Trees of Washington and Oregon yards

The tree pages

• Douglas fir: 80–200 feet at maturity, a root plate on clay, failure by saturated-soil windthrow and root rot, Swiss needle cast on the coast, crane removals, and the 20- and 24-inch permit thresholds that catch mature firs.
• Western redcedar: 50–70 feet in a yard, windfirm on dry ground and often blown over on wet ground (USFS), never topped, and “the cornerstone of northwest coast Indian culture” (USDA NRCS).
• Western redcedar dieback: dead tops tied by WSU’s 2023 tree-ring study to hotter, drier summers; 45,630 acres of crown dieback mapped in Washington in 2024; what water and mulch can do, and when a dead top over a roof is a removal.
• Bigleaf maple: fast, wide and multi-stemmed, with included bark at the forks; nearly 25 percent of sampled Washington maples showed decline in the UW and DNR study; shallow roots, pruning timing, and the sprouting stump.
• Laminated root rot: the root disease that windthrows green Douglas fir, spreads root to root, survives for decades in stumps, and makes stump removal the condition for replanting conifers.
• Oregon white oak: 50–90 feet, deep-rooted and very windfirm (USFS); regulated from any size in Oak Harbor and from 3 to 20 inches in Forest Grove, Lakewood, West Linn and Salem; Mediterranean oak borer in six Oregon counties.
• Ponderosa pine: the long-needled pine of Spokane, Yakima, Bend and Klamath Falls; wet-snow breakage, bark beetles after drought, the October-to-February removal window and the permit rules in pine country.
• Red alder: matures at 60–70 years and rarely passes 100 (USFS); heart rot in older trees; and the Puget Sound cities that leave alder out of their significant-tree counts.
• Oregon ash: the only native Northwest ash, a wetland and streamside tree that ODF expects emerald ash borer to hit hard; identification, treat-or-remove, and Oregon’s ash-wood quarantine.

How to use these pages

A thinning crown has a different cause in each species: drought in a cedar, needle cast in a coastal fir, root rot in a fir on former timberland, heat near roads in a maple. The pages separate watering problems from structural ones, and all end at the same door: a certified arborist’s tree risk assessment, then tree trimming or tree removal, with modeled ranges on tree removal cost.

Permit thresholds matter because these species get big: Portland regulates private trees from 12 inches DBH and adds public notice at 20 inches (PCC 11.40); Seattle’s Tier 2 starts at 24 inches (SMC 25.11); Renton sets 30 inches for bigleaf maple (RMC 4-11-200). City tables are in Oregon tree removal permits and Washington tree removal permits; ash and oak quarantine pests are under pests.

Related guides

• Types of maple trees in WA and OR
• Pine vs fir vs spruce: a field key to Northwest conifers
• Aspen vs birch: telling the white-barked trees apart
• Washington and Oregon state trees
• Washington and Oregon hardiness zones by ZIP
• Best time to plant trees in the Pacific Northwest

Tree guides

Questions homeowners ask about their own trees: how old is my tree, moss and lichen on trees and oak galls. More in the guides.