Washington State Native Plants for the Home Garden
Washington state is divided into two distinct climatic regions by the Cascade Range. West of the Cascades (zones 7b–9b) is the maritime Pacific Northwest: mild, wet winters; cool, dry summers; acidic soils derived from glacial till and volcanic material. East of the Cascades (zones 4a–7a) is.
Washington state is divided into two distinct climatic regions by the Cascade Range. West of the Cascades (zones 7b–9b) is the maritime Pacific Northwest: mild, wet winters; cool, dry summers; acidic soils derived from glacial till and volcanic material. East of the Cascades (zones 4a–7a) is semi-arid to arid: cold winters, hot dry summers, alkaline soils derived from basalt.
These are not two versions of the same climate — they are fundamentally different growing environments requiring different native plants.
Per Washington State University Extension, native plants for western Washington are often not suitable for eastern Washington, and vice versa. Gardeners need to select species native to their side of the Cascades.
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Western Washington Native Trees (Zones 7b–9b)
Pseudotsuga menziesii (Douglas Fir)
Zones 4–8 | Full sun | Mature: 80–200 feet (forests); 40–60 feet in gardens in 50 years
Per Oregon State Extension, Douglas fir is the dominant timber tree of the Pacific Northwest and an ecologically critical species. It is too large for most residential lots at maturity but grows slowly enough in gardens that it provides shade and wildlife habitat for decades before becoming a maintenance concern. Massive wildlife value — cones feed crossbills and Douglas squirrels; the tree supports dozens of caterpillar species.
Acer macrophyllum (Bigleaf Maple)
Zones 6–9 | Full sun to part shade | Mature: 30–75 feet
Per Oregon State Extension, bigleaf maple is native throughout western Washington in moist woodland sites. The very large leaves (8–12 inches across) are distinctive. Outstanding fall color. Moss and ferns colonize the bark naturally in the Pacific Northwest's moist climate. Tolerates part shade and moist soils.
Alnus rubra (Red Alder)
Zones 5–8 | Full sun | Mature: 40–60 feet
Per Washington State University Extension, red alder is the most common native deciduous tree in lowland western Washington, native to moist sites near streams and disturbed areas. It is a nitrogen fixer. It grows rapidly (2–4 feet per year) but is short-lived (50–70 years). Excellent for quickly establishing a native planting.
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