Oxydendrum: The Sourwood Tree
Sourwood is one of many trees to provide shades of gold, scarlet, and purple every autumn. Lacy strands of creamy berries show against the coloring leaves as well, adding a graceful texture in the garden.
Plant care & info
Family: Ericaceae (Heather & Rhododendron family)
Genus: Oxydendrum (ox ee DEN drum). In Greek, oxy means acid, Dendron means tree.
Common Name: Sourwood Tree, Lily-of-the-Valley Tree, or Sorrel Tree
US native along stream banks in Virginia, North Carolina, Pennsylvania, Ohio, Kentucky, and Tennessee.
Prefers sun to part shade and acidic, peaty soil. It will grow best without lawn or ground cover at the base, as it doesn’t like to compete for nutrients and water. Mulching is a good idea, and summer watering is important. Zone 5.
City trees are usually about 25-30′ at maturity. In its native habitat, Sourwood can grow up to 60′ tall.
Sourwood prefers moist, acidic soil, which we certainly have in Portland, but it dislikes our heavy soils. Drainage is important, so amending soil in the planting bed is key. Soil should be blended into as wide an area as possible, as the roots will spread out horizontally from the trunk.
Trees without good soil drainage may develop leaf spot. Trees planted in lawns are likely to experience more branch die-back and to linger rather than thrive.
Sourwood is equally at home as a center piece or natural planting, and it is small enough to fit most city yards!
Only one species exists, Oxydendrum arboreum. August blooming flowers are creamy white bells held on chains. Pointed, oval leaves emerge green, turning bright yellow, red, and purple in fall before dropping. Fruit is creamy yellow and shows against the leaves as they change color into fall. Bark looks like gray alligator skin. The tree is upright with a round head & slow-growing.
