Persian Ironwood
Leaf emergenceParrotia persica
Hamamelidaceae · broadleaf deciduous tree · introduced
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Parrotia persica (Hamamelidaceae) is a deciduous tree or large shrub native to northern Iran and Azerbaijan. It grows 20 to 40 feet tall with a rounded, spreading crown and exfoliating bark that reveals a mosaic of gray, green, white, and brown. Dark red flowers consisting mostly of stamens appear on bare branches in late winter to early spring before the foliage emerges. Fall color is exceptional, ranging through yellow, orange, red, and purple, often with multiple colors on a single tree.
Persian ironwood thrives in full sun to part shade on well-drained soil across a range of soil types. It is notably pest- and disease-free, with no significant problems documented. The species tolerates moderate drought once established. Growth rate is moderate. It is valued as a four-season specimen tree for its winter flowers, summer foliage, fall color, and winter bark display. Hardy in Zones 5a to 8b.
Field Observations
Quick Facts
Phenological Calendar
As of April 28, 2026, Puget Sound stations range from 1536.6 to 1694.7 GDD₃₂. Persian Ironwood has passed leaf emergence (958 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 28, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,695 | Leaf emergence | — | — |
| Seattle / UW | 1,654 | Leaf emergence | — | — |
| Kent / Auburn | 1,644 | Leaf emergence | — | — |
| Olympia / Tumwater | 1,603 | Leaf emergence | — | — |
| Bellingham / Whatcom | 1,591 | Leaf emergence | — | — |
| Tacoma / Puyallup | 1,572 | Leaf emergence | — | — |
| Sequim / Rain Shadow | 1,537 | Leaf emergence | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ● Leaf emergence BBCH 10 NOW | 958 | Mar 15-Mar 30 |
| Leaf expansion BBCH 12 | — | Mar 25-Apr 10 |
| Leaf senescence / fall color BBCH 93 | — | Oct 15-Nov 15 |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? Hover over GDD values for source details. Season tracker for Kent / Auburn as of Apr 28, 2026. Predicted dates use 16-day weather forecast through May 14, 2026, then climate normals.