Spruces (Picea spp.) are evergreen trees and shrubs from the pine family and come in a wide range of sizes, including dwarf cultivars. Blue spruce or Colorado blue spruce is a tree variety from the group. Spruce trees are well-adapted to nearly all climatic zones depending on cultivar and most of them produce cones. The dwarf spruce varieties are best adapted to cooler regions.
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The blue spruce tree (Picea pungens "Glauca") is also commonly known as the Colorado blue spruce and silver spruce. The tree is a native of the Rocky Mountains in the United States and grows to a mature height of more than 80 feet tall with a trunk diameter of 1 to 2 feet. The tree canopy measures about 30 feet at maturity.
The blue spruce tree gets its name from its blue-green to silvery blue color. The four sided, pointed needles are 3/4 to 1 1/4 inches long and 1/16 inch wide. The cones are composed of papery scales and range in length from 2 1/2 to 4 inches. The dense textured branches start to grow very low on the trunk covered with ash-brown colored, flaky bark. Blue spruce tree roots are spreading and shallow.
Plant the tree in an area of full sun as the tree is intolerant of shade. Though the blue spruce prefers a moist soil to grow well, the tree has the highest drought tolerance among all the spruces. In its native habitat, the tree grows on stream banks and moist areas at elevations of 6,000 to 11,000 feet. Preferred soil is loam with a pH between 6.0 to 7.5. Do not plant in overly wet ground or in sites that are likely to flood.
Blue spruce is susceptible to damage from a number of pests. These include the spruce seed chalcid (Megastigmus piceae), the larvae of the spruce seed moth (Laspeyresia youngana) and the cone-boring pest called cone cochylid (Henricus fuscodorsana). The needle-eating larvae of the western spruce budworm (Choristoneura occidentalis) often strike trees during late April. Uncontrolled, heavy infestations are likely to kill the tree.