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Picea glauca

white spruce

Pinaceae Northern North America (boreal)

Deer Resistant Fragrant (moderate)

Native to North America

SunFull Sun

WaterMedium

HardinessZones 2–6

Overview

Picea glauca is an evergreen coniferous tree 50-100 feet (15-30 m) tall with a dense, conical to spire-like crown and a straight trunk. The four-sided needles are 0.4-0.75 inch (10-19 mm) long, blue-green to dark green with a waxy bloom, set spirally and densely on hairless twigs, and release a sharp, musky odour when crushed that gives rise to the name cat spruce. The bark is thin, grey-brown, and flaky. Slender, hanging cones 1-2.5 inches (2.5-6 cm) long ripen from green to pale tan in autumn, with thin, flexible, smooth-edged scales, and fall whole after shedding seed. P. glauca is among the chief trees of the North American boreal forest, growing across the continent from Alaska to Newfoundland on a wide range of soils. It is slow to moderate in growth and very cold-hardy, but struggles with heat, drought, air pollution, and spider mites in warm regions. The shallow roots make tall trees prone to windthrow on exposed sites.

Native Range

Picea glauca is native across northern North America, forming a transcontinental band of boreal forest from Alaska and the Yukon east to Labrador and Newfoundland, and south into the northern United States. It grows on glacial soils, riverbanks, and rocky uplands throughout the boreal zone.

Suggested Uses

Planted as a windbreak, screen, and specimen tree in cold-climate gardens, parks, and shelterbelts. It is grown for timber, pulpwood, and as a cut Christmas tree across the north. The dense evergreen form suits large, open, naturalistic landscapes.

How to Identify

White spruce is known by its four-sided blue-green needles that roll easily between the fingers and give off a musky, skunk-like smell when crushed. The twigs are hairless, and the slender hanging cones have thin, flexible, smooth-margined scales. P. glauca differs from Picea mariana, black spruce, which has shorter needles, hairy twigs, and small rounded cones, and from Picea abies, Norway spruce, whose cones are far longer.

Appearance

Size & Dimensions

Height50' - 100'

Width/Spread10' - 20'

Reaches mature size in approximately 40 years

Colors

Foliage Colors

green

blue

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~2 weeks

Spring

As a conifer it bears cones rather than flowers. Pollen is shed from small male cones in spring, usually May, while young reddish female cones stand upright before bending down to mature. Seed cones ripen by late summer and drop over autumn and winter.

Detailed Descriptions

Foliage Description

blue-green to dark green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.0 - 7.5(Neutral)

357912

Soil Types

loam sand clay

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

30-40 years

Care & Maintenance

Care Guide

Grow Picea glauca in full sun on moist, well-drained, slightly acidic to neutral soil, though it adapts to sand, loam, and clay. It is very hardy, through USDA zones 2 to 6, and withstands cold, wind, and poor northern soils. The species declines in heat and humidity south of its range, where spider mites, needle cast, and drought stress build up. Water during dry spells in the first few years and while young trees establish. A mulch over the shallow roots keeps them cool and moist. It needs little feeding on reasonable ground.

Pruning

Prune in late winter or early spring to take out dead, damaged, or competing leaders while keeping the natural conical form. Spruces tolerate light shaping but do not resprout from old bare wood, so cuts stay within green growth. Little routine pruning is needed beyond deadwood removal.