University of Vermont Extension
Department of Plant and Soil Science

Garden Chrysanthemums                  OH 43

Leonard Perry, Extension Professor

The garden chrysanthemum is one of the most exciting and colorful flowers that can be grown in the home landscape.
It requires a minimum amount of care and does well even under somewhat adverse conditions. There are cultivars
(cultivated varieties) with color that can stretch the imagination of most gardeners. 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.

In our area, garden chrysanthemums are planted most frequently in the fall. Most of the plants are sold in pots, which
may either be left on, if they are the kind that break down, or else removed before planting. The plants generally have
had a 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, and 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. Plant to the same depth they were growing in their pots or containers and no
deeper. The plants should be watered in thoroughly after planting.

The garden chrysanthemum in most instances should be considered an annual flower. Therefore, when frost kills the
tops of the plants, these dead stems are cut off and removed from the garden. Nothing else is done and if the plants
live over the winter and come up next spring, fine. If they don't, then buy some new ones next fall. UVM research in
South Burlington on dozens of currently offered varieties has shown many to live at least one winter, but none to
overwinter consistently year to year. However, many growers prefer to try to keep them over and, therefore, cut off
the dead tops and cover the plants with mulch to a depth of three to four inches. The plants can be dug after frost and
healed in a cold frame, if one is available.

For those overwintered successfully, fertilizing the plants will develop good green foliage with optimum flowering.
Apply a complete fertilizer such as 4-16-16, 5-10-5, 5-10-10, or 5-20-20 at the rate of 3 to 4 pounds per square
feet of bed area. An application of fertilizer should be made monthly during the growing season. he fertilizer should be
watered in after it is applied. Soluble fertilizers are also quite satisfactory to use if desired. Follow the rate of
application on the package or container. As the plants grow, they should be pinched so as to produce more compact
plants with more flowers. If this isn't done, the plants will become too tall and leggy. Also, if the plants become quite
tall, light will be excluded from the lower part of the plants resulting in unsightly dead leaves.

New shoots should have the tips removed by pinching them off between the thumb and forefinger. This practice should
be followed, leaving two or three leaves on the shoot, whenever it becomes 3 to 4 inches long. This practice can be
timed so that the fertilizing and pinching can be done the same day and it will usually work out to be once a month;
however, with most garden cultivars, the last pinch should be made no later than July 1. If pinching is continued after
this date, flower buds will be eliminated from the plants.

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, or straw will do a good job of keeping the weeds down and conserving moisture in the soil if
applied about 2 inches deep. For those organic materials that break down rather rapidly such as sawdust, an extra
application of fertilizer will be needed on the plants. Apply this fertilizer in addition to that which is applied for the
plants. However, you will only need it a couple of times and then stop.

Other methods of weed control are the use of chemicals and inorganic mulches. Such pre-emergence chemicals can be
very effective if applied early before weeds appear. Plastic films are also quite effective as are hard mulches such as
decorative gravel, stones, marble chips, and similar materials.

One of the very important cultural practices with garden chrysanthemums is adequate amounts of water. During some
summers rainfall may be plentiful enough to eliminate most additional watering. However, when the soil starts to get dry
the plants should be watered. Applying enough water at a time to soak the soil to a depth of 4 to 6 inches is necessary.
This is best done by using soaker hoses, or hand watering if just a few plants. It is better to apply the water during the
day so the foliage will dry off before nightfall. Otherwise, leaf and flower diseases can become a problem.

Fortunately for garden chrysanthemum growers, most insect and disease problems are controllable. The common
insect pests are aphids and red or two-spotted mites, which can usually be controlled by spraying with an insecticidal
soap or insecticide. Mildew can become a problem in late summer and fall and can be controlled with sulfur. Most
other fungus diseases can be kept in check by using fungicides. One disease that cannot be controlled is verticillium
wilt. Discard infected plants and plant resistant cultivars.

(Adapted from James L. Caldwell, The Ohio State University)

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Last reviewed 2003