Garden mums (Chystanthemum spp.) are herbaceous perennials in the daisy family and are stalwarts of the flowering autumn garden. When garden centers sell large numbers of blooming potted mums in fall, they are usually used as annuals and discarded when the blooms finally fade. When gardeners transplant these mums into the ground late in the season, chances are good they won't over-winter and be perennial. However, there are varieties that are truly perennial in most climates. 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 begun to fade. Bloom times vary with variety and climate, from early September through mid-October.
- Botanical Name: Chrysanthemum spp.
- Common Name: Garden mums, garden chrysanthemums, mums
- Plant Type: Herbaceous perennial flower
- Mature Size: 4 to 36 inches tall, 12 to 36 inches wide; size varies depending on the variety.
- Sun Exposure: Full sun
- Soil Type: Humusy, fertile soil that is moist but well-drained
- Soil pH: 6.5 to 6.7
- Bloom Time: September to frost
- Flower Color: Various shades of yellow, white, red, purple; some bicolors
- Hardiness Zones: 3 to 9
- Native Area: Native to Asia and northeast Europe; most species come from eastern Asia.
Types of Chrysanthemum
Hundreds, if not thousands, of different 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.
Since mums bloom so late in the season, they are non-descript, though not unattractive, in the border until blooming time. They are best planted next to early bloomers. As these spring blooming flowers fade, the mums will fill in and hide their unattractive fading foliage.
Mums make a wonderful impact in containers, but when planted in mixed borders, they will end your garden season with a bang when paired with other late season bloomers such as sedum, goldenrod, Russian sage, asters, gaillardia and the changing foliage of ornamental grasses.
How to Grow Hardy Chrysanthemums
Plant mums in fertile, moist, well-drained soil, as the soil warms in the spring. Mums generally prefer full sun, but they will tolerate some light shade and may actually prefer some shelter in very warm climates. From late spring to mid-summer (about July 4), pinch back the tips and flower buds on all shoots to make the plant bushier and prepare it for a dramatic fall show. For best bloom, the plants should be fertilized regularly through 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 thrive in full sun but will tolerate some light shade. Generally, flowering will be most profuse if they are grown in full sun, but in warmer climates, the plants may 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 may be exposed to bright nighttime light from a patio or window.
Plant mums in rich fertile soil. Ideal soils are consistently moist, but also well-drained.
Mums require a lot of water. Give them a full 1 inch per week during the early growing season, 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 may cause the plants to struggle, and regions with hard winter freezing may see plants succumb to cold unless they are covered with deep mulch.
These are heavy feeders. Give them a time-release fertilizer in the spring, 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.
Propagating Garden Mums
The easiest way to propagate garden mums is by rooting stem cuttings.
- Pinch off a 6-inch long stem from a healthy mum plant. Make sure the cutting has at least four leaves.
- 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 into the moist perlite so the bare portion of the stem is covered. One or two leaf nodes should be under the planting medium.
- Set the cuttings in a warm room, in bright, indirect light.
- Keep the perlite slightly moist at all times. Avoid overwatering, which can cause the cutting to rot.
- Periodically check the cuttings for roots. This can be done by carefully lifting the cutting up using a spoon. When the roots are at least 1 inch long, transplant it into a potting container filled with good commercial potting soil.
- Set the new seeding in a sunny location to continue growing. In 4 to 6 weeks, it will be ready to transplant into the garden.
Varieties of Garden Mums
You will rarely find named mums in garden centers. To obtain the exceptional varieties or exhibition mums, you will need to order from a nursery, a specialty mail-order company, or start from seed.
- 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.
Growing in Containers
Garden mums are often purchased already flowering in containers. These should be watered daily. Weekly feeding with a diluted water-soluble fertilizer may prolong the blooming.
If you want to transplant these 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 very tall plants when they come back in the spring.
Common Pests and Diseases
Mums can suffer damage from aphids, thrips, and spider mites. Common diseases include botrytis, leaf spots, rust, powdery mildew, stem and root rots, verticillium wilt, aster yellows, and viruses. Leaf spots and powdery mildew are rarely fatal, but plants with other diseases should be removed and destroyed.