The Japanese maple, or Acer palmatum, is an ornamental tree prized for its bark, form and foliage of various shapes and colors. Most Japanese maple cultivars are small trees that feature brilliant leaf colors in spring and fall. Although Japanese maples are typically considered low maintenance if planted in an ideal location, they may still require waterings during hot, dry conditions or if they are grown in a container.
During Hot Weather or Droughts
Keep the soil around the tree moist throughout hot summers. Thoroughly water the top foot of soil during especially dry periods. Water at a slow rate around the tree's dripline. During hot weather, the tree may require irrigation twice per week or more. Increase the amount of available water if the tree shows symptoms of underwatering.
Symptoms of Underwatering
If the Japanese maple does not receive adequate water, the leaves will scorch, or develop brown or tan dead areas between leaf veins. The scorch may not be evenly distributed around the canopy. Increase the amount of water the tree is irrigated with. If increased watering does not alleviate the scorch, the tree may have an infected or inadequate root system.
Watering Throughout the Year
Water Japanese maples until the ground freezes. This is especially important during the fall after you plant the trees. Try to plant the maple at least four weeks before the ground freezes. If the spring is especially damp and hot, lower watering frequency to avoid fungal problems.
Watering in Containers
Container-grown trees typically require more frequent waterings than maples planted in the ground. During especially hot weather or periods of drought, the tree will probably require multiple waterings per week. Monitor closely for early symptoms of scorch and increase irrigation as needed. Consider moving the tree to a cool shaded location during especially hot or dry periods. Always make sure that a container permits proper drainage.
If planted in a proper location, a well-established Japanese maple may require no supplemental water. This plant performs best in a moist, well-draining, acidic soil with ample organic matter. The tree can grow in clay soils if the ground is sloped to permit drainage. Several inches of mulch around the tree typically improves tree performance.