Seven Sons Flower
Heptacodium miconioides
Caprifoliaceae · broadleaf deciduous shrub · introduced
Last updated
Data Coverage 3 of 6 dimensions
Quick Facts
Height
15–25 ft
Light
Full Sun to Shade
Hardiness
Zone Zones 4–5
Bloom Time
September
Origin
central and eastern China, but apparently it is rather rare
Phenological Calendar
As of April 19, 2026, Puget Sound stations range from 1342.9 to 1500.8 GDD₃₂. Seven Sons Flower typically reaches 'first bloom' at 4870 GDD₃₂, predicted around Aug 16.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 19, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,501 | Pre-season | 'First bloom' | 3,369 |
| Seattle / UW | 1,465 | Pre-season | 'First bloom' | 3,405 |
| Kent / Auburn | 1,441 | Pre-season | 'First bloom' | 3,429 |
| Olympia / Tumwater | 1,415 | Pre-season | 'First bloom' | 3,455 |
| Bellingham / Whatcom | 1,390 | Pre-season | 'First bloom' | 3,480 |
| Tacoma / Puyallup | 1,381 | Pre-season | 'First bloom' | 3,490 |
| Sequim / Rain Shadow | 1,343 | Pre-season | 'First bloom' | 3,527 |
| Stage | GDD32 | Typical Window |
|---|---|---|
| ○ 'First bloom' BBCH '61' NEXT | 4870 | '' est. Aug 16 (avg) |
| 'Full bloom' BBCH '65' | 5450 | '' est. Sep 3 (avg) |
Range: 4528–4926 GDD₃₂
(6yr)
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 19, 2026. Predicted dates use 16-day weather forecast through May 5, 2026, then climate normals.