Growing Chrysanthemums In the Garden

MP3 (3:49 minutes, September 24, 2015)

When most annuals and perennials are winding down for the season, chrysanthemums reach their peak. Mums offer gardeners a wide range of colors and flower forms. They require moderate levels of maintenance. Chrysanthemums have been popular in the United States only during the past 75-80 years. The plant is native to China.

Chrysanthemums can be planted in the spring or fall. However, spring plantings are much more likely to survive the winter. Spring plantings can be made anytime from late April through May. Oftentimes garden mums grown for spring sales have been forced into bloom. After flowers fade, prune the plants back to one-third to one-half their flowering height and they will bloom again in the fall. If you purchase garden chrysanthemums late in the summer for fall display, plant them early, at least six weeks before a killing frost so that the plants can become established. Choose an area that receives full sun and is several feet away from street lights or other night lights. Exposing the plants to light during the night may inhibit flower formation. Chrysanthemums grow well in most soils, however, good drainage is essential. Avoid poorly drained, wet spots. Before planting, work the soil to a depth of 8 to 12 inches and incorporate 2 to 4 inches of organic matter, such as decomposed manure, peat moss or compost. Set young plants 18-24 inches apart to give them room to develop into full mound-shaped plants.

Keep chrysanthemums well-watered throughout the season. Fertilize spring planted mums once a month through July with water soluble plant food. No fertilization is necessary for fall-planted mums.

Because garden mums are hardier than florist mums, they are often called “hardy” mums. Unfortunately, their hardiness is not always reliable and cultivars vary in their degree of winter hardiness. Chrysanthemums have a shallow root system and are especially affected by severe cold, repeated cycles of freezing and thawing, wet heavy soil, and lack of snow cover.

Here are a few things you can do to increase the chances that your mums will survive the winter.

  • Select early-flowering cultivars that are known to be hardy for your area.
  • Avoid planting mums in areas subject to cold, dry north winds. Stop fertilizing the plants by the end of July to discourage late season growth.
  • Don’t prune the plants back in the fall. Research has found that garden mums survive the winter better if the old foliage is left standing through the winter.
  • Mulching is the best insurance for overwintering mums. It helps keep the soil uniformly cold after it has become frozen, thus eliminating the alternate freezing-thawing cycle and the resulting soil heaving. Apply the mulching material, such as 2-4 inches of straw, in late November or early December when temperatures dip to 20-25 degrees and the soil surface freezes. Leaves are less suitable as a mulch because they tend to pack solid when wet. Covering garden mums when an early hard frost is forecast will extend the blooming period later into the fall.

Source: Reiman Gardens, University of Iowa Extension