Sourwood, Oxydendrum arboreum
2024 October Plant of the Month
Northern Neck Chapter of the Virginia Native Plant Society

Photos and Text by Betsy Washington

*Sourwood’s outstanding fall color highlights the panicles of pale-yellow fruit capsules creating a fall show*

The October Plant of the Month, Sourwood or Lily-of-the-Valley Tree, is spectacular in every season but especially so each fall as the foliage ignites into brilliant crimson or reddish-purple. Sourwood is one of our earliest, most vivid, and most reliable fall coloring trees, especially in the South. This small to medium sized deciduous tree is often an understory tree but can reach up to 60’ or higher. In fact, the record Sourwood growing near the Roanoke River in Virginia towers to 95’ tall with a 3’ diameter trunk! Although Sourwoods naturally occur from Pennsylvania south the Florida and west to Ohio, in Virginia, they are found in all provinces from the coastal plain to the Appalachians but are most common south of the James River becoming less frequent to the North. Alas, Sourwoods are not found in the northernmost counties of Virginia. Although they inhabit a wide variety of habitats, they require acidic soils and often occur with Oaks and other acid loving plants on moist slopes just uphill from bottomlands

*The lightly fragrant June and July blooms resemble Lily-of-the-Valley blooms dangling from branch tips*

Although Sourwoods are stunning in fall, they are beautiful in every season. They typically have a graceful pyramidal habit to 20 – 30’ high and are branched to the ground, especially when grown in the open. Their silky leaves are lustrous green in summer and elliptic in shape, resembling peach leaves, but with very fine teeth along the margins. Taste them and you will understand where the common name “sour “wood comes from! From June into July incredibly showy white “lily-of-the-valley” flowers cascade from nearly every branch tip like a lacy veil. Individual flowers are urn-shaped and held in branching panicles that may reach up to 10” long and droop gracefully in an incredibly beautiful display. But the show doesn’t stop here! The seed capsules turn a light creamy yellow and persist for months. By September they are particularly striking against the crimson fall foliage, almost out-shining the summer floral extravaganza. Even in winter Sourwood’s picturesque habit continues the show with its distinctive blocky, deeply fissured gray bark and chains of dry seed capsules dangling from the canopy.

Sourwoods are members of the Blueberry or Rhododendron (Heath) family and like other members grow best in moist but well drained acidic, peaty soils. In a garden setting they will grow in full sun to part shade but prefer some protection from the hottest afternoon sun. They are even moderately tolerant of salt but do not tolerate pollution, root disturbance, or extremely dry or compacted soils; thus, are not well suited to urban conditions. Sourwoods are difficult to transplant and are best planted as a small container specimen. They can also be grown from seed and will bloom in 5 years. Like other members of the blueberry family, they rely on mycorrhizal fungi that have evolved with members of the Heath family and that functionally extend the root systems and help obtain nutrients and water in the acidic soils where they grow, while protecting them from pathogens. If you already have Lowbush Blueberries or Mountain Laurels growing on your property, Sourwoods will probably thrive too. Allow the fallen leaves to form a natural mulch around your tree or add organic bark or wood chips to encourage and feed the tree and its fungal partners.

Beautiful whether planted as a striking specimen tree or in naturalistic groups along a woodland edge, Sourwoods will certainly win your heart and take center stage in the landscape. The lightly fragrant flowers attract a variety of pollinators making this an unusual but striking tree for a pollinator garden. Honeybees produce a highly-prized honey from sourwood nectar. As an added bonus, Sourwoods are relatively deer resistant.

Keep an eye out for this stunning tree along woodland edges, road cuts or in acidic woodlands this fall and prepare to fall in love! You may well decide that you must have this wild beauty in your own garden, especially if you have the acidic woodsy soil, it thrives in.

Plant of the Month October 2024: Sourwood