In the Garden:
Northern California Coastal & Inland Valleys
Elegant foliage makes the Japanese maple a favorite landscape tree.
We are in the process of redoing the landscaping at the KRON building on Van Ness Avenue in San Francisco. Money being tight these days, I was asked to suggest plants that might do well on the windy boulevard. The building was surrounded by overgrown juniper and ceanothus -- plants that are hardy but that don't provide much color. Also, those plants had been badly pruned over the years and had a woody, neglected look.
We decided on lantana as the trailing ground cover, which does well anyplace there is sun, regardless of watering, weather, or soil conditions. Tibouchina was selected for its brilliant purple flowers that last for many months and for its tolerance to the San Francisco fog. We also decided on Japanese maples for their elegant form, exquisite foliage color, and forgiving nature.
Japanese maple (Acer japonicum and A. palmatum) require partial shade, regular water, and fast-draining, rich soil, all of which we can provide in the large planting beds outside of the building. The finely cut, lacy leaves and low, round shape of the trees will compliment the granite walls.
Luckily, we had recently shot a segment about Japanese maples with the Bartlett Tree Experts, who told us that not all of these elegant little trees are created equal. Some maples grow upright and some have the round shape we were looking for. The coral bark maple (A. palmatum 'sangu kaku'), for example, is not an especially nice-looking specimen during the growing season, but when it loses its leaves in the fall, the magnificent red bark more than makes up for the rest of the year.
Plant Where Azaleas Thrive
Wherever azaleas and rhododendrons thrive, so will these hardy little trees. Most Japanese maples grow slowly to 20 feet high and wide, depending on the variety. It's very important to do your homework prior to selecting a Japanese maple tree. They are expensive to purchase, and their shape when young is the shape they will always be. You can't train a Japanese maple to conform to your idea of what it should look like. Tip pruning is acceptable to keep the plants from getting leggy, and of course all plants need annual grooming to remove dead, diseased, or injured wood. But if you think that you can turn an upright-growing variety into a round shape, you will be very disappointed. Use a resource such as the Sunset Western Garden Book to select a tree. If possible, go to a nursery that specializes in maples, such as Wildwood Farm (http://www.wildwoodmaples.com).
Japanese maples do well in containers, too. Just make sure the pots are large enough to accommodate the roots and that the soil is fast-draining. Use mulch to cool the soil and preserve moisture.
Maples don't have many disease or insect problems. Occasionally, aphids will feed on tender new growth. Scale insects and mealybugs also can be a minor problem, but trees that are grown in ideal environments are usually healthy. Wind can be a problem and can desiccate the delicate foliage. Also, if the trees are planted near heat-reflecting surfaces, such as driveways or sidewalks, the foliage may become burnt or crispy.
Care and Feeding
Plant Japanese maples high in the soil. The top 1 inch of the rootball should be visible above the ground. This planting technique will facilitate drainage. All slow-growing plants are light feeders, maples included. Liquid fish emulsion applied several times during the growing season will suffice. Apply cottonseed meal around the drip line in early spring as a source of nitrogen.
Ideally, the soil should never dry out completely. If you notice dry tips on the foliage, inadequate moisture is most likely the cause. Fall and winter are ideal times for planting deciduous maple trees. They will adjust to their new environment better than if planted in the spring or summer months.
Prepare yourself for serious sticker shock; it's not uncommon for mature desirable varieties, such as A. palmatum 'Dissectum', to run into the hundreds of dollars.
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