by Kevin O’Toole, Artist and Horticulturist
Chrysanthemums, originally from the Orient, are now prized the world over for their colorful blooms in fall. The mum has been woven into Asian culture for hundreds if not thousands of years and has long been the national flower of Japan. In the United States mums first became widely available in the early part of the twentieth century.
They provide glorious color for the garden throughout autumn and are available in a wide range of colors, with many variations within each hue. The name chrysanthemum is derived from the Greek language and means “gold flower”. While many varieties are still in the yellow-gold range, red, orange, white, purple, and pink flowers are also common. And if the colors weren’t enough to choose from, the flowers come in many different shapes and sizes. By planting a variety of mums with early-, mid- and late-season bloom times you can have an outstanding array of colors and textures from the end of August into November. In addition, mums are long-lasting cut flowers.
Commercially available mums can be divided into two distinct groups, namely “forced mums” and garden (hardy) mums. Forced mums are sold in full bloom no matter what time of year it is. They typically have single daisy-like blooms or cushion-shaped flowers. Forced mums come in exotic shapes such as spider, with delicate long arching petals, or quill with long hollow petals in a spiked shape, or spoon with blooms made up of many petals shaped like long spoons. Garden or hardy mums are available at nurseries in late summer and fall, and usually begin to bloom toward the end of August and finish up with the first heavy frost. They come in a wide range of colors but reds, oranges and yellows are most common. Hardy mums commonly have single daisy-like blooms, cushion style, pom-pom or small button style blooms, and are rarely available in the delicate long-petaled blooms more typical of the forced mums.
Mums are photoperiodic. This means they will only begin to set buds and come into flower naturally during 
the fall when the number of daylight hours decrease and periods of darkness increase. Forced mums can be bought in full bloom at anytime during the year because they are grown under controlled conditions and have been forced into bloom by the grower.
Several months before they are ready to be brought to market the grower will begin to increase the number of hours per day that the plants are in total darkness. Through experience and a little luck, the grower is able to bring the entire mum crop into bloom at the precise time he needs to sell them. The mum varieties that are most often used in the floral industry require 1 to 2 more months of long nights than the hardy mums that we typically plant in our gardens in the mid-Atlantic region.
If left to their own devices in an outdoor environment, forced mums would not even have a chance to set buds before they would be killed back by the first heavy frost. Garden mums require only 1 to 2 months of long dark nights to set buds and bloom, so are perfectly able to put on an incredible floral display before the first killing frosts of winter arrive.
Several years ago Behnke Nurseries began offering Belgium mums, amazing garden mums resulting from years of hybridizing and research done by Dirk Peters. These are note-worthy plants for several reasons, not least of which is the fact that they are literally covered with hundreds or even thousands of blossoms at a time. Most garden mums have rather brittle stems, and it is not uncommon to break a stem or two during transport. Belgian mums have been breed for durability and have remarkably flexible stems, making them particularly easy to transport from the nursery. Look for many new varieties and colors that we are offering this fall.
Small mums or cuttings can be planted in early to late spring but will require a great deal of “pinching” and care to achieve the dense mounded form and high bud count that is typical of the mums found in early fall at Behnke’s. The new growth tip of each stem has to be pinched or clipped back several times during the growing season or they will surely become tall and leggy with much fewer blooms.
Plant mums in late summer and throughout the fall when the selection is at its best. If you are interested in overwintering your mums you should plant earlier rather than later, at least six to eight weeks before the first killing frost in your area, so they have a chance to develop a strong root system. If your only goal is to have a spectacular fall floral display in your garden, grow your mums as annuals. Plant them when they are in full bloom, and remove them when they die back after the first heavy frost. Choose a sunny location with adequate drainage — mums will not tolerate “wet feet.”
Heavy clay soils will need to be amended with a generous amount of compost, well-rotted manure, or peat moss. Plant them carefully. Remove them from their pots and gently score (or rake) the rootballs to free the roots. Place them in the ground, taking care to plant them no deeper than they were in their pots. Mums have surface roots and will suffocate if planted too deeply. Water with a transplant fertilizer, such as Bonide Plant Starter Solution ®, to stimulate root growth.
Most gardeners today suffer from a lack of space and dispose of garden mums once they have passed their peak bloom. However, if you have plenty of space, you might try to overwinter your mums. You can move them in the spring if they are taking up a prime color location. Garden mums will be content to pass the summer in a large vegetable garden or any sunny spot out of the way.
After they bloom, remove the faded blooms, but don’t cut the stems back. Don’t try to move them at that point, even if you don’t want them to stay where they are through the next growing season. Repeated freezing and thawing of the soil can heave plants out of the ground, exposing their roots to the elements. Newly-transplanted mums are especially vulnerable to heaving. Having well-established plants, or a layer of straw, pine boughs, or other springy material applied over the plants in late fall will help to minimize this problem. Lightweight mulching material will allow good air circulation, which is important. 
When growth resumes in the spring, carefully clear away the mulch and remove any dead foliage. Now is the time to move them to a summer home, if necessary. Replant the clumps in good quality soil, which drains well -this is essential for healthy mums. We recommend a dose of transplant fertilizer to stimulate root growth.
Mums, being surface feeders, appreciate fertilizer applied as a top dressing. About the end of May, scratch a granular fertilizer for flowering plants (such as FlowerTone ®) into the soil around each plant. Apply granular plant food every four or five weeks till August or supplement with water-soluble fertilizer throughout the late spring and early summer to encourage branching and bud formation.
How to Plant