Consider Garden Mums for Fall Color

By B. Rosie Lerner
Extension Consumer Horticulture Specialist

As much of the garden fades into the fall, you can bring out a rainbow of color with garden mums. Colors include many shades of yellow, orange, red, purple, bronze, pink, and white. The flowers themselves come in many different forms, from spider types with long, narrow petals to cushion types that have wider, more compact flowers.

Long known as Chrysanthemum, botanists have recently reclassified the popular garden mum as Dendranthema x grandiflora. The mum is thought to have been cultivated in China more than 2,000 years ago, and many botanists believe it probably had its origin there. The Japanese adopted the mum with great enthusiasm and have devoted centuries to its culture, hybridization and improvement. It has been the national flower of Japan for several hundred years. Here in the United States, the mum has become a popular garden plant and a standard for the commercial florist industry.

Not all mums are hardy in the garden - many florists' mums can be planted in the garden to be enjoyed for that growing season, but do not expect a comeback in subsequent years. When buying for the garden, get plants from a garden center or nursery that carries plants grown for the outdoors.

The best planting time is late spring, but fall planting can be successful with a little extra attention to watering and winter protection. Choose a sunny, well-drained location with good air circulation for optimum growth and disease resistance.

Mum plants flower in response to both day length and temperature. Most cultivars begin to develop flower buds when days are less than 12 hours long, then generally continue to flower for a period of six to eight weeks. Some cultivars are not as responsive to day length and may begin flower development early in the summer in response to heat. Catalogs usually list cultivars as early, midseason or late types.

Plants purchased this summer and fall likely have been groomed to have a compact habit loaded with flower buds. In order to recreate that effect next year, you'll need to do a little pinching in the spring and early summer to promote branching. To pinch, simply remove about .5 inch to 1 inch of stem back to a leaf. The first pinching should be done when the plants are about 6 inches tall (about mid-June) to induce lateral branches. As soon as these lateral branches become 6 inches to 8 inches long (about mid-July), they, in turn, should have their tips removed to induce more branching. This procedure may seem drastic, but the result will be bushy, well-shaped, flowering plants. After the July pinch, let the plants' foliage take its course; late pinching can reduce the number of flower buds.

Garden mums are generally hardy throughout Indiana, but many plants can be lost following extreme winters. Applying winter protection in the form of a mulch can be helpful, especially for newly planted mums. The purpose of the mulch is to keep the soil cold after it has become frozen, eliminating alternate freezing and thawing and the resulting soil heaving. The best time to apply a mulch is late November or early December after two or three episodes of temperatures below 20 F. Winter injury is most common in poorly drained soils.

For more information about consumer horticulture in Indiana, contact:

Rosie Lerner
Extension Consumer Horticulture Specialist/Master Gardener State Coordinator
Purdue University
1165 Horticulture Building
West Lafayette IN 47907-1165

Voice: 765-494-1296
FAX: 765-494-0391
Internet: brl@hort.purdue.edu

Last updated: 10 April 2006
Questions about this page should be sent to homehort@purdue.edu