The Sourwood Tree
As autumn nears we begin to look for mornings to chill & leaves to brighten. Sourwood is one of many trees to provide the gold, scarlet & purple that dots our neighborhoods in fall. Lacy strands of creamy berries show against the coloring leaves as well, adding graceful texture.
Sourwood is equally at home as a center piece or natural planting & is small enough to fit most city yards.
Characteristics: Just one species exists, Oxydendrum arboreum. Flowers are creamy white bells held on chains & blooming in August. Pointed oval leaves are green & turn bright yellow, red & purple in fall before dropping. Fruit is creamy yellow & 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
Family: Ericaceae – The Heather & Rhododendron family
Genus: Oxydendrum (ox ee DEN drum) – In Greek, oxy means acid, Dendron means tree.
Common: Sourwood Tree, Lily-of-the-Valley Tree or Sorrel Tree
Origin: US native - Virginia, North Carolina, Pennsylvania, Ohio, Kentucky, Tennessee – grows along stream banks
Size: City trees are usually about 25-30' at maturity. In its native habitat Sourwood can grow up to 60' x 100'.
Culture: Sun to part shade. Likes acidic peaty soil & grows best without lawn or groundcover at the base because it doesn't like to compete for nutrients & water. Mulching is a good idea & summer watering is important.
Hardy Z5, -20f
Problems: Sourwood prefers acidic moist 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. Compost should be blended into as wide an area as possible, as the roots will spread out horizontally from the trunk.
Sourwood doesn't like to have plants underneath. It doesn't compete for nutrients & water well, so it should just have a layer of mulch at the base.
Trees without good soil drainage may develop leaf spot. Trees planted in lawns are likely to experience more branch die-back & to linger rather than thrive.