Are Maple Trees Suitable for the Space Between a Sidewalk & a Curb?

Drip Line

• One of the keys to understanding the size of a particular maple species' root space is to think of its drip line. The drip line is an imaginary circle drawn on the ground that is equivalent to the circumference of the tree's crown -- the branches and leaves at maturity. Major lateral roots go out to at least the edge of the drip line and often further. A mature red maple (Acer rubrum), hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9, has a spread of at least 30 feet, the diameter of the drip line.

Narrow Planting Strips

• If planting strips are narrower than 3 feet wide, it is unlikely that most trees will have enough root space to thrive. Strips that are 4 feet wide can accommodate small maples like Japanese maple (Acer palmatum), generally hardy in USDA zones 5 or 6 through 8. There are a wide variety of available cultivars, with many leaf configurations, growth habits and mature sizes. "Butterfly" (Acer palmatum "Butterfly") for example has an upright habit, attractive variegated leaves and good fall color. Its mature height is 12 to 15 feet, with a spread of 6 to 8 feet.

Wide Planting Strips

• For most other planting strips that are 6 feet wide or more, select small to mid-size maples, like Tatarian maple (Acer tataricum), hardy in USDA zones 3 through 8. The tree grows 18 to 20 feet in height with a similar spread, often with good fall leaf color. Another good choice is trident maple (Acer buergerianum), hardy in USDA zones 5 through 8 or 9. The trident-shaped leaves are bronze when young, ripening to green and finally to red or yellow in the fall. The tree grows 20 to 30 feet tall.

Legal and Practical Considerations

• In many municipalities, the strip between sidewalk and curb is a right of way that is administered by the municipality. Before making plans to plant a maple or any other kind of tree in the strip, consult local authorities about any pertinent rules and regulations. Sometimes tree selection is governed by a municipal arborist or shade tree commission. In situations where planting strips are too narrow for a substantial maple, the tree can sometimes be planted on the other side of the sidewalk. This gives larger trees good root runs and maintains the shade tree canopy.