White birch (betula papyrifera) is also known as paper birch and canoe birch, for its characteristic white papery bark. The domestic white birch tree grows 40 to 50 feet in height on a 12- to 24-inch trunk and forms an open, narrow, round-topped head. Its leaves turn yellow in autumn. White birch is recommended as an urban substitute for aspen trees in Colorado because of their similar appearance. White birch trees planted in Colorado's U.S. Department of Agriculture Hardiness Zones 4, 5 and 6 respond well to standard birch tree care.
White birch trees have a shallow root system that makes them sensitive to drought or unusual heat in the soil. According to the U.S. Forest Service website, "Homeowners should attempt to place birch trees in locations where the soil will be shaded, cool, and moist." Birch trees also need full to partial sunlight, which is often found on the east and north sides of the house. Do not plant a birch tree under overhead power lines. The white birch thrives in Colorado soil with pH 5.0 to 6.5, which is slightly acidic. Soil with high organic content benefits the white birch.
Soil should be professionally tested before beginning a fertilizing program. The Colorado State University soil testing lab conducts routine pH analysis tests as well as testing for organic content, electrical conductivity and analysis of macronutrients. Birch trees in Colorado do not need to be fertilized unless they lack any of the 17 essential nutrients needed for healthy tree growth. When fertilizer is needed, it should be applied in late fall or early spring, according to individual package recommendations. Backyard compost is a balanced fertilizer that contains all essential nutrients and can be used without concern for chemical toxicity.
White birch trees in Colorado may need soil protection around their trunk base. A 3- to 5-inch layer of mulch keeps soil cool in summer and warm in winter. Mulch layers of shredded bark or composted leaves conserve water, reduce resource competition from weeds, reduce soil compaction and add organic matter to soil. Placing mulch around the birch tree base also reduces the probability of damage from weed trimmer strings. Avoid direct contact with the tree trunk when placing mulch in a diameter around the tree.