Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
9/13/99
Contacts:
Cindy Haynes, Horticulture Extension, (515) 294-4006,
chaynes@iastate.edu
Elaine Edwards, Extension Communication Systems, (515)
294-5168, eedwards@iastate.edu
Yard and Garden Column for the week beginning Sept. 17
Clearing Up the Confusion over Chrysanthemums
By Cindy Haynes
Extension horticulturist
Iowa State University Extension
The chrysanthemum has long been a symbol of fall in the garden. However, this fall beauty has been bewildering gardeners for many years. Between the ever-changing nomenclature, the enormous variety in flower colors and forms, and the inconsistencies in winter survival, many a good gardener has given up on chrysanthemums. Let me attempt to simplify some of the more confusing aspects of this fall blooming perennial.
The first perplexing aspect of chrysanthemums involves its scientific name. In the 1700s, the name chrysanthemum was given to the plant by the Swedish botanist, Linnaeus. Botanists in the late 1900s reclassified the mum and placed it in the genus Dendranthema. However, recently botanists reversed themselves and placed the plant back in the genus Chrysanthemum. Hopefully this final change will alleviate industry and consumer confusion.
Another disconcerting aspect of mums involves the enormous variety of flower forms and colors. There are two distinct types of mums. One is the garden (often called "hardy") mum and the other is the florist mum. While the florist mum makes a wonderful container plant indoors, it will not overwinter in the garden. The garden mum has the ability to overwinter successfully in the garden because it produces underground stolons that can persist year after year. Florist mums do not produce stolons.
There are several flower forms available as well. These forms include pompon, decorative, cushion, spider, anemone, single, quill and spoon. The pompon flowers are small and globe-like, while the decorative type is large and more open. Single or daisy mums have yellowish centers, while decorative or cushion mums seem to have no centers at all. The anemone-type mum has darker, shorter petals in the center of the bloom. Spoon, quill and spider-type mums have long tubular petals with open spoon-shaped, straight or hooked ends, respectively. There are hardy mums available in most flower forms. Add in the almost unlimited color options with flower forms and selection can easily become overwhelming.
Mum Culture
When planting mums select a sunny site with well-drained soil. Plants should be spaced 18-24 inches apart to allow for sufficient growth. Spring is the best time to plant garden mums. Spring-planted mums establish quickly and are more likely to overwinter. The winter survival rate for mums planted in late summer and fall is much lower because they do not have adequate time to establish in the landscape. Therefore, fall planted mums should be considered an annual in the garden and replanted every year.
To ensure compact, bushy plants with tons of blooms, pinch mums several times in spring and early summer. Pinching requires removing the shoot tips forcing the plant to produce additional shoots along the stem. Stop pinching by July 4 since removal of shoot tips after this date can delay or prevent the formation of flowers.
Mums generally require regular fertilization and irrigation throughout the growing season. Fertilization once a month through July with a complete water-soluble fertilizer should be sufficient. Continued fertilization late in the season can promote succulent growth that may not have sufficient time to acclimate for winter. Water chrysanthemums once a week during dry weather.
Overwintering Strategies
Probably one of the most confusing aspects to growing mums is the unexplained sudden death or loss of plants during the winter. There are several strategies that can aid in overwinter survival of garden mums.
First, be sure to select a garden or "hardy" mum variety, preferably one that flowers early and allows sufficient time to acclimate to our cold temperatures. Second, make sure you have planted your mums in a protected location. Mums do not like sites that are exposed to our brutal winter winds. In addition, heavy, wet soils in winter can be another hindrance to overwinter survival. Third, stop fertilizing the plants by the end of July. Fertilizing late in the season often encourages new growth that does not have enough time to acclimate in the fall. Fourth, be a little lazy in the garden in fall and leave the old foliage standing. Some research suggests that removing the old foliage in fall can reduce cold hardiness of mums. Lastly, mulch newly planted mums with wood chips, straw or other organic mulches to prevent the plants from lifting out of the soil during the freeze and thaw cycles during the winter.
While mums aren't the easiest perennials to grow and overwinter in the garden, they are often worth the effort. So don't give up on these autumnal beauties just yet, especially now that mum is the word…again.
ml: isugarden
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