In late summer, when other plants are calling it quits, mums hit their stride. Like poinsettias, they are photoperiodic, meaning they rely on specific amounts of light to send the signal that it's time to start putting on a show. On average, garden mums will not start to set buds until the nights are about 10 hours long. Blooms follow in 6 to 10 weeks. Cool temperatures don't bother mums, either. In fact, chilly weather intensifies colors and keeps blossoms looking fresh until a hard, killing frost drops the curtain on the gardening year. If you choose early-, mid-, and late-blooming varieties, you will enjoy a full seven weeks of bloom—a brilliant last act for any landscape.
When selecting varieties, you have a wide range of types to pick from (as you can see in the photos on these pages): decorative, daisy, and low-growing cushion mums as well as early-blooming anemones, quills, and spiders. The new European-style Prophets Series, from Yoder Brothers, an Ohio-based wholesale breeder and nursery, boasts more than 100 blossoms per plant. These sturdy-stemmed, ball-shaped beauties were inspired by varieties beloved in Belgium, where All Saints' Day is celebrated each November 1 with lavish mum displays.
Though technically perennials, mums are often grown as annuals, owing to shallow root systems inclined to heave right out of the ground during winter's freeze-thaw cycles. If you live where winter can be frigid (USDA Plant Hardiness Zones 3 through 6), go with early-blooming varieties—they are more likely to come back in subsequent years. Those of you who live south of Zone 6, on the other hand, can push the envelope, opting for varieties that need more time to reach their full potential. When winter looms, apply a mulch of crisscrossed evergreen boughs to help plants make it through the cold weather ahead.
Several years ago, horticulturists at the University of Minnesota developed a new chrysanthemum hybrid described by perennial breeder Neil Anderson, Ph.D., as a "hardy shrub mum." Dubbed the My Favorite Series, the robust plants were touted as reliably perennial as far north as Zone 3b. They have been hard to find in the past couple of years but returned to the market this year under a new name, the Mammoth Series. Seven colors are currently being sold at nurseries, with more varieties scheduled for release in 2007. True to their new designation, these oversize mums can measure 2 to 3 feet tall and 4 to 5 feet across by their third season, with a massive canopy of flowers—up to 5,000 per plant. Monarch butterflies adore these shrubby wonders.
Finally, to further increase the odds that your chrysanthemums will survive winter, consider planting them in spring as opposed to late summer, to give root systems ample time to become established.
- Soil. While mums thrive in just about any soil type, they do benefit from generous helpings of homemade compost. Dig in a spadeful at planting time and topdress with more. Soil must be well drained, however, or the plants will rot.
- Sunshine. Mums planted in full sun bloom more profusely than those in partial shade. An optimal site receives 6 to 8 hours of direct light.
- Water. Shallow-rooted mums dry out quickly. Be sure to water consistently, especially during dry spells and in fall, when plants are storing up energy for winter survival.
- Pinching back. If you don't like the leggy look (who does?), early in the season remove the tips of stems to encourage branching. Repeat the process every two weeks until mid-July. Mums purchased as annuals in late summer do not require this treatment.
Creating new plants from your favorite mums is easy, says Galen Goss, executive director of the National Chrysanthemum Society. Simply snip off a 4-inch stem (be sure it has leaves on it) and put it in a pot with a soilless medium, such as vermiculite. Keep it moist and outdoors, in a bright spot. After a couple of weeks, repot the cutting (which has sprouted roots) to a small container (foam coffee cups with drainage holes work well) filled with potting soil. Fertilize once a week. Two to three weeks later, transplant it into the garden, and keep fertilizing. You'll enjoy flowers that very autumn!
A Mum for Every Purpose
- Use shorter cushion mums to carpet a slope. Foot-tall mounds of lush foliage make an attractive groundcover until late summer, when colorful flower heads steal the show.
- Start a nursery bed where you can grow your own mums from cuttings. In late summer, transfer the ready-to-bloom plants into the garden, to take the place of tired-looking annuals.
- When a killing frost is predicted, pot up your mums and bring them indoors to adorn the Thanksgiving table.
- Plant taller varieties for use as cut flowers. After cutting, split the stem ends so they can take up water more efficiently.
5 More Mums You'll Love
- To stop traffic: The spider mum 'Senkyo Kenshin' stands 3 1⁄2 feet tall. It blooms midseason, with about 27 striking, reddish-bronze blossoms per plant.
- For brilliant color: 'Jessica' has joyful, bright yellow blossoms. This midseason decorative mum is from the Prophets Series.
- Does double duty: An old favorite, 'French Vanilla' has 3 1⁄2- inch white flowers. Grow in a mixed border or cutting garden.
- Takes the cold: 'Minnautumn' is an extremely cold-hardy—to Zone 3—decorative cushion mum. It's only 15 inches tall, with vivid orange-red flowers.
- For the vase: 'Carrousel', a purple quill mum, is an elegant cut flower. Huge blossoms measure up to 4 inches across.