Black Walnut
'Flower buds visible'Juglans nigra
Juglandaceae · broadleaf deciduous tree · introduced
Last updated
Plant Profile
Size & Form
Height
100 ft
Spread
65 ft
Growth Rate
Fast
Size at 20 yr
35 ft
Lifespan
Moderate
Site Requirements
Light
Full Sun
Soil Drainage
Well Drained
Soil pH
4.6-8.2
Water
High
Drought Tolerance
Low
Hardiness
Zones 4a–8b
Ornamental Interest
Bloom Time
May to June
Fall Color
Yellow, insignificant
Origin
Massachusetts to Florida, west to Minnesota and Texas
Watch for this season
Fall webwormHigh
Larval Feeding & Web Building
Anthracnose (Shade Trees)Moderate
Active Infection & Secondary Spread
Phytophthora Root RotModerate
Growing Season Stress Expression
Crown GallMonitor
Dormant in Soil
Diseases: Regionally Documented (10)
Discula destructiva (dogwood), Kabatiella and Discula spp... Anthracnose Black Walnut Toxicity Rhizobium radiobacter (formerly Agrobacterium tumefaciens) Crown Gall Pseudomicrostroma juglandis (syn. Microstroma juglandis) Downy Leaf Spot Mosses and Lichens Phytophthora spp. (P Phytophthora Root Rot Geosmithia morbida (vectored by Pityophthorus juglandis) Thousand Cankers Disease Blackline virus Blackline Pratylenchus penetrans (primary) and P Nematode, Root-lesion Xanthomonas arboricola pv. juglandis Walnut Blight
Pests: Regionally Documented (6)
Phenological Calendar
As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Black Walnut has passed 'flower buds visible' (1671 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,673 | 'Flower buds visible' | — | — |
| Kent / Auburn | 2,665 | 'Flower buds visible' | — | — |
| Seattle / UW | 2,610 | 'Flower buds visible' | — | — |
| Olympia / Tumwater | 2,570 | 'Flower buds visible' | — | — |
| Tacoma / Puyallup | 2,535 | 'Flower buds visible' | — | — |
| Bellingham / Whatcom | 2,533 | 'Flower buds visible' | — | — |
| Sequim / Rain Shadow | 2,436 | 'Flower buds visible' | — | — |
View full calendar (3 stages)
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Bud break' BBCH '07' | 1410 | '' |
| 'Leaf emergence' BBCH '11' | 1526 | '' |
| ● 'Flower buds visible' BBCH '51' NOW | 1671 | '' |
Source: 'NPN citizen science observations (WA+OR), n=7, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.
Data Maturity Structured Multiple sources. Expert review underway.