Sourwood Lily-of-the-Valley Tree

Oxydendrum arboreum

Ericaceae · broadleaf deciduous tree · introduced

Last updated March 9, 2026

Data Coverage 2 of 6 dimensions

Site Data

Threats

Cultivars

Phenology

GDD Thresholds

Puget Sound

Quick Facts

Height

25–30 ft

Spread

19 ft

Growth Rate

Slow

Light

Part Shade

Soil

Well Drained

Water

Low

Hardiness

Zone Zones 6a–9b

Bloom Time

June to July

Fall Color

Purple, red, yellow

Origin

Virginia to North Carolina, Pennsylvania

Stage	Typical Window	What to Look For
Bud break BBCH 07	Feb 15-Mar 15	Buds swelling and beginning to open; first green tissue visible
Leaf emergence BBCH 11	Mar 1-Apr 1	First leaves fully unfurled on new growth
Bloom start BBCH 61	Jun 1-Jun 30	First open flowers visible; flowers white
Bloom end / petal fall BBCH 69	Jun 15-Jul 15	Last petals falling; flower structures fading
Fruit/seed development BBCH 71	Jun 1-Aug 31	Fruit or seed structures forming; fruit color: brown
Fruit/seed maturity BBCH 85	Sep 1-Nov 30	Fruit fully colored and ripened; seed dispersal may begin
Fall color / leaf senescence BBCH 93	Oct 1-Nov 15	Leaves changing color; fall display beginning
Dormancy BBCH 97	Nov 15-Feb 28	Leafless; no active growth; dormant buds set