Tuliptree
Liriodendron tulipifera
Magnoliaceae · broadleaf deciduous tree · native
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Liriodendron tulipifera (Magnoliaceae) is a fast-growing deciduous tree native to eastern North America. It is one of the tallest eastern hardwoods, reaching 120 feet tall and 39 feet wide, with about 50 feet of growth in the first 20 years. The distinctively shaped leaves have four lobes and a flat or notched apex. Tulip-shaped yellow-green flowers with an orange band at the base appear in May to June but are often obscured by foliage on mature trees.
Tuliptree adapts to a range of soils but prefers moist, slightly acidic conditions (pH 4.5 to 6.5) in full sun. Bloom begins around 490 to 509 GDD (base 50 F). The tuliptree aphid is a serious pest, producing copious honeydew that leads to sooty mold on anything beneath the canopy. Verticillium wilt is also documented. Cultivars include 'Fastigiatum' (columnar), 'Aureo Marginatum' (yellow-edged leaves), and 'JFS-Oz' (compact). It is the official state tree of three U.S. states. Hardy in Zones 5a to 8b.
Quick Facts
Phenological Calendar
As of April 23, 2026, Puget Sound stations range from 1434.4 to 1592.7 GDD₃₂. Tuliptree typically reaches bloom start at 1862 GDD₃₂, predicted around May 9.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 23, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,593 | Pre-season | Bloom start | 269 |
| Seattle / UW | 1,554 | Pre-season | Bloom start | 308 |
| Kent / Auburn | 1,537 | Pre-season | Bloom start | 325 |
| Olympia / Tumwater | 1,505 | Pre-season | Bloom start | 358 |
| Bellingham / Whatcom | 1,483 | Pre-season | Bloom start | 379 |
| Tacoma / Puyallup | 1,472 | Pre-season | Bloom start | 390 |
| Sequim / Rain Shadow | 1,434 | Pre-season | Bloom start | 428 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ Bloom start BBCH 61 NEXT | 1862 | Apr 1-Apr 30 est. May 9 (forecast) |
| Full bloom BBCH 65 | 1934 | — est. May 13 (avg) |
| Bud break BBCH 07 | — | Feb 15-Mar 15 |
| Leaf emergence BBCH 11 | — | Mar 1-Apr 1 |
| Bloom end / petal fall BBCH 69 | — | Apr 15-May 15 |
| Fruit/seed development BBCH 71 | — | Jun 1-Aug 31 |
| Fall color / leaf senescence BBCH 93 | — | Oct 1-Nov 15 |
| Dormancy BBCH 97 | — | Nov 15-Feb 28 |
GDD = Growing Degree Days (base 32°F, Jan 1 start). Why base 32? Source GDD₅₀ thresholds from Herms 2004 (OSU, Secrest Arboretum, Ohio) and UMD IPMnet (Gill & Klick, mid-Atlantic), converted to GDD₃₂ via Kent bloom-date mapping. Season tracker for Kent / Auburn as of Apr 23, 2026. Predicted dates use 16-day weather forecast through May 10, 2026, then climate normals.