Chrysanthemums, or “mums” for short, are perennial flowering shrubs that are sometimes grown as annuals. They originate in China, Japan, and Europe. These longtime garden favorites bloom proliferously despite cold, wet climates. They’re often available as summer wanes late in the growing season.
The genus Chrysanthemum was recently reclassified, and lots of old chrysanthemums now fall into new genera. Shasta daisies, for example, were Chrysanthemum maximum, while they’re now Leucanthemum x superbum. Florists, hardy, and perennial chrysanthemums are still in the genus, and they’re the three types we’ll discuss.
All chrysanthemums sprout dozens of flowers on slender stems with divided foliage throughout. Florist mums sprout off single stems, and the blossoms are typically as big as dahlias, or larger! Garden mums are the hardy type best for outdoor growing, and perennial mums are also cold hardy species.
Let’s find out which kind of chrysanthemums you have, and whether or not they are annual or perennial.
The Short Answer
Chrysanthemums are hardy or frost-tender herbaceous perennials. Growers use them as annuals since they’re frost tolerant and widely available during winter, but they’ll survive perennially when they receive a head start on the growing season.
Some species are hardier than others, while most thrive outdoors between USDA hardiness zones 5 through 9. Keep reading to discover how to care for mums in colder zones.
The Long Answer
Whether chrysanthemums survive the winter depends on the species, their growing culture, and your local climate. First, analyze what conditions you have and what mum you’re growing. Then, you’ll be able to make the best decision for its continued survival.
Garden Mums
Garden mums are the most common chrysanthemum type in the Chrysanthemum x morifolium hybrid species, previously Dendranthema x grandiflorum. These are hardy chrysanthemums that cover themselves with flowers in early fall. They have one of the widest ranges of colors, shapes, and flower structures out of any cultivated ornamental plant species.
These varieties are hardy between hardiness zones 5 to 9. They grow underground stolons, or creeping roots, that help specimens survive light freezes. They’re the same types as florist mums, except they’re left to grow without pruning interference.
If you bought these flowers in pots this fall, they likely won’t survive the winter outdoors. They need about two months of frost-free mild weather in the ground to put down enough roots. Transplant them late, and freezing temperatures shock your plants to death.
Keep them inside this winter, and they’ll be able to survive next year. You can do this with in-ground mums as well, as long as you give them enough time to ease into their containers for winter.
Florist Mums
Florist mums are also in the hybrid species Chrysanthemum x morifolium, although they receive completely different treatments during their young lives. Florist mums undergo rigorous pruning, pinching, and root disturbance to create larger-than-normal flowers on tall stalks. They’ll never occur naturally, but they sure are pretty!
Although florist chrysanthemums are the same type as garden ones (technically perennial), they’re considerably less cold-hardy and often grown as annuals. Their rigorous pruning and maintenance prevent them from growing ample stolons, and they’ll die if you transplant them outdoors under cool weather. They’re also selected from non or low-stolon-producing species that are frost tender.
Keep florist mums indoors until warm temperatures arrive after your last frost date. Then, transplant your plants outdoors into soil high in organic matter. Most florist mums survive mild winters when you plant them this way, although they will tucker out if temperatures drop lower than normal. Therefore, they aren’t as suited to lower zones. Fear not, since we’ll learn more care tips for overwintering chrysanthemums below.
Perennial Mums
Other chrysanthemums exist that thrive perennially in warm or cold winter zones. There used to be many more, but recent reclassifications have put the others into new genera like Dendranthema, Argyranthemum, Leucanthemum, Glebionis, and Tanacetum. Two existing perennials work well for freezing gardens: Chrysanthemum species in the Rubellum Group and Chrysanthemum zawadskii.
Rubellum group perennials are like florist and garden varieties, sprouting two to three-inch wide blossoms on two-foot-tall stems. They sprout pink, yellow, or apricot blooms and are cold-hardy from zones 4 through 8. Use them for small pockets of color in borders, pollinator gardens, or raised beds.
The other type is more of a rock garden species than an ornamental one, as it thrives with lots of sunlight and free-draining soil. This perennial originates from Japan and is shorter than other types, reaching no higher than a foot to a foot and a half tall. They bloom pink, red, or white blossoms with yellow centers in late fall, and they’re also hardy from zones 5 through 9.
How To Overwinter
You have a few options for taking care of your chrysanthemums throughout the winter. For those that aren’t root hardy, let them bloom outdoors until they die, and then toss the dead plant into the compost. Alternatively, overwinter them indoors or in a greenhouse to keep them blooming year after year.
You may transplant hardy and perennial varieties outdoors into your garden if it’s at least two months before your first fall frost date. Dig a hole as deep as the rootball and twice as wide, and place your shrub in the hole. Backfill with soil, and add a healthy layer of compost or organic mulch on top of the root zone. Your hardy mum will put down ample roots and stolons to help it survive winter.
If it’s past this time, wait until spring to transplant outdoors. They’ll be at risk during frosty weather and prefer having a vacation indoors in the warmth of your home. They also appreciate greenhouse and hoop house conditions, so if you have season extension, use it for your tender varieties. Place them in a window with bright indirect light all day or direct sunlight for three to six hours during the winter.
Taking Cuttings
With chrysanthemums surviving in the ground, you’ll have optimal conditions for multiplying them with cuttings. As new growth sprouts from spring until early summer, take two to three-inch cuttings from the ends of the shoots. Strip them off their lower leaves and place them in a rooting culture like perlite, vermiculite, or potting soil down to the first set of leaves. Keep them moist under dappled shade, and they’ll sprout roots in three to four weeks.
Once your cuttings develop one-and-a-half to two-inch roots, they’re ready to populate your yard. Plant them in containers, raised beds, or borders for late summer through early winter flower power. Cuttings are a surefire way to replicate existing varieties, meaning you can turn one plant into dozens in a year.
Cuttings don’t appreciate being root-bound, so transplant them as they outgrow their containers. The more roots they grow, the more flowers they’ll bloom. 5” cube pots work well for cuttings, and one to three-gallon pots are great for maturing specimens.
Growing Outdoors
Chrysanthemums need lots of organic matter in their soil, with air, moisture, and fungal activity. Mix compost into their soil at the time of planting and add regularly add thick layers from spring through winter. The best time to transplant them outdoors is spring—wait if you can for a warm weather planting.
Organic fertilizer helps chrysanthemums form more blooms for a spectacular display. Apply a regular dose according to the package’s directions two to three times during the growing season. Use low nitrogen fertilizer during flowering, as excess nitrogen causes leaves at the expense of blooms.
For florist mums, you’ll need to pinch your plants, so they have one or two flowers on a single stem. Identify blooms on lateral shoots and pinch them off as they form. You’ll grow large flowers bigger than any of your neighbors! Other mums require less or no pinching unless you’d like to encourage larger blossoms.
