A stunning variety of evergreen with silvery-blue needles, the Colorado blue spruce (Picea pungens var. glauca) can grow to over 100 feet and spread 30 feet wide. It grows in a pyramidal shape with inch-long needles and light brown cylindrical cones. It prefers moist soil and full sun, and is hardy in zones 3 to 7.
Planting Your Spruce Tree
With a shovel, dig a hole at least three times the diameter of the tree's root ball, and as deep as the container or root ball.
Loosen the soil around and in the hole and add peat moss to the soil, in a mixture of 1 part peat moss to 2 parts soil. This will aerate the soil and keep in moisture.
If you have a tree wrapped in burlap, set it in the hole. Cover about two-thirds of the burlap with soil, tamping it down as you fill the hole. Remove the string from around the burlap, open it up and spread it out. It will rot on its own. Continue to fill with soil, up to the dirt mark on the trunk of the three.
Water generously and let the water soak in. Create a moat around the hole with a 2-inch rim and add more water. Let it soak in.
For trees in containers, take the same same steps except that you remove the container by cutting it away. With your fingers or fork, spread out the roots gently to separate them in case they've become too compacted.
Choose the correct location to plant your Colorado Blue Spruce. The trees prefer full sunlight and rich soil. Keep in mind the size of a mature tree and plant well away from building foundations, driveways, sidewalks and overhead power lines.
Water Colorado Blue Spruce at least once a week in hot, dry weather, especially while the tree is young. While mature Blue Spruce will tolerate some drought, the trees prefer moist soil. Water thoroughly allowing water to soak into the soil around the tree. Colorado Blue Spruce have deep roots, so you must provide enough water to soak in to reach the roots.
Mulch the tree with wood chips, pine straw or bark mulch to keep the soil from drying out too much. Spread the mulch out at least 4 feet from the trunk of the tree in all directions, 2 to 3 inches thick.
Prune dead spruce branches in the spring. Spruce can be susceptible to several pests including Cytosporo canker and spruce gall aphids. If you see any sign of disease or insect infestation, cut off the infected branch and consult an arborist about further treatment.
The typical blue spruce in the wild grows to heights of between 80 and 100 feet, with a trunk that may be as thick as 2 feet. The needles can be 1 to 1.5 inches long and stick out from the branches in all directions.
The needles of a blue spruce have four sides; a cross-section view of one would reveal a diamond shape. The needles are bluish-gray to silver-blue, a feature which gives the tree its name.
The native range of the blue spruce is from eastern Idaho into western parts of Wyoming, and south into the middle of Colorado and Utah. New Mexico and Arizona are the southernmost part of its distribution and the tree typically grows at elevations between 6,000 and 11,000 feet.
Blue spruces mature slowly, but the tree is an extremely long-lived species, with some existing as long as 800 years.
Since blue spruce grows in wilderness areas, for the most part, its value as a timber tree is low. Wood from the tree serves as firewood and makes good poles and posts. The color of a blue spruce along with its shape when young makes it an ideal tree for Christmas.
Inspect the needles of a blue spruce tree for signs of disease. Needle cast disease is characterized by a discoloration of the needles, followed by premature needle dropping. Cytospora canker symptoms include a browning of affected branches, as well as a sticky white sap-like residue.
Prune back blue spruce to remove diseased branches. Cut 4 to 6 inches below the areas of visible disease, including brown needles and bare branches. Clean the pruning shears with rubbing alcohol before and after pruning to prevent spread of the fungus.
Bag pruned branches and fallen needles and discard with your yard waste. The fungus may have an opportunity to spread if bags are not sealed appropriately.
Give your ailing blue spruce tree room to grow, recover and breathe. Remove leaves and other debris, both organic and synthetic, from under the tree. Avoid planting other bushes, flowers and plants too close to the tree.
Apply a lime- and copper sulfate-based fungicide to spruces suffering from needle cast. Spray the tree when the needles are half-grown and then again once the needles have reached maturity. You may need to apply chemicals every few weeks for up to two years to completely protect your tree from the disease.
Measure the height of your Colorado blue spruce tree. You need this measurement to determine how much fertilizer to use.
Multiply the height of the spruce tree by 1/3 lb. For example, if your spruce tree was 12 feet tall, you would need 4 lbs. of fertilizer. A spruce tree that measured only 9 feet in height would require 3 lbs. of fertilizer.
Dig several 15 inch holes around the base of your Colorado blue spruce. Make sure none of these holes touch the tree's roots.
Pour the fertilizer in the holes evenly, and cover the holes back up with the soil you removed.
Water the area until the soil is moist but don't over water. Spruce trees can withstand a drought but not a flooding.