Published: April 28, 2008 03:19 pm         

PLATEAU GARDENING: Nursery-recommended Japanese maples

Last year I interviewed experienced nursery retailers with businesses in Crossville, Cookeville and Sparta. They recommended good Japanese maple varieties for home landscapes in our area. Readers shopping for new trees and shrubs or replacing ones that were badly damaged by the April 2007 freeze have asked to see again that list of nursery-recommended Japanese maples.

A common mistake of those outside the nursery industry is expecting everything at a local garden center labeled “Japanese maple” will look alike. They aren’t all short, shrubby trees with a broad, weeping form and reddish-purple, lacey leaves. While most Japanese maples are the size of large shrubs or small trees, heights vary from 6 feet to 30 feet. These plants exhibit different growth habits, leaf shapes and foliage colors. There are upright, vase-shaped Japanese maples as well as others with a broad, mounded look, wider than they are tall. If fall color is an important characteristic, be sure to ask about the color of autumn foliage before making your final selection this spring. Japanese maples have good fall color but the leaves may be yellow, gold or scarlet in autumn depending upon the specific cultivar. Not all turn red in the fall.

Japanese maples are in the botanical group Acer palmatum. The “palmatum” part of the botanical name describes a leaf shape that has points (called lobes) which fan out from the center like fingers extending from the palm of your hand. Leaf appearance is one defining characteristic of Japanese maple cultivars. Some have leaves with five to seven broader lobes. Others, classified as “dissectum” varieties, have deeply cut lobes which give their leaves a delicate, lacey look.

The following varieties have an upright growth habit and broader (not dissectum type) leaves:

Acer palmatum ‘Oshio Beni’ has an upright form with a spreading canopy which may grow to between 20 and 30 feet high. Its leaves are broad and serrated along the edges. Oshio Beni’s new spring leaves are bright red-orange when they first appear. By summer, the leaves turn a bronze, reddish-green. Autumn foliage is scarlet red

The coral bark Japanese maple grows to 20 feet or more. Its foliage color changes throughout the season. When they open in the spring, coral bark leaves are a yellow-green color with reddish markings. Then leaves mature to a bright green in summer. The foliage turns a rich gold touched with lighter-yellow and apricot highlights in autumn. The common name coral bark refers to the shiny, red bark covering younger branches. This maple is known by either of two botanical names — Acer palmatum ‘Senkaki’ or Acer palmatum ‘Sango Kaku.’ The Japanese words Sango Kaku, which translate to “coral pillars” in English, also reference the specimen’s distinctive coral colored branches. Those red twigs are said to seem to glow on sunny winter days. This specimen does well when located in a spot which receives morning sun, part shade in the afternoon and is sheltered from the wind.

Bloodgood (Acer palmatum var. atropurpureum ‘Bloodgood’) matures at 15 to 20 feet in height. Bloodgood is an older cultivated variety with reddish-purple leaves which turn bright red in the fall. Breeders of red Japanese maples select plants for deep, purple-red leaves that keep their color in high heat without getting leaf-scorch or turning green in direct sun. Emperor I is a newer cultivar similar in appearance to bloodgood but a bit taller (25 to 30 feet) with a broad rounded crown. Emperor I is judged to be superior because of better heat tolerance.

Plateau Gardening is written by Tennessee Master Gardeners about home landscapes and gardening in our state’s Upper Cumberland Region. For answers to specific yard and garden questions or to learn how to become a Master Gardener, contact UT Extension Cumberland County, P.O. Box 483, Crossville, TN 38557, (phone 484-6743). E-mail inquiries to mgardenerrae@frontiernet.net. E-mail questions may be answered either individually or through future newspaper articles.