Colorado Blue Spruce (Picea pungens)
Because of their sharp, prickly needles, Colorado Blue Spruces are more resistant than many other landscape plants to deer damage in many areas. Although they are tough and grow in any type of soil, they are intolerant of air pollution and very wet soil.
Blue Spruces grow 30 to 40 feet in landscape situations, much shorter than their natural height in the wild, and may reach 350 years of age. They are slow growers, adding 5 or 6 feet every 10 years. Fairly narrow in habit, they maintain a spread of roughly ¼ of their height, and possess the distinctive “Christmas tree” shape. Their rigidly horizontal limbs turn up slightly at the tips, especially when they are young. Some varieties spread more widely or have weeping branches, and there are dwarf types that grow only 2 or 3 feet tall. The bark is thin becoming moderately thick with age. It is somewhat pale gray in small flattened scales when young, then turns reddish brown and furrowed with age. Blue Spruce is moderately shade tolerant and grows best in deep, rich, gravely soils, often along stream banks and other sites with high moisture levels. A deep penetrating root system makes the species resistant to being blown over.
The evergreen needles are stiff and stout, about 3/4 to 1¼ inches long, and sharply pointed. Unlike the flat needles of other conifers, spruce needles are four-sided and roll easily between your fingers. They spiral around the twigs and branches at right angles in all directions. Bluish-green, tending toward silver, their color varies widely from tree to tree. This silvery-blue cast is from a powdery patina produced by the tree. For this reason it is most prominent in the spring on new growth and less obvious in the winter when winds dissipate much of the coating. Needles growing in the interior of the tree near the trunk tend to be more green than blue all year. They last for 4 to 6 years. New needles may be silvery-gray with a white cast to them.
As conifers, Blue Spruces bear cones, which are actually male and female flowers borne separately in clusters on the same tree. Male cones are orange colored, soft, and appear on the lower branches, while female cones are greenish to red-purple and appear on upper branches. They appear on older trees in late May or early June. As the season progresses the male cones fall off and the female cones dry out and turn tan. From 2½ to 4 inches long, they hang downward, lasting from July through to January.
Blue Spruce Choices
Some superior versions of Colorado Blue Spruce include Fat Albert which grows to 10 to 15 feet tall and nearly as wide and has rich blue needles. Foxtail is narrow and upright growing to 10 to 15 feet tall with twisted needles that tuft at branch tips. Glauca Pendula has a sprawling, drooping form. Globosa is a dwarf type that is flat topped, dense, and grows to 3 feet. Hoopsii has silver-green needles and grows relatively rapidly. Koster has a conical form with silver-blue needles. Moerheimii is slow growing and narrow in form. Reputed to be the “bluest”. Montgomery is compact and shrub-like with silvery-blue needles. Thompsenii has a thick, intense whitish-silver cast on blue needles.