The Arizona sycamore (Platanus wrightii) is a large shade tree valued for its distinctive, exfoliating bark that becomes ghostly white in winter and attractively mottled in warmer weather. In the home garden, this southwest native needs plenty of room to grow; the largest specimen measures more than 70 feet wide and tall. Sycamores need a dependable source of water to support this growth, something not common in high or low deserts of Arizona. However, the Arizona sycamore, as a riparian tree, has found a niche along rivers descending from the Mogollon Rim. The large network of shallow roots gives the tree an advantage in this habitat, but the same root system may cause trouble in the landscape.
Select the Arizona sycamore to be planted. The tree should be healthy; carefully examine the roots. Never buy a tree with circling roots or with roots pushing out through the container's drainage holes. Also check the upper limb structure; avoid trees with many crossing or ill-shaped branches, or with branches that angle awkwardly from the trunk. These will grow into weak limbs if allowed to remain on the tree.
Choose the planting location. Both the roots and branches will need plenty of room; never plant a sycamore near a house or where the roots will heave up sidewalks or driveways. Arizona sycamores also prefer full sun and need 6 to 8 hours of sun to be healthy. Because of its riparian nature, plant a sycamore where it will receive water year-round.
Dig the planting hole twice as wide as the tree's container, placing the excavated dirt on a tarp or in a wheelbarrow. Do not dig too deeply; a tree will settle after planting, and covering the original surface with either standing water or new soil can smother the tree's roots and encourage disease.
Remove the tree carefully from the container. Do not pull on the branches of the sycamore. Loosen the roots carefully, and untangle any circling roots, cutting them with pruning shears if necessary. Roots that circle will continue to grow tightly around the tree, delaying the tree's establishment and even girding it.
Place the tree in the hole. Add the excavated soil under the base of the tree to lift it slightly above the original ground level to compensate for future settling. Refill the planting hole with the original dirt. Adding compost or other soil amendments is no longer recommended, according to M.A. Powell, horticultural specialist at North Carolina State University, unless the soil drains extremely fast or is exceptionally poor. Fill the planting hole roughly two-thirds full, then gently shift the new tree up and down to settle and straighten it.
Continue to pack dirt firmly around the new planting. If the Arizona sycamore is very small or exposed to strong winds, it may be staked. However, staked trees do not form wide, strong trunks as quickly as unstaked trees. Create a watering basin with extra soil, spread 2 to 3 inches of mulch around the base and then water deeply.