Home garden designs: Sourwood

Thursday, March 6, 2014

Sourwood

Oxydendron arboreum

A moderate growing, dense, pyramidal, small to medium sized tree native to woodlands of the eastern U.S. ( Louisiana to southern Ohio and Pennsylvania and south ) that can reach up to 30 feet or more, sometimes much larger. Some records include: fastest recorded growth rate - 4.5 feet; 1st year - 3 feet; 20 years - 40 x 20 feet; largest on record - 120 x 120 feet with a trunk diameter of 3.5 feet; largest in North Carolina - 120 feet in Robbinsville; largest in Virginia - 95 x 70 feet in Amelia Co. The Sourwood can live to as long as 263 years.
An excellent choice for a landscape specimen or underplanted in a open woodland.
The slightly wavy, finely tooth margined, elliptic leaves are pointy tipped and up to 9 x 4 inches. The foliage is bronze green at first turning to glossy deep green in summer and turns to very attractive scarlet red and purple late in autumn.
The fragrant, small, white, urn-shaped flowers, up to 0.3 inches in length, are borne in upright, spreading racemes, up to 12 inches at the branch tips during mid to late summer.
Later in autumn, the flowers are replaced with small, woody brown capsules.
The twigs are reddish and the thick bark is gray-brown, scaly and deeply furrowed.
The woods weights up to 46.5 pounds per square foot.
Hardy zones 3 to 9 the Sourwood blooms best in full sun but grows very well in partial shade. It prefers the same site conditions as Rhododendrons, preferring moist, deep, peaty, well drained acidic soil. Drought tolerant once fully established. They like their roots cool so mulching with shredded oak leaves or pine needles is recommended plus the fact that root competition from turf can stunt growth. The Sourwood does not like transplanting and is likely to grow very slowly until finely becoming established. It is not hardy north of zone 6 for the first few winters so in those climates approapriate winter protection should be given until the plant hardens. Free of pests or disease.
Smaller trees transplant much better. Propagation is from seed in autumn or softwood cuttings taken in summer as well as tissue culture. Seedlings which are normally slow, grow like weeds under florescent light. Root prune seedlings to make transplanting easier later on.

* photos taken on July 2 2010 in Columbia, MD