Introduction to Colorado Blue Spruce:
Colorado Blue Spruce has a horizontal branching habit and grows taller than 75 feet in its native habitat but is normally seen at 30 to 50 feet in landscapes. The tree grows about twelve inches per year once established but may grow slower for several years following transplanting. Needles emerge as a soft clump, changing to a stiff, pointed needle sharp to the touch. The crown form varies from columnar to pyramidal, ranging from 10 to 20 feet in diameter.
Blue Spruce Specifics:
Scientific name: Picea pungens
Pronunciation: PIE-see-uh PUN-jenz
Common name(s): Colorado Spruce, Colorado Blue Spruce, Blue Spruce
USDA hardiness zones: 4 through 7
Origin: native to North America
Uses: screen; specimen; Christmas tree; no proven urban landscape tolerance
Availability: generally available in many areas within its hardiness range
Colorado Blue Spruce Silviculture:
Light requirement: tree grows in part shade/part sun; tree grows in full sun
Soil tolerances: clay; loam; sand; acidic; occasionally wet; alkaline; well-drained Drought tolerance: moderate
Aerosol salt tolerance: high
Soil salt tolerance: moderate
Colorado Blue Spruce Description:
Height: 30 to 50 feet
Spread: 10 to 20 feet
Crown uniformity: symmetrical canopy with a regular (or smooth) outline, and individuals have more or less identical crown forms
Crown shape: columnar; pyramidal
Crown density: dense
Growth rate: slow
A number of cultivars are listed. The most common cultivar is ‘Glauca’, the Blue Colorado Spruce. The blue trees are sometimes grown from seeds, so they vary in degree of blue coloration. For reliable blue color, purchase a grafted, named cultivar selected for its blue color.
Some cultivars: ‘Argentea’; ‘Glauca’; ‘Glauca Procumbens’; ‘Globosa’; ‘Hoopsii’; ‘Moerhiemii’; ‘Pendens’;‘Thompsoni’.
Colorado Blue Spruce casts dense shade when branched to the ground, so no grass grows beneath it. Colorado Blue Spruce lends a formal effect to any landscape due to the stiff, horizontal branches, and blue foliage. It is often used as a specimen or as a screen planted 10 to 15 feet apart.
The tree prefers a rich, moist soil, and benefits from irrigation in dry weather. Trees benefit from a layer of mulch extending beyond the edge of the branches. This keeps roots cool and reduces moisture loss from the soil.
Blue spruce grows in full sun or in shade on the north side of a building. The conifer tolerates clay soils. Susceptibility to canker makes this tree a questionable choice for large-scale planting in the eastern states. Substitute White Fir (Abies concolor) for the same blue foliage effect without the disease problem. Also, the wax coating on the needles which gives the blue color can be washed off by some pesticides. Check the label and test the spray on a small scale before spraying.