Japanese Maples
by Pam Wallace, UC Master Gardener

Japanese maple trees are a welcome addition to any landscape. Want to frame an entryway, create a colorful focal point in your yard, or shade a window without blocking the view? Then look no further than the Japanese maple. Their diversity of size, color, shape, and form is so great, that their graceful beauty will fill any need.

One look at the leaf of a Japanese maple, and you can see how it got its botanical name, Acer palmatum, which means "resembling a hand". There are hundreds of species of Japanese maples, but most nurseries feature only a few of the upright and weeping forms. Upright trees typically have multiple trunks or branches very close to the ground, and reach heights of 15-30 feet at maturity. The weepers, or thread-leaf varieties, are very slow growing and more closely resemble shrubs than trees. Leaf color for both forms range from yellow-green to maroon-red to a variegated white and pink.

The landscaping possibilities for Japanese maples are endless. They are effective as small specimen trees in containers, accent plants in flower beds, patio trees in dappled shade, and in large areas, planted in groves like a woodland setting. Their natural growth habit is a broad, rounded shape with a layered branching structure similar to that of the flowering dogwood.

Plant them where you can enjoy their interesting features all year round. In spring, the red-leafed varieties appear incandescent when the morning sun shines through them. Leaves will turn from red to green during summer, then as temperatures cool in the fall they will display a tremendous blaze of color. During winter, the interesting limb scaffolds and bark color will provide enjoyment. 'Senkaki' or 'Sango-kaku' has unusually beautiful coral colored bark that is incredulous during the gray winter, especially when floodlit during the evening.

Acid-loving plants such as azaleas, begonias, rhododendrons, gardenias, plus perennials and bulbs make excellent companion plants. I have two maples planted in a flowerbed outside my living room. Three large picture windows frame a red-leafed and green-leafed maple tree each under-planted with azaleas. My favorite morning view is to glimpse the dappled sunlight shining through the maple leaves onto the azaleas.

Although delicate in shape and form, the Japanese maple is actually a very hardy tree needing little care. It does require moist, well-drained soil, so prepare your site accordingly. These trees do not have invasive or deep roots, so be sure to water well and frequently, especially during the summer. A layer of mulch about 3 inches deep will help retain the soil moisture and moderate the soil temperature. A light application of a balanced fertilizer is only needed once a year.

All Japanese maples may experience some sunburn or leaf scorch during the summer months. The green varieties take full sun better than red or variegated leaf forms, but all varieties like a little afternoon shade. The north side of a house is often a good planting location. A few years ago I planted the popular red leaf variety, 'Bloodgood', on the east side of my yard where it receives afternoon sun, and so far, it is thriving. I make sure to deep water once a week during the hot summer months and keep it heavily mulched. It does develop some leaf scorch towards the end of summer, but this in itself is not dangerous to the tree.

Pruning Japanese maples is a gardener's delight because they are slow growing and loppers or shears are all that are usually needed. In general try to prune to an open vase shape. In winter thin out entire branches if they cross over other branches or grow toward the middle of the tree. Remove excessive "twiggy" growth by cutting just beyond a pair of buds on the twig or branch. Prune only to accentuate the natural shape, and only remove branches and inside growth that obscure or detract from the graceful trunk and limb form that you desire. Japanese maples tend to grow in layers that can be pointed upward or allowed to droop depending upon the desired effect for the site. Rather than take off too much wood in winter, wait until leaf out in spring to make the finishing cuts for the final shape.

Some popular varieties are: 'Senkaki' or 'Sango-kaku' - coral colored bark with green leaves. 'Dissectum' - weeping lacy purple foliage. 'Bloodgood'-red leaves that retain color well in summer. 'Burgundy Lace' - red foliage displayed against green stems. 'Osakazuki', 'Tana', and 'Tsuma beni' - green leaves. 'Karasugawa' and 'Orido nishiki' are variegated leaf varieties. 'Filigree' - weeping variety.

You won't regret including a Japanese maple in your garden. Its lacy leaves, marvelous leaf color, and artistic trunk shape make it a truly impressive landscape feature. One to enjoy through all the seasons.

May 24, 2001