Although not as popular as white paper species, clump river birch holds several advantages as a landscape plant. Clump river birch grows 40 to 70 feet tall and forms up to five trunks. The cinnamon-colored bark peels off in strips to reveal gray, lavender and orange inner bark. The silvery foliage flutters with the slightest breeze and provides dappled shade. Clump river birch is difficult to transplant but resists pests and tolerates heat. Use the best care practices to ensure establishment.
Things You'll Need
- Soaker hose
- Garden fork
- Pruning saw
- Iron supplements
Plant clump river birch in a sunny location that provides afternoon shade to cover the roots. Clump birch prefers rich, sandy soils with 4.5 to 7.5 pH level.
Water the tree after spring flowering and before the sap bleeds. Place a soaker hose around the drip line of the tree. Allow the water to penetrate the soil to a depth of 2 to 3 feet. Provide water every two to three weeks throughout the growing season.
Spread a 3- to 4-inch layer of wood chip or peat moss mulch around the base of the tree. Keep a 3-inch gap between the mulch and the tree to avoid rot. The mulch conserves water loss, keeps the root system cool and suppresses weed growth.
Aerate heavy soils during the second spring season. Create a grid of aeration holes that extends from the base of the tree to just beyond the drip line. Use a garden fork or power drill to dig the holes. Space the holes 7 to 8 inches apart.
Apply fertilizer to the aeration holes to avoid direct contact with the roots. Use an acidic, evergreen fertilizer with a 30-10-10 analysis. Follow label instructions for dosage amounts.
Prune clump river birch after the leaves reach mature size in late spring, using a pruning saw. Cut limbs just outside the branch bark ridge - the swollen point where the branch joins the trunk - to protect the branch collar. If you make the cut too far from the branch bark ridge, the limb stub will not properly heal. If you make the cut too close to the branch collar, you risk injuring plant tissue.
Monitor clump river birch foliage for disease. Anthracnose leaf blight presents water-soaked spots and dead tissue on foliage, but affected trees respond to fungicide applications. Clump river birch develops an iron deficiency that causes yellow foliage when the soil's pH level is too high. Counter the deficiency with supplemental iron treatments via soil application, trunk injection or foliar spray, per label instructions.
- University of Saskatchewan Extension; Guide to Birch Trees; Russel Friesen; 1995
- USDA; River Birch; John Dickerson and Lincoln Moore;
- University of Wisconsin Cooperative Extension; Common Foliage Diseases of Shade Trees …; G.L. Worf, et al.; 1997
- Utah State University Cooperative Extension; Preventing and Treating Iron Chlorosis in Trees and Shrubs; Michael Kuhns, et al.; 2003
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