Maples adapt to a wide range of cultural situations. This allows them to adjust to the needs of various companion plants. Their roots are not invasive, so they are compatible with most plants. Maples prefer a spot out of strong wind, especially the laceleaf cultivars. Green and red cultivars will take full sun very well. Some variegated cultivars and maples in containers prefer some afternoon shade. Provide consistent moisture and good drainage for your maples. Overwatering is detrimental. Trees planted in the ground need extra attention the first year before the roots become established in the native soil. (See Watering the Rootball). In heavy and poor soils you can mix some medium size fir bark in with the native soil. No peat moss. You can also ‘mound plant’ your maple. Maples are light feeders. One application in the spring is enough. In the container, maples need a fast draining potting mix. Do not mix with large amounts of peat moss. We use Pro Gro #9B or #9BF which is around 75% bark and15% pumice, 10% peat moss. Let the soil mix dry a little before watering. Again, overwatering is detrimental. Repot in early spring for the first 2 or 3 years into a pot one size larger. Always prune any circling roots, and make a few cuts with clippers to the bottom and sides of the rootball. After 3 years the size of the tree will determine the pot size. Winter protection is needed for the rootball in below freezing temperatures. Vigorously growing cultivars will sometimes produce whole branches of atypical foliage. The typical foliage will appear on this wood the next year. If it does not produce normal foliage the next year, the branch may be reverting and you may need to remove it. Dormant season pruning should be done in late winter. Never prune when the buds begin to swell and new leaves are just expanding. One of the best times to prune in the NW is in the summer. Pruning at this time of the year reduces the potential for disease infection. It also reduces the potential for sucker response. If you would like your maple to remain small cut back any long whips by half at mid-summer after new growth has stopped.

Remember that all the roots are inside the newly planted rootball. As water is withdrawn by the plant, the rootball may shrink slightly leaving a small crack surrounding the rootball. If a rootball containing coarse textured media is planted into a fine texture soil, plants are often lost merely from desiccation. Changes in media texture such as from coarse to fine or the reverse, act as major obstacles to water movement. The surrounding soil may be soggy wet and the rootball may remain totally dry. Until roots move out of the existing rootball, all water taken up by the plant must come from the small planted ball---water the rootball and ignore the surrounding soil. You can build a watering basin around the rootball to help in watering, but remove or widen it after one season.

Bibliography:
Vertrees, J.D. Japanese Maples
Dave Adams, OSU Extension Service