Picea glauca Seeds | White Spruce
LATIN NAME: Picea glauca
COMMON NAME: White Spruce
Plant Profile
White spruce is the conifer of the northern limit, a tree of fifteen to twenty-five metres with short blue-green needles and cones that ripen in a single season and fall whole. It grows from Alaska across Canada to Newfoundland, and it is the species that finally gives out at the tree line in the Mackenzie and in Labrador.
In the open it keeps its branches to the ground and forms a narrow spire, which is why it is cut for Christmas trees in the millions. In the forest it self-prunes into a straight, fine-grained log, and that log is the backbone of the Canadian pulp industry. The bark is thin and grey, and it stays smooth for most of the tree’s life, which is one reason a spruce stand is easily damaged by fire.
Science & Biotechnology
The northern limit of the species is not set by cold alone. Seedlings need a summer long enough to harden before frost, and at the tree line the limit tracks the position of the arctic front rather than latitude, which is why the line runs further north in the interior than on the coast.
White spruce hybridises freely with black spruce where the two meet, and the hybrids are hard to tell apart without cone scales. The species was among the first conifers to have its genome sequenced, largely because of its economic weight, and the sequence showed a very large genome with a high proportion of repeated elements, a pattern shared with other pines.
Uses & Benefits
The wood is light, straight-grained and almost colourless, which suits it to framing timber, to newsprint and to musical instrument soundboards. In Canada it is sold with fir and pine under the SPF grade, and the three are rarely separated at the mill.
Roots split into long flexible withes were used to sew birchbark canoes across the boreal zone, a use that survived into the twentieth century. The inner bark was boiled for a spring tonic, and the needles were brewed for a drink high in vitamin C, though the taste is resinous and bitter.
Growing from Seed
Seed needs three weeks of cold moisture before it will germinate, and it germinates best on a bare mineral surface in full light rather than in shade. Surface sow, press the seed into the mix and do not cover it deeply, since light helps.
The first three years are slow, and a seedling may be fifteen centimetres tall after two seasons while it builds a root system. Plant out at three or four years, when the tree is thirty centimetres, and keep the grass cut around it. Squirrels cut the cones in late summer, so collect seed as soon as the scales begin to separate. Seed collected from trees at the northern edge of the range is worth having, since local provenances harden off earlier in autumn than southern ones.
Our Take
A tough, fast-growing spruce for cold ground and wind, and the best conifer for a shelterbelt in a short season. Give it light and space and it will outlive the house.
Related Reading
Gardeners who grow White Spruce often pair it with these related subjects: