Red Maple
'Leaf emergence'Acer rubrum
Sapindaceae · broadleaf deciduous tree · native
Last updated
A fast-growing deciduous tree native to eastern North America from Canada to Texas, reaching 68 feet. One of the first maples to bloom, producing small red flowers (the source of the common name) before leaves emerge in late winter to early spring, giving the tree a reddish haze. Bark is smooth and light gray on young trees, becoming dark, rough, and furrowed with age. Leaves are relatively small for a maple, usually three-lobed with serrated margins. Fall color ranges from green-yellow to brilliant orange and red, often among the first trees to turn. Native habitat spans swamps, uplands, and occasionally dry hillsides and sand dunes.
Hardy to Zone 2a. Sun to part shade. Prefers moist, slightly acidic soils (pH 4.7 to 7.3) and tolerates wet soils, including rain garden placement. High water needs. Fast growth. Low maintenance. Develops pronounced surface roots that can lift pavement. Tolerates urban conditions and black walnut proximity. Five cultivars: 'Autumn Spire' (50 feet, male/seedless, deep red fall color, Zone 3), 'Bowhall' (very narrow, 15 feet wide, yellow-orange to red, Zone 4), 'October Glory' (PP2116, brilliant orange-red, rounded, 35 feet, Zone 4b), 'Red Sunset' (PP7803, consistent red, broadly pyramidal, 40 to 50 feet, Zone 4), and 'Redpointe' (PP16769, improved branching, 30 to 45 feet, Zone 5). Nineteen diseases and eleven pests documented.
Quick Facts
Primary Spore Release
Spring Spore Germination and Infection
Spore Release (Fall & Spring Rains)
Primary Spore Release
+ 10 more — see full disease and pest lists below
Field Observations
Phenological Calendar
As of May 13, 2026, Puget Sound stations range from 1906.2 to 2098.2 GDD₃₂. Red Maple has passed 'leaf emergence' (1364 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 13, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,098 | 'Leaf emergence' | — | — |
| Kent / Auburn | 2,089 | 'Leaf emergence' | — | — |
| Seattle / UW | 2,063 | 'Leaf emergence' | — | — |
| Olympia / Tumwater | 2,025 | 'Leaf emergence' | — | — |
| Tacoma / Puyallup | 1,993 | 'Leaf emergence' | — | — |
| Bellingham / Whatcom | 1,972 | 'Leaf emergence' | — | — |
| Sequim / Rain Shadow | 1,906 | 'Leaf emergence' | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| 'Flower buds visible' BBCH '51' | 1221 | '' |
| 'Fall color / leaf senescence' BBCH '93' | 1228 | '' |
| 'Bud break' BBCH '07' | 1242 | '' |
| ● 'Leaf emergence' BBCH '11' NOW | 1364 | '' |
Source: 'NPN citizen science observations (WA+OR), n=10, median. services.usanpn.org' About GDD₃₂ →
Season tracker for Kent / Auburn as of May 13, 2026. Predicted dates use 16-day weather forecast through May 29, 2026, then climate normals.
Diseases: Regionally Documented (17)
Pests: Regionally Documented (13)
Cultivars (5)
Red maple is not native to our region but it performs well here in zones 2a through 8b. It is one of the first trees to bloom in spring (March-April, as low as 28 GDD base 50) with red flowers before leaves, making it a useful phenological indicator. The tree tolerates wet soil and urban conditions better than most maples, which makes it viable for the poorly drained lowland sites where Japanese maple would struggle. Fall color is variable from seed-grown trees; select named cultivars like 'October Glory' or 'Red Sunset' for reliable color. The standard maple diseases (tar spot, powdery mildew, anthracnose) apply but are cosmetic. Cottony maple scale can be heavy some years. Red maple establishes well in rain gardens and low spots that other trees reject.
— Chris Welch, ISA Certified Arborist