Oxydendrum arboreum

Common Names

Sourwood, Sorrel Tree, Lily-of-the-Valley Tree

Summary

Sourwood is a deciduous tree native to the eastern and southeastern United States with a pyramidal to oval form, slender trunk, and drooping branches. It grows slowly to about 25–30 ft tall and 15–25 ft wide, with alternate, simple, glossy green leaves 3–8 in long that turn brilliant red to crimson in fall; the tree bears fragrant white urn-shaped flowers in midsummer arranged in drooping panicles, followed by small brown capsules that persist into winter; the gray-brown bark is deeply furrowed, and the leaves have a sour taste due to oxalic acid, adding to its distinctive character and making it a prized focal specimen for ornamental landscapes and pollinator-friendly plantings in zones 5–9.

For cultivation, it prefers acidic, moist, well-drained soils and performs best in full sun to partial shade; flowering and fall color are best in sun, and it is drought-intolerant and sensitive to urban pollution and alkaline soils. Transplantation is easier when young, container-grown stock improves establishment, and regular irrigation is helpful in hot, dry weather. It is commonly used as a specimen or border plant in landscapes, valued for nectar for bees and the resulting sourwood honey. Propagation is primarily by seed, cuttings root poorly, and micropropagation is possible; pests and diseases are usually not serious, though twig blight and leaf spots may occur, and pruning is minimal to maintain a healthy framework.

Lifecycle

Perennial

Height

20-30 feet

Spread

20-30 feet

Hardiness Zones

Zones 5-9

Sunlight Requirements

Ideally full sun; tolerates partial sun and partial shade.

Soil Type

Acidic, well-drained, moist soil, pH 3.7–6.5, rich in organic matter

Soil Drainage

Well-drained, moist, acidic soil

Soil pH

3.7-6.5

Bloom Color

White

Bloom Time

Spring to Summer

Foliage Color

Green in summer; crimson-red to dark purple in fall.

Fall Foliage Color

Red, Purple, Yellow, Orange

Leaf Lifecycle

Deciduous

Growth Rate

Slow

Seasons of Interest

Summer and Fall

Propagation Methods

Seeds and Cuttings, Micropropagation / tissue culture

Attracts Wildlife

Attracts bees and other pollinators