Colorado Blue Spruce

SCIENTIFIC NAME: Picea pungens

FAMILY: Pinaceae

This tree in Colorado: This is Colorado's state tree. It is normally found growing along streams from 6,000 to 9,000 feet elevation. In communities with a similar elevation the tree will perform admirably.

Hardiness: Zones 3 to 7.

Growth habit: Strongly pyramidal as a young tree with a prominent excurrent growth habit. Maintaining a dominant central leader in a younger tree makes this an attractive tree for many years. This is normally a large tree so give it plenty of room to reach its full potential. Where there is adequate room the lower branches should be allowed to remain on the tree. Height around 60 feet with a spread of 30 feet. It is a shorter tree in hot dry climates (e.g., Grand Junction, CO).

Foliage: Single pointy needles encircle the stem. Usually grow at right angles to the stem. Needles are stiff and prickly when grabbed, which gives this tree a unique identifying characteristic. Needles have a acid taste when chewed.

Flowers: Both mail and female flowers are found on the tree.

Fruit: A cone 2 to 4 inches long. Green in color when immature. Yellow-brown after seeds have emerged.

Bark: Only visible when lower limbs have been removed. Furrowed and gray in color.

Insects and diseases: Cooley spruce gall aphid (i.e., adelgid) causes cone-like growth on branch terminal buds. This pest is more of a nuisance than a problem. Other pests include spider mites and Cytospora fungus.

Cultivars: There are several Colorado spruce selections available mostly because of their blue needle color. The most popular cultivar seems to be Fat Albert. Other cultivars include Hoops, Koster, and Iseli fastigiate (narrow upright habit).

Landscape value: Needle color can be green, blue, or silver blue. The fact that some trees are green in color prompted the name change to Colorado spruce. Like aspen trees this tree is extremely popular in Colorado landscapes. Trees are attractive as singles or in groups. They can be used as an accent tree or as a screen. Because this is a large tree adequate space for the tree to grow in to must be strongly considered before planting. The cultivar requires a large open space in order to develop fully, and so is not recommended for small home grounds.

Interesting features: The blue spruce is the state tree for both Colorado and Utah. The current national champion is located on the Ashley National Forest north of Duchesne, UT. This champion is 127 feet tall. The circumference measured at 4.5 feet above the ground is 190 inches (5 feet). The crown spread is 43 feet.

Information sources: Michael Dirr, Manual of Woody Landscape Plants (University of Georgia, 1990) USDA Forest Service, Silvics of North America, Volume 1 -- Conifers

Photo by: Gardening Know How