Asian Maples for Cold Climates
by Jon Carlson

ARTICLE FIRST APPEARED: 1998 Summer

While the graceful shape and delicate leaf patterns of Asian Maples appeal to gardeners everywhere, those of us who garden in chilly northern Illinois and southern Wisconsin have often shied away from using Asian Maples--maples which are native to Japan, China, and Korea--in the landscape for fear that they are not hardy. While it is true that our cold winters present a few problems for growing some Asian Maple varieties successfully, my years of experimentation have shown that we are more nervous than we ought to be. Combining knowledge of the trees' needs with proper soil and siting and choosing the most hardy varieties will allow you to easily add these gorgeous specimens to your landscape.

Our nursery, J. Carlson Growers, Inc., is located on the east side of Rockford, the second largest city in Illinois. I assume that we're second in population only because Rockford's climate is colder: this region is Zone 4b, compared to Chicago's Zone 5 and the North Shore's Zone 5b. In addition to cold, the trees in our nursery are also subjected to winds much stronger than you would typically receive in a more urbanized areas where buildings provide some measure of protection. In other words, if we can do it, you can too.

Location is the most important factor in planting Asian maples. No matter which variety you select, you must plant them in the understory of larger shade trees, preferably out of the way of the extremely drying winds of winter. [In winter when the ground is frozen, there is no way for trees to compensate for the loss of water caused by wind action. The stress of this deprivation is often fatal to Asian Maples.] The ideal site for Asian Maples is under a larger tree located on the east side of a wind-blocking structure (a house, garage, or thickly-planted windbreak) so long as the tree receives about 1/2 day of sun. In fact, by planting under larger trees, you will be assuring yourself of beautiful fall colors since the trees will be protected from hard frosts.

Like many other plants, Asian maples like loose, well-drained soil with ample organic matter. They should be planted in the spring, so that the new transplants have time to re-establish their root systems prior to winter. Gardeners should not expect much top growth in the first season after planting Asian Maples as they are putting their energies into root formation instead. A good mulch is essential, of course.

The Asian Maples range in size from 20 feet down to Bonsai size. In this article, I have listed small trees, but if you are looking for shrubs, the most hardy and most common Asian varieties are Acer palmatum 'Shaina' and 'Murasaki Kiyohime'.

We advise gardeners to start out with the hardiest Asian Maple varieties and then venture to more challenging varieties as you gain experience and success. The following varieties all grow well in our climate if planted in good soil and in an understory situation:

Fullmoon Maple [Acer japonicum]: I find the Fullmoon Maple hardier of cold than the Japanese Maple, Acer palmatum, but just as handsome. It grows 30' by 30'.

Cutleaf Fullmoon Maple [Acer japonicum'Aconitifolium']: The leaves of this 20' x 20' tree are deeply cut and fernlike. They turn ruby red in the fall.

'Green Cascade' Japanese Maple [Acer japonicum 'Green Cascade']: This beautiful tree cascades with deeply-lobed green leaves which turn yellow/orange in the fall. 'Green Cascade' is wider than it is tall: its mature size is 6' x 10'.

Manchurian Maple [Acer mandshiricum]: Slow-growing, this excellent trifoliate maple has great orange/red fall color. Grows 18' by 10' feet.

Korean Maple [Acer pseudosieboldianum]: This Korean tree has attractive, glossy-green, many-lobed leaves and brilliant orange/red fall color. It will mature to 25' tall by 25' wide.

Golden Fullmoon Maple [Acer shirasawanum 'Aureum']: The leaves of this 25' x 25' Japanese native are a pale golden yellow throughout the season. It is vase-shaped and the branches look like the strata of clouds. Very nice!

Threeflower Maple [Acer triflorum]: This rare trifoliate maple is a cousin of Paperbark Maple [A. griseum], and is dependably red/orange in the fall. It grows to 30' x 30', and has shaggy, dark brown bark. Best in sun.

If you can definitely provide wind protection from the northwest, I recommend the following varieties of Asian Maples:

Paperbark Maple [Acer griseum]: One of the greatest small trees. It grows higher (45') than it does wide (15'), generally an oval shape. Exfoliating bark and red fall color! An aristocrat!

Bloodgood Japanese Maple [Acer palmatum 'Bloodgood']: The leaves of this upright 20' x 20' tree are the standard for red among all Japanese Maples. A classic.

Trompenburg Maple [Acer palmatum'Trompenburg']: The leaves of this 20' x 10' tree are unique: each purple-red lobe rolls up to form a tube. The tree turns dark red in the fall.

The last group of maples are the most challenging. These small "laceleaf" maples require the most protected of sites: definitely the east side of a building or windbreak. In addition, I would recommend a shelter of burlap in the winter during the first few years following transplant. The laceleaf group includes:

Ever Red Laceleaf Maple [Acer palmatum dissectum 'Ever Red'] which grows about 4' high and 5' wide.

Tamukeyama Laceleaf Maple [Acer palmatum dissectum 'Tamukeyama']: Very slow-growing (10' in 50 years!), this tiny, cascading tree's foliage opens deep crimson but changes to scarlet by autumn.

Lion's Head Maple [Acer palmatum 'Shishigashira'] which grows 6' tall by 4' wide.

This article does not provide space for describing the incredible number of Asian maples actually available. Just a few more rated to Zones 4-6 include: Trident Maple [A. buergeranum]; Amur Maple [A. ginnala]; Miyabe Maple [A. miyabei]; and some 40 varieties of A. palmatum. Stay tuned, for research horticulturalist Abbas Shirazi, Ph.D, and tree breeder Susan Wiegrefe, Ph.D, both of The Morton Arboretum, are evaluating Asian maples for their hardiness in northern Illinois.

The many shapes, textures, and colors of the Asian Maples have endeared these trees to me. They are a welcome addition to a garden. With careful siting and judicious selections, you will have them gracing your landscape and offering enjoyment for years to come.#

Jon Carlson is owner of J. Carlson Growers, Inc., a retail nursery and landscape supplier located in Rockford, IL. [See advertisement in TWG Resource Guide.] He has been selling Asian Maples, including all of the selections described in this article, for 16 years. You may reach him at (815) 332-5610 or fax him at (815) 332-7495.

Where to Learn More About Asian Maples

If you wish to see color illustrations of these trees, Jon Carlson recommends the book entitled, Japanese Maples (2nd edition) by J.D. Vertrees [Timber Press, 1987, 189 pp, 250 color photos, $40]. For seeing more of these trees "in person", the biggest collection in the Upper Midwest is located at The Morton Arboretum. Anderson Gardens, a Japanese garden located in Rockford, is an excellent place to see these trees, as is Longnecker Gardens, a wonderful arboretum located in Madison, WI and operated by the University of Wisconsin, also boasts an extensive collection of Asian maples.

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