Sitka Spruce

Picea sitchensis (Pinaceae) is the tallest spruce species in the world, reaching 180 feet or more in old-growth stands. It is native to a narrow coastal strip from Alaska to northern California, typically within the fog belt. The stiff, sharp needles are flattened with bright silvery-white bands beneath. Bark is thin, scaly, and purplish-gray.

Sitka spruce requires high atmospheric moisture and cool summers, growing naturally where annual rainfall exceeds 60 inches. It is intolerant of drought, heat, and interior continental climates. The wood is prized for musical instruments (particularly guitar soundboards) and was historically critical for aircraft construction. The species is widely planted as a timber tree in the British Isles and northern Europe. Hardy in Zones 6a to 8b.

Sitka spruce is a coastal species and that is the key to growing it in the Puget Sound lowlands. It needs the marine influence: humidity, moderate temperatures, and consistent moisture. Inland from the immediate coast, summer heat stress and dry air open the door to spruce aphid and spider mite, both of which flare in warm, dry conditions. The tree is massive (180 feet in its native range) and fast-growing (40 feet at 20 years), so residential lots are rarely appropriate. In the right site, near-coastal with deep moist soil, it is magnificent. Needle cast diseases are present but manageable. White pine weevil damages leaders but trees usually recover with a replacement leader. For most lowland Puget Sound yards, this tree is too big and too moisture-demanding; reserve it for large properties with coastal exposure.

— Chris Welch, ISA Certified Arborist