How to Select Trees for Washington Landscapes

Choosing the right tree for a site in Washington State requires more than picking a pretty species. The state spans multiple climates, soils, and exposures: coastal salt spray and high rainfall on the west side; maritime lowland climates around Puget Sound; steep, forested mountain slopes; and dry, continental conditions east of the Cascades. Selecting trees that fit the actual conditions of a planting location reduces failure, cuts long-term maintenance, and improves benefits like shade, wildlife habitat, screening, and storm protection.

Understand Washingtons growing regions and common constraints

Washington is not uniform. Before selecting species, know which macro-region and micro-site you are working with. Consider these generalized regions and the key constraints they impose.

Western Washington (Coast, Olympic Peninsula, Puget Sound)

Western Washington is mild and wet, with acidic soils in many places, seasonal waterlogging in low areas, and frequent wind and salt exposure on coastal bluffs. Root rot pathogens (Phytophthora) can be active in poorly drained soils. Shade-tolerant species do well in riparian and forested settings.

Cascade Range and foothills

Elevation and aspect matter. Cold air drainage, seasonal snow load, and wind-exposed ridgelines require hardy, wind-firm species. Soils are often shallow or rocky on slopes.

Eastern Washington (Columbia Basin, Palouse, interior valleys)

This region is drier, sunnier, and has greater temperature swings. Soils range from deep loams to fine glacial deposits and can contain mineral salts in some irrigated areas. Drought tolerance and tolerance of alkaline soils are often critical.

Site assessment: what to measure before you plant

A thorough site assessment prevents mistakes. Spend 20 to 60 minutes on a small property; for larger sites, map conditions.

Identify microclimate: sun exposure (full sun, part shade, shade), prevailing wind direction, and high-wind corridors.
Record soil type and drainage: sandy, loam, clay; do a simple percolation check by digging a hole, filling it with water, and measuring infiltration over a few hours or a day.
Note existing overhead and underground constraints: power lines, sewer, septic, sidewalks, and driveways.
Measure available root space: distance to building foundations and paved surfaces on all sides. Roots need room to avoid structural damage and to sustain mature canopy.
Consider salt or spray exposure: coastal locations and roads treated with deicing salts require tolerant species.
Check legal and utility restrictions: local ordinances on planting distances and permitted species, and contact utilities for underground service locations.

Choose trees by purpose and maturity size

Define the primary purpose for the tree: shade, screening, windbreak, specimen, fruit production, or ecological restoration. Purpose drives size class and species selection.

Size classes and recommended uses

Small trees (20 feet mature height or less): suitable under power lines, near structures, for courtyard spaces. Examples: serviceberry, Pacific ninebark, Korean Stewartia (in appropriate climates).
Medium trees (20 to 40 feet): common street trees and backyard shade trees. Examples: red alder (western), crabapple (cultivars for cold climates), Japanese maple (sheltered sites).
Large trees (40+ feet): major shade and canopy trees; require large rooting area and distance from utilities. Examples: Douglas-fir, bigleaf maple, ponderosa pine.

Always choose a mature size that fits the available canopy and root space. A common mistake is planting a “small” cultivar that is promoted but outgrows its site in 20 to 30 years.

Consider native versus non-native species

Native species are adapted to local pests, soils, and climate and often provide superior wildlife value. However, non-native species can be appropriate in urban sites when chosen for specific tolerance traits (pollution, compaction, salt).

Favor natives for ecological restoration and riparian plantings: Western red cedar (Thuja plicata), Sitka spruce near coast, bigleaf maple, red alder, ponderosa pine east of the Cascades.
Use non-natives selectively in urban or high-stress sites when they address a specific challenge: honeylocust for sidewalk tolerance, ginkgo for pollution tolerance, or certain cultivars of crabapple for urban fruit production.

Be careful to avoid species known to be invasive in the Pacific Northwest, such as tree-of-heaven (Ailanthus altissima), and avoid planting species banned by local ordinances.

Recommended species by region and function

Below are practical suggestions, with notes on conditions where each performs best. Choose local provenance when buying native species.

Coastal and Puget Sound (wet, mild, salt exposure possible)

Bigleaf maple (Acer macrophyllum): excellent shade tree; prefers moist, well-drained soils; shallow roots–avoid close to foundations.
Western red cedar (Thuja plicata): windfirm, excellent for screens and hedges; tolerates wet soils.
Pacific dogwood (Cornus nuttallii): native understory/specimen; needs protection from wind and late frosts.
Red alder (Alnus rubra): fast-growing nitrogen fixer for restoration sites and quick screening; short-lived relative to conifers.
Pacific madrone (Arbutus menziesii): attractive evergreen broadleaf for well-drained slopes; intolerant of heavy clay or constant moisture.

East of the Cascades (dry, continental)

Ponderosa pine (Pinus ponderosa): drought-tolerant, suitable for open sites and windbreaks.
Rocky Mountain juniper (Juniperus scopulorum): xeric tolerant; good in rocky soils and as specimen.
Serviceberry (Amelanchier alnifolia): small native tree or large shrub, good for fruit and wildlife.
Apple and pear varieties: many apples and pears perform well with irrigation; choose varieties adapted to local chill hours and disease pressure.

Urban/street and small-site recommendations

Crabapple cultivars (disease resistant): small-flowered, ornamental fruit trees for urban yards.
Honeylocust (Gleditsia triacanthos var. inermis): tolerant of compacted soils and root space constraints; filtered shade good for lawns.
Japanese maples (Acer palmatum): small, decorative, best in sheltered, partially shaded sites in the west.

Practical planting and early care steps

Getting the planting right in the first two to three years determines long-term success.

Dig a planting hole no deeper than the root ball and at least twice as wide. Backfill with native soil; do not bury the root flare.
Position the root flare at or slightly above finished grade. Planting too deep is the most common fatal error.
Remove burlap, wire cages, and excessive pot-bound circling roots. Cut circling roots to encourage radial rooting.
Stake only if necessary (unstable or windy sites). Remove stakes after one year to allow trunk movement and strengthening.
Mulch 2 to 4 inches deep, keeping mulch pulled back 2 to 4 inches from the trunk to avoid rot. Avoid “volcano” mulching.
Water deeply and infrequently to encourage deep root growth. Typical schedule for the first two growing seasons: once or twice weekly during the dry season for non-irrigated sites, adjusting for soil type and weather. For established trees, irrigate during prolonged droughts.
Prune only to remove dead, diseased, or crossing branches in the first few years. Prune structural form in young trees to develop a single trunk and balanced scaffold branches.

Pest, disease, and biosecurity considerations

No tree is immune. Plan for pests and diseases appropriate to the species and region.

Emerald ash borer (EAB) threatens Fraxinus species nationwide. Avoid heavy reliance on ash; diversify species palette.
Phytophthora root rots are an issue in poorly drained western soils. On wet sites, favor water-tolerant native species and improve drainage if planting intolerant species.
Needle blights and rusts can affect conifers and ornamentals. Select disease-resistant cultivars when available and maintain good airflow in planting design.
Sudden oak death affects some coastal vegetation; monitor for symptoms and follow local quarantine rules when they apply.

Diversify species and ages to reduce the risk that one pest or disease will remove a large portion of the canopy. Use inspected nursery stock and follow local quarantine and inspection requirements for moving plant material.

Long-term planning and maintenance budgeting

Trees are long-term investments. Plan budgets and maintenance schedules up front to ensure survival and value.

Allocate at least three to five years of watering and monitoring for newly planted trees.
Include routine pruning every 3 to 7 years for young trees to train structure and every 10 years or so for mature trees, depending on species and site.
Budget for replacement planting over decades. A city or private property should expect to replace a minority of trees over time due to age, storm damage, or changing site conditions.

Quick decision checklist for selecting a tree in Washington

What is the planting region (west of the Cascades, Cascades, east of the Cascades)?
What is the sun exposure and wind exposure at the site?
What is the soil texture and drainage condition?
How much root and canopy space is available at maturity?
Is salt tolerance required (coastal or deicing road exposure)?
Are there utilities or ordinances that limit size or species?
Is the goal ecological restoration, shade, fruit, or screening?
Can you obtain local-provenance stock for natives, and is the nursery stock inspected and healthy?

Answering these questions will narrow the candidate list to species that succeed without excessive intervention.

Conclusion: match species to site, not desire to landscape trends

The most successful tree plantings in Washington start with careful site assessment, selection of species adapted to local climate and soils, and realistic planning for space and maintenance. Favor native trees for restoration and habitat projects, diversify species to reduce pest risk, and choose smaller-stature trees for constrained urban sites. With the right match, a planted tree will provide shade, beauty, wildlife habitat, and storm resilience for decades.