Sourwood Tree Plant Care

Sourwood Tree (Oxydendrum arboreum) belongs to the Ericaceae family within the Oxydendrum genus. Sourwood Tree is native to eastern North America, from southern Pennsylvania south to northwest Florida and west to southern Illinois. Sourwood Tree is also known as Sourwood, Sorrel Tree, Lily-of-the-Valley Tree.

Sourwood Tree displays a small deciduous tree growth habit, reaching up to 30 ft tall with a spread of approximately 20 ft. Sourwood Tree produces bell-shaped white flowers in drooping clusters.

Leaf size: approximately 6 inches.

Water a young or newly planted Sourwood Tree every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Sourwood Tree thrives in partial shade to full sun.

Oxydendrum arboreum tolerates temperatures of 50–90°F. Sourwood Tree prefers humidity levels of 40–70%.

Moist, acidic, well-draining soil with high organic matter content. Good drainage is essential for Sourwood Tree to prevent waterlogging, which leads to root rot and fungal issues.

Feed Sourwood Tree every 8 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with partial shade to full sun and moist, acidic, well-draining soil with high organic matter content. Avoid low spots where water collects after rain.

Sourwood Tree is suited to USDA Zone 5a – 9b.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

Sourwood Tree can spread to about 20 ft (6.1 m) and reach about 30 ft (9 m) tall. Space plants about 20 ft (6.1 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune Sourwood Tree while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

Sourwood Tree is hardy down to USDA zone 5a, so once established it can stay outdoors through winter in that zone and warmer ones.

Water deeply in late autumn before the ground freezes, and spread a 5–8 cm (2–3 in) layer of mulch over the root zone, keeping it away from the trunk.

Young and container-grown trees need extra protection: roots in a pot freeze much more easily than roots in the ground.

Sourwood Tree can be propagated through seeds, softwood cuttings.

See all plants toxic to cats and plants toxic to dogs.

Sourwood Tree is susceptible to spider mites, scale insects. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Sourwood Tree grows outdoors in USDA Zone 5a – 9b. It survives winters down to planting zone 5a. Sourwood Tree is native to eastern North America, from southern Pennsylvania south to northwest Florida and west to southern Illinois.