Sourwood

Oxydendrum arboreum

Slow-growing eastern North American native tree with pendant sprays of small white bell flowers in midsummer and brilliant crimson autumn colour. The dual-season indicator of southern Appalachian forests.

Hardiness ratings

Sourwood hardiness across the four zone systems
SystemRatingTemperature rangeHow to read it
USDA hardiness zone Zone 5–9 −28.9 °C to −1.1 °C Plant tolerates down to this zone
RHS hardiness rating H6 −20 °C to −15 °C Plant needs at least this level of cold tolerance
Canadian plant hardiness zone Zone 5–8 −23 °C to −1 °C Plant tolerates down to this zone
Australian (ANBG) zone Zone 2–5 −10 °C to 10 °C Plant tolerates down to this zone

Growing notes

  • Brilliant deep crimson autumn colour October — one of the most reliable native autumn-colour trees of the eastern US
  • Lily-of-the-valley-like white bell flower sprays in July — a secondary midsummer feature and a source of the famously fine sourwood honey
  • Strictly an acid-soil plant — chlorotic on alkaline soils
  • Slow growing — eventually a small to medium tree

Categories

Related plants

Cross-check Sourwood against your zones

Reference

Sourwood on Wikipedia