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Plant of the Week
Weeping Chrysanthemum
Latin: Dendranthema grandiflora
Weeping plant forms have always intrigued me, partly
because of their graceful curves and partly because of an interest in the
odd and unusual.
In my college days, I ran across an advertisement for a weeping
chrysanthemum, a plant I only knew as a righteously upright grower. So,
forgetting the advice my mother taught me about things being too good to be
true, I dutifully sent in my $5 to check it out.
By return mail, I received a chrysanthemum cutting, a coat hanger and a
crudely drawn illustration explaining how to train the plant to make it grow
against the forces of nature. Gardeners should hold onto their money. I’ll
share the secret for free.
Weeping chrysanthemums are often used as a part of flower show displays and
in public display gardens. The effect can be spectacular with individual
plants having hundreds of flowers. To achieve the truly spectacular size
attained in some of the display gardens plants must be grown about nine
months to achieve the desired effect. By comparison, the chrysanthemums we
see in the stores each fall are about three-months old.
Chrysanthemums are classic short-day plants with blooming controlled by the
relative length of the day and night. When the night gets longer than nine
hours, chrysanthemums begin to set flower buds. In Arkansas, this usually
occurs about mid August with blooms appearing about eight weeks later.
The bushel basket size garden mums we see in the stores were simply started
earlier in the summer and allowed to grow longer before short-day conditions
arrived and triggered flowering. The little plants in 6-inch pots were
planted about July 1 and only allowed to grow a few weeks before the arrival
of short days stopped their vegetative growth and triggered the formation of
buds.
Weeping chrysanthemums are started in January and grown in a greenhouse
under long-day conditions. To keep the plants from setting flower buds,
lights are set to come on every night above the plants from 10 p.m. until 2
a.m. This breaks up the night into two segments, each shorter than the nine
hours required to trigger flowering. The plants are grown in nursery pots
with a tall, unpinched stem affixed to a bamboo pole. By the time spring
arrives - and the night lighting no longer needed - the plants will be 3 to
4 feet tall and straight as a telephone pole.
At this point, the plants can be moved outside. A Florida grower, who
specializes in weeping chrysanthemums, has a series of chain-link fences
built at 30-degree angles with a shelf at the top to hold the pot. Once the
tall, spindly plants are moved outside and the stake removed, the plants
topple over. The length of the stem at the time the stake is removed
determines how long the weeping plant will be. Now, with the plant stem
upside down, there is no hormonal control from the terminal bud and all of
the side buds begin growing, just as a tree will send up side shoots if it
falls in the forest.
These side shoots - all of which now grow up, not down - are then pinched
and pruned as needed to achieve the desired shape and form for the plant.
All pruning and pinching is discontinued after late July because the plants
will soon be setting flower buds as short days of autumn arrive. While these
cascading beauties have little place in the average suburban garden, it’s
always fun to be let in on the secret of how these horticultural novelties
are produced.
By: Gerald Klingaman, retired
Extension Horticulturist
- Ornamentals
Extension News -
November 3, 2000
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