Plant of the Week
Japanese Maple
Latin: Acer palmatum dissectum
It’s easy to become complacent with the glories of nature until
reminded of her by the subtle sledgehammer of fall color. This year, the display
on the mountainsides and streets of northwest Arkansas have been among the most
spectacular I recall.
But to really appreciate the autumnal transition to the fullest
extent it must be observed up close. A Japanese maple, Acer palmatum
dissectum ‘Seiryu’, growing near my patio allows me to follow this seasonal
transition from the comfort of my lawn chair.
Seiryu Japanese maple belongs to the "Dissectum" group of
cultivars but, instead of the more common wide-spreading, bush-like habit of
most selections in this group, Seiryu grows upright like any self respecting
tree. For a Japanese maple it’s fairly fast growing, putting on a foot or more
of growth a year but avoiding the twigginess of some selections. Its mature
height will probably be in the 15- to 20-foot range with a spread of 12 feet.
As a member of the Dissectum group, Seiryu has lacy green leaves
dissected into seven segments, each cut all the way to the petiole. In summer,
the tree has a light green color and reminds me of green lace curtains. In late
autumn, the leaves turn to an expectant green, then to a muddy orange and
finally a brilliant red, all within a 48-hour period.
This is the last tree to color in my landscape, usually turning
around Nov. 10 and lasting in full glory for about five days. Should a hard
freeze hit too early, no color will develop.
Predicting fall color displays in advance is import to the
Chamber of Commerce of any city expecting a boost in tourism during the fall
season, but it is hardly an exact science. Having read a number of these
predictions over the years, I can’t recall a single one that said, "This is
going to be a bum year - stay at home." Go figure! Like the quality of a vintage
wine, fall color depends on the weather. The best displays occur when we have
wet conditions during the early part of the growing season followed by late
summer drought.
The early season moisture helps ensure abundant growth with a
good load of leaves. The late season stress puts on the brakes to growth and
helps insure the leaves will be predisposed to turning when fall arrives. Too
much drought will cause leaf drop and burning, something the Chamber of Commerce
really hates.
The environmental trigger that initiates the change in leaf
color is the shortening length of the days, but the magnitude of color
development is intensified by temperature and sunlight conditions. Ideal
conditions are clear, bright days warming to room temperature during the day and
then dropping to almost freezing at night. Rain and wind during the display put
a quick end to the autumnal displays.
If Japanese maples produced no fall color display, I would still
want to use them in the landscape because of their elegance and beauty. I find
they do best when grown in an area with some shade, such as on the east side of
a building where protected from the hot afternoon sun.
Mine are planted under the high canopy of oak trees where they
do well, but their growth is no doubt slowed by competition for water. The
Dissectum group of cultivars, with their thinner leaves, is more likely to
suffer sunburn than selections with the normal leaf shape.
Of the several trees I have, not surprisingly, the fastest and
most lush growth occurs in fertile, moist soils. But the trees planted in my
rocky clay are prospering as long as they are watered during the summer.
By: Gerald Klingaman, retired
Extension Horticulturist
- Ornamentals
Extension News -
November 15, 2002
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