Western White Pine

Pinus monticola (Pinaceae) is a large five-needled pine native to the mountains of western North America from British Columbia to California and east to Montana and Idaho. It reaches 100 feet tall with a narrow, symmetrical pyramidal crown and smooth, thin bark that becomes furrowed into small, squarish blocks with age. The soft, blue-green needles are held in bundles of five.

Western white pine grows in full sun on moist, well-drained soils at moderate to high elevations. It was historically the most commercially valuable timber pine in the inland Northwest. White pine blister rust (Cronartium ribicola) has devastated populations throughout its native range since the early 1900s. Breeding programs have produced rust-resistant selections. Hardy in Zones 3a to 8b.

Western white pine has been devastated by white pine blister rust across its native range. The fungus requires an alternate host in the Ribes genus (currants and gooseberries) to complete its lifecycle, which means planting western white pine near ribes species is a recipe for infection. In the Puget Sound lowlands, where both native ribes and cultivated currants are common, this is a serious constraint. Rust-resistant selections exist but are not widely available in the retail nursery trade. The species prefers well-drained, acidic soil and does not perform well in the poorly drained lowland soils typical of the I-5 corridor. It is a high-elevation native and the lowland heat and humidity are not its preference. For most residential landscapes in the I-5 corridor, western white pine is a poor choice unless you have sandy, well-drained soil and no ribes within a few hundred meters.

— Chris Welch, ISA Certified Arborist