Japanese Maples
by Joan Helbacka. WSU Master
Gardener, King County
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Mary Robson (Ret.)
Area Extension Agent
Regional Garden Column Sep 21, 2003
Fall in the Northwest means maple color and glory, especially from the garden
Japanese Maples. They’ve been cultivated since the 1600’s. Hundreds
of named cultivars have been bred, propagated and sold to eager gardeners.
They fit in even the smallest gardens, with some plants that grow only three
feet tall slowly. Even the largest upright varieties rarely grow to more
than 25’ in 50 years. Variations in leaf texture and form contribute
to their fascination.
Given a well drained soil mix they live happily in deck or patio containers
with otherwise minimal care. Soggy soil can be fatal. But they need water.
Don’t allow them to dry over summer: whether container grown or planted
in the landscape, consistent soil moisture is the key. Surprisingly, though,
long-established plants can tolerate quite a bit of summer drought (not to
be tried with newly installed ones.)
Japanese Maples are not greedy for nutrients: they like acid soils such as
we have, and most will grow well in our area with little or no fertilizer.
Over-fertilized plants may lack the very characteristics were chosen for. For
example, variegated cultivars may have the leaves “revert” to a
solid green, then return to the variegated form when less nitrogen is available.
Pruning also takes a light touch for these trees. If you’re removing
several branches, wait for winter when the tree is dormant. Minor corrective
pruning and training can be done almost any time. My particular pet peeve is
the lace-leaf varieties pruned into umbrella shapes. They look like dumpy dowagers
in hoop-skirts. The twiggy inner growth should be removed since it may invite
insect and disease problems by holding soggy leaves next to healthy bark. More
importantly much of the beauty of these plants is in the graceful curves of
the trunk and limbs. I like to see the branches pruned so that the natural
structure is enhanced and revealed. A well shaped lace leaf maple is as beautiful
in winter as it is clothed in leaves the rest of the year. Think Salome and
the Dance of the Seven Veils as you catch tantalizing glimpses of sinuous limbs
through the cascading leaves!
Some of my favorites are:
- A. japonicum ‘Aconitifolium’ or Fern Leaf maple. A splendid tree
with striking maroon and white flowers in the spring, deep green foliage in
the summer and spectacular fall color. It may reach a height of 15’.
- A. palmatum atropurpureum ‘Oshio beni’ a widely sold and popular
deep red leafed cultivar. It’s an upright growing tree with a spreading
canopy. It may eventually reach 20-25’ tall. The new growth is very
bright in spring, becomes a bronze during the summer and bright scarlet
in the fall.
- A. palmatum ‘Sango Kaku’ The common name is Coral Bark maple. It’s
outstanding feature is the brilliant color of the bark, particularly the younger
wood. It can get up to 20’ feet. The summer leaf color is a pleasant
green with a showy yellow gold fall color.
- A. palmatum ‘Shishagashira’ The common name is lion’s head
or lion’s mane. It has a closely spaced crinkled leaves on the twigs.
The fall color is a tawny gold that looks very much like a lions mane.
To keep the growth shrubby and compact, avoid over-fertilizing. Slow growing
and compact,
suitable for smaller gardens.
- A. griseum or Paper Bark maple. A hardy tree that originated in China rather
than Japan. The outer bark curls back to expose a smooth cinnamon color inner
bark which provides winter interest as well as contrasting beautifully with
the rich green summer foliage. It has brilliant red fall color that persists
until late in the season.
Visit the Washington Park Arboretum in Seattle this fall to see the largest
collection of Acer palmatum in any public garden in the country. Grounds and
trails are open daily from 7am to dusk. Drive gates are locked at dusk. Donald
G. Graham Visitors Center open seven days a week from 10:00 am - 4:00 pm. For
more information call 206-543-8800.
Hortsense: Managing plant problems with Integrated Pest Management
