Garden mums (Chrysanthemum spp.) are herbaceous perennials in the daisy family and are stalwarts of the flowering autumn garden. When garden centers sell blooming potted mums in the fall, they are usually used as annuals and discarded when the blooms fade. And when gardeners try to transplant these mums into the ground late in the season, chances are they won't make it through winter and become perennial.
However, there are varieties that are truly perennial in most climates when planted in the early spring or the fall several weeks before frost. Their hardiness, plus their ability to be pinched back during the summer so they won't bloom until fall, make these jewel-toned beauties a welcome splash in the garden at a time when most summer flowers have faded. These plants grow fast, and you should have flowers in the first growing season. Bloom times vary with variety and climate from early September through mid-October.
|Botanical Name||Chrysanthemum spp.|
|Common Name||Garden mum, garden chrysanthemum, hardy chrysanthemum, hardy mum, mum|
|Plant Type||Herbaceous perennial flower|
|Mature Size||4 to 36 inches tall and 12 to 36 inches wide (size varies depending on the variety)|
|Sun Exposure||Full sun|
|Soil Type||Rich, humusy, moist, well-draining|
|Soil pH||6.5 to 6.7|
|Bloom Time||September to frost|
|Flower Color||Yellow, white, red, purple, some bicolors|
|Hardiness Zones||3 to 9|
|Native Area||Asia and northeast Europe|
How to Grow Hardy Chrysanthemums
Plant mums in fertile, moist, well-draining soil as soon as the soil warms in the spring. Mums generally prefer full sun, but they will tolerate some light shade. From late spring to mid-summer, pinch back the tips and flower buds on all shoots to make the plant bushier and prepare it for a dramatic fall show. For optimal blooming, the plants should be fertilized regularly throughout the growing season.
After the blooms fade, cut the plants down to about 6 inches, and cover them with straw or another dry mulch to protect the roots over winter. Established plants should be lifted and divided every two to three years.
Mums can make a wonderful impact in containers. But when planted in mixed borders, they will end your garden season with a bang. That's especially true when you pair them with other late-season bloomers, such as sedum, goldenrod, Russian sage, asters, and gaillardia.
Furthermore, because mums flower so late in the season, they are nondescript, though not unattractive, in the garden until blooming time. Thus, they are best planted next to early bloomers. As the spring flowers die back, the mums will fill in and hide their unattractive fading foliage.
Mums thrive in full sun but can handle a bit of shade. Generally, flowering will be most profuse if they are grown in full sun. However, in warm climates the plants often appreciate some shade during the heat of the afternoon. Mums set buds in response to day length, so avoid confusing them by planting where they might be exposed to bright nighttime light from a patio or window.
These flowers can handle several soil types, but they do best in rich soil that has sharp drainage. Poor soil drainage will cause the plants to rot.
Mums require a lot of water. Give them 1 inch per week during the early growing season, and then increase this to two or three times a week as the flower buds mature and the flowers begin to open.
Temperature and Humidity
Mums do best in moderate climate conditions. Extreme heat can cause the plants to struggle. And regions with hard winter freezing can see the plants succumb to cold unless they are covered with deep mulch. The plants prefer some humidity, though make sure they have good air circulation if the humidity is high to prevent rot or disease.
These are heavy feeders. Give them a time-release fertilizer in the spring, and then feed monthly with a water-soluble balanced fertilizer until late summer. As flower buds begin to develop, increase the feeding to twice a month. Compost mixed into the soil will also benefit mums.
Propagating Hardy Chrysanthemums
The easiest way to propagate garden mums is by rooting stem cuttings. Pinch off a 6-inch stem from a healthy mum plant. Make sure the cutting has at least four leaves. Then, cut the bottom of the stem about 1/2 inch below the lowest leaf node. Carefully pull off the leaves from the lower half of the cutting.
Bury the cutting in moist perlite, so the bare portion of the stem is covered. One or two leaf nodes should be under the planting medium. Set the cutting in a warm room in bright, indirect light. Keep the perlite slightly moist at all times. But avoid overwatering, which can cause the cutting to rot. You'll know the cutting has rooted by gently tugging on it and feeling some resistance. Then, you can transplant it into a container with potting mix. In four to six weeks, it should be ready to transplant into the garden.
Growing Hardy Chrysanthemums in Containers
Garden mums are often purchased already flowering in containers. These should be watered daily. Weekly feeding with a diluted water-soluble fertilizer can prolong the blooming.
If you want to transplant container mums to the garden after the blooms are finished, be aware that these plants are often quite tall and rangy varieties that have been treated to retard their growth and keep them bushy. They often revert to being leggy plants if they come back in the spring.
Common Pests and Diseases
Mums can suffer damage from aphids, thrips, and spider mites. Some signs include leaf and stem damage, webbing on the plants, and visible insects. Common diseases include botrytis, leaf spots, rust, powdery mildew, stem and root rots, verticillium wilt, aster yellows, and viruses. If your plant has visible damage or just seems to be failing to thrive, a disease might be the culprit. Leaf spots and powdery mildew are rarely fatal, but plants with other diseases should be removed and destroyed.
Varieties of Hardy Chrysanthemums
Many varieties of garden mums have been bred. The original species are often unclear, but horticulturalists generally categorize garden mums by flower shape:
- Anemone: One or more rows of petals with a cushion-like center
- Pompom: Familiar globular shape
- Regular incurve: Petals curve up and in, forming a sphere
- Single or daisy: Looks like its cousin, the daisy
- Spider: Long, curled petals droop down and give a spider-like look
There are also shorter, mounding varieties of mums generally grouped as "cushion" mums.
You will rarely find named mums in garden centers. To obtain the exceptional varieties or exhibition mums, you will need to start from seed or order from a nursery or specialty mail-order company.
- Chrysanthemum ‘Clara Curtis’ is an offering from the Rubellum Group of hybrids. It is a long-lasting variety that blooms relatively early in the season with single or semi-double pink flowers.
- Chrysanthemum ‘Mary Stoker’ is also from the Rubellum Group. It is an early season mum with apricot yellow, single-flower heads.
- Chrysanthemum ‘Apricot Moneymaker’ is a mid-season, anemone-style mum with bronze petals.