Colorado blue spruce can be fertilized when first planted or in early spring before the growth season, according to Garden Guides. Slow-release fertilizer should be sprinkled around the base of the tree, leaving a margin of 8 inches between the fertilized area and the trunk. Use a rake to work the fertilizer into the soil, and then water the area to ensure that the fertilizer seeps down into the roots.
Blue spruce trees thrive in bright sunlight or partial shade and need moist but well-drained soil, according to SFGate. Mulch helps keep the roots moist and keeps pests away. Spruce are susceptible to spider mites and pine needle weevils. While spider mites are microscopic, their presence can be detected by the silky webs on foliage. An infestation of spider mites results in discoloration and defoliation. Pine needle weevils are brown and approximately 1/4 inch long. The larvae eat roots, while adult weevils consume foliage, but they don't kill the infected tree. A blue spruce tree can live up to 800 years. Its maximum height is 75 feet with a 20-foot canopy. With their triangular shape and stiff, blue needles, blue spruce are often used as Christmas trees and ornamental wind barriers.