Chrysanthemum Culture

University of Rhode Island GreenShare Factsheets

Chrysanthemum Culture

The garden chrysanthemum is one of the most exciting flowers that can be grown in the home landscape for late summer and fall display. Garden mums require a minimum amount of care and do well even under some adverse conditions. There are cultivars (varieties) with color that range from white to yellow, pink, bronze, red and their hues. With hundreds of cultivars available, the choice of plants to grow is unlimited. To have a more interesting collection of mums, however, plant cultivars of various types such as singles, anemones, decoratives, pompons, spoons, spiders and standards.

The term garden mum applies to chrysanthemum cultivars that will flower naturally and be early enough to avoid a heavy frost. The term "hardy" has been abandoned by most suppliers, as hardiness of garden mum cultivars may vary significantly from one season or area depending on weather and cultural conditions.

Garden chrysanthemums are planted in the spring from established cuttings. They used to be offered primarily in the fall as clumps, but today the plants are being sold along with annual flowers and vegetables. Most of the plants are sold in pots that must be removed before planting. The plants generally have had at least one pinch, which results in a well-branched plant. The site for planting should be well drained and receive plenty of sunlight. The plants should be spaced 18 to 24 inches apart; some of the more vigorous cultivars may need 30 to 36 inches. Enough space should be allowed so the plants can develop to their maximum potential. Plant to the same depth they were growing in their containers and no deeper. The plants should be thoroughly watered after planting.

Fertilizing the plants will develop lush, green foliage with optimum flowering. Apply a complete dry fertilizer such as 5-10-5, 5-10-10, 5-20-20 or equivalent at the rate of two to three pounds per 100 square feet of bed area. The dry fertilizer should be watered in after it is applied. Soluble fertilizers such as 15-30-15, 20-20-20 are also quite satisfactory. Follow the rate of application on the package or container. Fertilization can be discontinued after flower buds form in late July.

As the plants grow, they should be pinched to produce compact plants with more flowers and to avoid tall, leggy plants. If the plants become too tall, light will be excluded from the lower part of the plants, resulting in unsightly dead leaves. New shoots should have the tops removed by pinching them off between the thumb and forefinger. This practice should be followed, leaving 2 or 3 leaves on the shoot, whenever the shoot reaches 3 or 4 inches in length. This practice can be timed so that the fertilizing and pinching can be done the same day. This will usually be once a month from May-July. However, with most garden cultivars, the last pinch should be made no later than August 1. If pinching is continued after this date, flower buds will be eliminated from the plants. Follow the directions for each specific cultivar.

Weeds, as with many other plants, may present a problem with growing garden chrysanthemums. These can be removed by hand, or an organic mulch could be used at the time of planting. Materials such as shredded bark, wood chips, coarse peat moss, peanut hulls, sawdust or straw will effectively reduce weeds and conserve moisture in the soil. Organic matter that breaks down rapidly, such as straw, will require an extra application of fertilizer to compensate for the nitrogen loss. Apply this fertilizer in addition to that which is applied for the plants. Landscape fabrics and decorative gravel are also effective in weed control.

Application of adequate amounts of water is a critical cultural practice. During some summers, rainfall may be plentiful enough to eliminate most additional watering. However, the plants should be watered whenever the soil starts to dry. Apply enough water to soak the soil to a depth of four to six inches. This is best done by using sprinklers rather than hand watering. It is best to apply the water during the day so the foliage will dry off before nightfall to avoid leaf and flower diseases.

The most common insect pests of chrysanthemums are aphids and two spotted spider mites. See GreenShare Factsheets on these insects for cultural control recommendations. Powdery mildew and verticillium wilt are two important chrysanthemum diseases--verticillium wilt is difficult to control, and chyrsanthemums should not be planted in contaminated areas for several years.

The garden chrysanthemum, in most instances, should be considered an annual flower by homeowners. When frost kills the tops of the plants, cut off the dead stems and remove from the garden. Sometimes, mums will come up the next spring if just the tops of the plants are cut off. If you prefer to try to keep the plants through the winter, cut off the dead tops and cover the plants with mulch to a depth of three to four inches.

For gardeners looking for specific cultivars, the following are widely available in the trade and should do well in the Northeast:

White: Encore, Illusion, Nicole, Tolima
Yellow: Donna, Goldmine, Jessica, Target
Pink: Debonair, Naomi, Stardom, Sundoro
Bronze: Ginger, Grace, Sandy, Triumph
Red: Bravo, Minngopher, Remarkable

Adapted from Charles T. Behnke, Ohio State University Extension , 2000

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For more information, call the URI CE Gardening and Food Safety Hotline at 1-800-448-1011 or (401)874-2929 from outside Rhode Island; Monday-Thursday between 9 am and 2 pm.

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