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Propagation
Propagation of Japanese maples is almost always by grafting. A few cultivars
can successfully be grown from cuttings, but ususally cutting-grown trees
do not have vigorous roots and the trees fail to thrive. Grafting puts
the desired leaf and habit on a rootstock that has demonstrated vigor.
Of course, the trees produce seeds, but seedlings don't reliably produce
plants that look like the parent. For that reason, a seedling of a named
cultivar cannot be given that cultivar's name. A 'Bloodgood' seedling
isn't a 'Bloodgood'. In fact, it may very well be green, instead of red.
Seeds are the source of new culitvars, though, and many seedlings are
handsome trees, even if they don't merit introduction as new cultivars.
Grafting is done onto seedlings from Acer palmatum species trees
that have shown good vigor. This may be done in later winter/early spring,
on wood that has been cut when the trees were dormant, and held refrigerated.
These days, many grafters are doing late summer grafting instead, taking
advantage of the trees' midsummer growth spurt.
We can't teach you how to graft via email; break down and get a book.
We use a side veneer graft in late August-September, and staple a plastic
bag around the graft for a few weeks. The photo on the right shows the
cut made on the rootstock, which is matched by an angle cut on the scion.
The side veeneer graft is illustrated at the following link. The text
applies to late winter/spring grafting, so ignore it if you're doing late
summer grafting, which we recommend. Look at the description of the splice
graft as well, to better see the angle of the cut.
http://www.ces.ncsu.edu/depts/hort/hil/grafting.html
Here's an article on grafting Japanese maples:
http://www.ag.auburn.edu/landscape/STGOnovember98.html#grafting
And here's a photographic walkthrough:
http://webpages.charter.net/wbshell/garden/graft1.htm
Hardiness and Care
Many Japanese maples are hardy in zones 5-9, but at the low end of their
range, they won't grow as large, and require mulching of the root zone
before the ground freezes, as well as protection from drying winds. Dieback
of branches may also occur. Some cultivars may not be hardy at all in
zone 5. Since some cultivars are quite new, and since rare cultivars may
not have penetrated much into colder regions, there is sometimes not enough
data to determine whether a given cultivar will take zone 5 winters or
not. Among those known to be hardy in zone 5, Bloodgood, Burgundy Lace,
Garnet, EverRed, Inaba Shindare (Red Select), Viridis, Sherwood Flame,
and Moonfire are some of the most commonly found selections. Species other
than A. palmatum that are mostly hardy include A. buergerianum, A. davidii,
A. ginalla, A. japjonicum, and A. shirasawanum.
At the other end of the spectrum, folks trying to grow these trees in
the hot, humid south should be aware that most will need protection from
afternoon sun, and should be mulched to help keep the soil cool. Just
as some cultivars fare better than others in cold, some are better adapted
to warm, humid environments. Cultivars recommended for the southeast as
far south as north Florida include Arakawa, Beni maiko, Bloodgood, Fireglow,
Garnet, Inaba Shidare (Red Select), Kamagata, Kashima, Kiyo Hime, Red
Dragon, Sango Kaku, Seiryu, Shindeshojo, and Tamukeyama. Other cultivars
may do well, but again there is little data to go on in many cases. Residents
of zone 10 have seen these trees and want to grow them, but they should
be advised that Acer palmatum does not thrive in climates that don't have
temperatures below 45F for several weeks. This is because the trees need
a cold dormant rest period each year, and if they don't get it, will fare
poorly. Sure, you can see these maples looking great at Disneyland and
Disney World, but what you don't know is that they are replaced about
every three years, because they start to decline as soon as they miss
a dormant period. If you can afford to replace them that often, knock
yourself out, but expect leaf burn and poor fall color in hot, dry, hard-water
areas such as southern California. In the humid south, watch out for fungal
diseases.
Many Japanese maples will take full sun in mild-summer areas, and fall
color is usually enhanced by a sunny exposure. However, some of the more
delicate-leafed cultivars require shade from scorching sun. The coarser
red laceleafs will take full sun in zone 8, but they may sunburn for a
year or two before they establish their root systems. In the south or
other intense summer climates, afternoon shade or dappled shade is better.
Virtually all cultivars will be happy in light shade in any climate.
Although considered relatively slow-growing, Japanese maples may reach
2/3 of their height fairly quickly. After that, they slow down, fill in,
and creep toward their mature height. For this reason, heights are often
reported at a certain number of years, usually 10 or 15. Dwarf uprights
are usually 12' or less at maturity, laceleafs may also reach this height,
but may take 50 years to do so. A few very dwarf cultivars top out at
3-4'. Height can be controlled by thoughtful pruning, beginning when the
tree is young, or may be restricted by growing it in a container. Because
they do not have terribly vigorous roots, Japanese maples are naturals
for container culture and bonsai.
The most important cultural practice is to keep the soil at an even moisture
level. Slightly moist is best, but slightly dry will be tolerated as long
as it is consistent. Although virtually all Japanese maples do very well
in containers, even soil moisture is somewhat harder to maintain in pots,
so care should be taken. Container-grown trees will be smaller than ground-grown
ones, but maples do not have aggressive roots, and are quite content to
stay in pots indefinitely, so long as constant soil moisture is maintained,
and the pots are insulated against very cold and very hot temperatures.
Avoid balck pots in summer sun. The shallow root zone is the most vulnerable
part of the tree. It likes moderation.
Don't worry about adding all kinds of stuff to the soil. Maples are adaptable,
and require only good drainage and tilth. Add gypsum if you have very
hard water. A balanced fertilizer applied once in early spring and again
in July is sufficient in most circumstances. Moderate application of a
slow-release fertilizer such as Osmocote is easy and adequate. If your
soil is generally fertile, and gets the occasional addition of compost
or leaf mulch, additional fertilization may not be necessary at all.
Pruning
Except for removing diseased or rubbing branches, pruning is not required
if you have enough space and don't mind tall trees. Japanese-style pruning
calls for the removal of the fine, twiggy growth in the tree's interior,
in order to display the branching structure. Apart from that, how to prune
depends on who's talking. Some say cut close to bud pairs, don't leave
stubs, and don't paint the cut with anything. Others say Japanese maples
are exceptions to these rules. Most, but not all, sources agree that late
fall is the time to do it, but Vertrees, who "wrote the book"
on Japanese maples, says major pruning should be done just before leaf
production in spring, and corrective pruning done any time of year. For
some articles on pruning strategies and techniques, have a look at the
following links:
http://www.sabot.org/gguide/japan.htm
http://www.mountainmaples.com/WS4D_Cookie=11.18.02_16,13,10_1/article2.html
The Japanese Garden Journal is a subscription magazine available at this
website: http://www.rothteien.com/index.html
http://commserv.ucdavis.edu/cetulare/mg/articles/n052401.htm
A book that might be useful:
The Pruning of Trees, Shrubs and Conifers George E. Brown Timber
Press, 133 SW 2nd Ave., Ste. 450 Portland, Oregon 97204 USA Toll-free
telephone: 1-800-327-5680 Telephone: 1-503-227-2878 Fax: 1-503-227-3070
Email: info@timberpress.com
http://www.timberpress.com
Books on Japanese Maples
Since the late 80s, the uncontested best reference on this subject has
been Japanese Maples by J. D. Vertrees. The main difficulty with
this book has been its lack of revision since Vertrees' death and the
consequent lack of information on newer cultivars. In the past couple
of years, two things have happened to improve this situation. First came
the publication of Maples for Gardens, by C.J. van Gelderen and
D.M. van Gelderen. The van Gelderns are from the family that owns Firma
C. Esveld in The Netherlands, a nursery that has perhaps the largest collection
of Japanese maples in the world, and which has introduced several varieties.
Their book includes many of the newer cultivars, and also includes a more
exhaustive treatment of other maple species than the origional Vertrees.
Second, there has now been a revision of the Vertrees book., Japanese
Maples: Momiji and Kaede Third Edition by J. D. Vertrees and Peter
Gregory, Revised and expanded by Peter Gregory. Gregory is chairman of
the International Maple society. He has included new cultivars, rearranged
the descriptions for easier reference, added photographs, and updated
terminology.
Another book of possible interest is The Gardener's Guide to Growing
Maples by James G. S. Harris. Harris is an English nurseryman whose
work treats all 125 species of Acer.
All three books are available from Timber Press. http://www.TimberPress.com
Back to Maple Home
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.....Introduction
to Japanese Maples, continued.
