Plastic nursery pots filled with perfectly pinched mounds of chrysanthemums are starting to appear at local garden centers, farmers markets, and grocery stores. This seasonal influx of mums is a sure sign that fall has arrived. After the blooms have faded, most potted mums end up in the compost or trash. But by following a few simple steps, it is possible to overwinter these plants and enjoy additional seasons of blooms.
Mums, the magenta blooms pictured above, are a popular addition to fall garden displays. Here, they appear in the William T. Kemper Center’s demonstration gardens. Photo by Sundos Schneider.
Where Do Potted Mums Come From?
The vast majority of mums sold in the fall are hybrid chrysanthemums, commonly called garden mums or hardy mums. Garden mums are hardy in Zones 5-9 and can be grown as perennials in the St. Louis area. They are typically grown at large scales in greenhouses from cuttings received in bulk in the spring. Nurseries or garden shops that do not have the space to grow on their own mums will purchase finished plants that are ready to sell from growers.
Garden mums are available in a wide variety of shades, including pinks, purples, yellows, oranges, and reds. Pictured above, Chrysanthemum ‘Copper Coin Bronze’ provides a fiery burst of color. Photo by Tom Incrocci.
Caring for Your Potted Mums
Here are a few steps to follow if you want to add garden mums purchased in the fall to your landscape:
- Make sure you have a good location for them to grow. Garden mums grow best in full sun with soil that is well-draining but stays evenly moist.
- Plant your mums immediately into their new home after purchase. The sooner the plants are able to start establishing their root system, the more likely they are to survive the winter. Do not wait to plant until after the flowers have faded.
- Keep the plants watered so they do not experience any drought stress.
- When the blooms have faded and the stems have started to die back, cut the stems back to 6 inches and apply a thick layer of mulch. Wood chips, leaves, or evergreen boughs can all be used. The mulch will help to insulate the dormant plants from large temperature swings during the winter and can also help to prevent frost heaving. Frost heaving occurs when the soil around newly transplanted or shallow-rooted perennials experiences repeated cycles of freezing and thawing, causing the plant to shift and rise out of the soil. This damages the roots and exposes them to colder temperatures.
- Gently remove the mulch in spring.
Once transferred from their pots into the ground, mums are often able to survive for multiple seasons with a little extra care. Photo by Sundos Schneider.
How to Save Your Mums for Seasons to Come
To keep your mums blooming year after year:
- Apply mulch at the end of every fall.
- Fertilize in the spring with an all-purpose, slow-release fertilizer.
- Keep the stems pinched back as needed to promote bushy, compact growth. Stop pinching in July to allow flower buds to form.
- Divide overgrown clumps every few years in the spring or fall.
Hardy Chrysanthemum Varieties to Consider
There are many variables outside of the gardener’s control that will affect the chances of garden mums surviving the winter, and, even with the most meticulous care, your mums might not come back. If you are looking for the best chances of success, consider purchasing and planting hardy chrysanthemums in the spring and choosing cultivars that have proven garden performance. Here are two recommendations from the Missouri Botanical Garden’s Kemper Center for Home Gardening:
Chrysanthemum ‘Hillside Sheffield Pink’
Chrysanthemum ‘Hillside Sheffield Pink’ is a great candidate for a gardener looking for a mum that will return year after year. Photo by Kristina DeYong.
This is the most popular mum for mixed border plantings. ‘Hillside Sheffield Pink” forms blanket of pale, apricot-pink, single blooms that cover the upright stems from September through to frost. Mature plants will reach 2–3 feet tall with a similar spread and a mounding growth habit. This plant is sometimes sold under the names ‘Sheffield Pink’ or ‘Single Apricot’.
Chrysanthemum ‘Matchsticks’ sports color-changing petals and is usually avoided by rabbits and deer.
The unique, spoon-shaped petals of this compact garden mum cultivar turn from shades of golden yellow to ruby red as the weather cools. Mature plants will reach 1.5-2 feet tall with a similar spread.
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Feature photo by Tom Incrocci