by Glenn Davis, UCCE Master Gardener, El Dorado County
November 2002
At this time of the year most of the garden color consists of
late blooming roses, bless their soul, and leaves turning color. One exception
is our old standby the Chrysanthemum, or “Mums’” for most gardeners. There are
about 160 species worldwide and include, along with our Florist Chrysanthemums,
Shasta Daisy, Marguerite, and Painted Daisy to mention a few. Nurseries know
that customers like to see the flower color when they are purchasing and now is
the time they display their mums.
The flower shape has more than a dozen classes and the care
and form of the plant is dictated by the class. Unfortunately that care falls
on the gardener’s shoulders. If you plant mums so they are protected from
extremely hot afternoon sun, in well-drained soil, water consistently,
fertilize occasionally and leave them alone they will do just fine. They will
have flowers but they won’t resemble those mounds of color we see in the
nursery or florist shop.
Chrysanthemum cultivars come in different sizes, tall, medium
and short and the flower size generally corresponds to the plant size. If left
alone most chrysanthemums will produce flowers of the same size, with a good
gardener’s care, the flower and plant can become a showpiece. It is not unusual
to see prize winning chrysanthemums with flowers from four to six inches in
diameter and to see cascades three to four feet in length completely covered
with small blooms. For gardeners to produce showpieces like this they must
start when the plant is first starting to emerge in the spring.
If you purchase a chrysanthemum now, purchase it for color,
form and size. Record the name and whether it is a tall, medium or short plant
and if the flower is small, medium or large. Plant it now and take care of it
until it dies back and leave the dead stalks on it. If you are in a hard freeze
area, dig it up and replant it in a more moderate area, if you are in a warmer
area, mulch over it.
In the spring when the new greenery starts to emerge at the
base of the plant, you can dig and divide the clump and that is when you cut
back the dried stalks. When the plant starts to grow, refer to your records;
generally speaking you want about three main stems on tall, large flowering
chrysanthemums, and you must remove the weaker lateral stems to allow the
growth to concentrate on these main stalks. To prevent the plant from becoming
too leggy cut it back to about 15 inches in early July. Medium sized
chrysanthemums can be treated in the same manner or they can be limited in
size. Small flowering chrysanthemums are usually grown in a single mound or
spray manner.
In addition to the pruning of the laterals there are two more
terms you should be familiar with when growing chrysanthemums, disbudding and
pinching. Disbudding means removing the flower buds from the plant and pinching
means removing the terminal ends of the branches. For chrysanthemums the
pinching means taking off the tip back to the next couple of leaves. When a
rooted stem starts to grow in the spring the usual procedure is to cut it at
four inches when it is about a foot tall. It will branch at the cut and if you
want, you can cut these branching laterals again to force the plant to fill in.
Eventually the laterals will reach a terminal with buds on the end and there
will be buds at the first and second cuts. In addition to the terminal buds,
there are second and third buds where the plant has been cut, these are called
second and third crown buds. At the base you may also have a bud that is known
as the break bud. It will appear that each cut will result in a leaf and flower
bud.
The terminal buds usually are all flower buds and have the
best color; lateral crown buds consist of flower and greenery buds and lack the
intensity of color found in the terminals but do grow faster. For top flower
quality at the terminal, disbud the lateral crowns and when the terminal bud
starts to mature remove all of the buds around it leaving you with one or two
flowers on a stem. For large crown buds you must remove the greenery buds that
surround it. All of the cutting, pinching and disbudding should be completed by
mid-summer. For mounding and cascading chrysanthemums, continuously pinch back
the tips as they grow, this will force the production of more greenery and
flowers.
During the growth period fertilize regularly with a balanced
fertilizer up to flower production; after flower production fertilize with
0-10-10. About the only insect problems are aphids and mites that can be hosed
off with water or killed with an application of light horticultural oil. Don’t
be afraid to experiment a little, chrysanthemums are good hardy plants.