding soil to eliminate pests and fungal spores that could linger until spring. Clean up around the base of the plant to create a healthier environment when growth resumes.
Storing Potted Mums
If your mums are growing in containers, you have the most flexibility in how you store them for the winter. The biggest threat to potted specimens is freezing soil, which expands and can heave roots right out of the ground or crack the pot. The goal is to move them to a location where the temperature stays consistently just above freezing.
Move the pots into a cool garage, unheated sunroom, or a sheltered porch where temperatures hover between 30°F and 50°F.
Check the moisture of the soil regularly; it should be barely damp, never soggy or bone dry, to prevent root rot or desiccation.
Group the pots together to create a microclimate that buffers them against extreme temperature swings.
Overwintering Mums in the Ground
Garden-planted mums require a different approach, focusing on insulation rather than relocation. In regions with mild winters, a simple layer of protection might be sufficient. In harsher climates, you need to simulate the natural insulation that snow would usually provide.
After the ground freezes, apply a thick layer of mulch, such as straw or shredded leaves, around the base of the plant.
Avoid piling the mulch directly against the stems, as this can trap moisture and cause rot.
Create a mulch ring or "donut" shape that extends a few inches beyond the plant's outer edge to protect the root zone.
Dividing for Health and Longevity
Over time, garden mums can become crowded, with the center of the plant dying out while the edges remain vigorous. Dividing the clump every two or three years—in early spring or late summer—reinvigorates the plant and provides you with new stock. Carefully lift the entire root ball, separate healthy sections with a sharp knife, and replant immediately. Dividing before winter ensures the new divisions have ample time to establish roots before the ground freezes, making them more resilient to storage stress.
