Culture Notes
This is a beautiful tree when it can be ground properly without disease. Unfortunately, it is very susceptible to a stem canker that disfigures the tree. If you select this tree in the eastern US, plant only a few to prevent disappointment should disease strike. The tree grows best in rich, moist soil, and will benefit from mulch placed out to the edge of the canopy. Irrigation in dry weather also helps. Best growth occurs in full sun. Trees tolerate clay soil and occasionally wet soil very well. Colorado Spruce casts dense shade when branched to the ground, so no grass grows beneath it. Good survival in ice storms. This is a great plant for a dwarf conifer garden.
Planting and establishing shrubs
The most common cause of young plant failure is planting too deep. Plant the root ball no deeper than it was in the nursery. In most instances, the root flare zone (point where the top-most root in the root ball originates from the trunk) should be located just above the landscape soil surface. Sometimes plants come from the nursery with soil over the root flare. If there is soil over this area, scrape it off. The planting hole should be at least twice the width of the root ball, preferably wider. In all but exceptional circumstances where the soil is very poor, there is no need to incorporate anything into the backfill soil except the loosened soil that came out of the planting hole. Never place ANY soil over the root ball. If a row or grouping of plants is to be installed, excavating or loosening the soil in the entire bed and incorporating organic matter enhances root growth and establishmen
t rate.
Weed suppression during establishment is essential. Apply a 3-inch thick layer of mulch around the plant to help control weed growth. Keep it at least 10 inches from the trunk. If you apply it over the root ball, apply only a one or two inch layer.  This allows rainwater and air to easily enter the root ball and keeps the trunk dry. Placing mulch against the trunk or applying too thick a layer above the root ball can kill the plant by oxygen starvation, death of bark, stem and root diseases, prevention of hardening off for winter, vole and other rodent damage to the trunk, keeping soil too wet, or repelling water. Regular irrigation through the first growing season after planting encourages rapid root growth, which is essential for quick plant establishment.Â
Pests, Diseases and Damaging Agents
Pests: Mites are the worst pest problem. Two gall-forming insects commonly attack Spruce. Eastern Spruce gall adelgid forms pineapple like galls at the base of twigs. Galls caused by Cooley's Spruce gall adelgid look like miniature cones at the branch tips. Bagworms make a sack by webbing needles and debris together. In northern climates, Spruce budworm larvae feed on developing buds and young needles. The Spruce needle miner makes a small hole in the base of a needle then mines out the center. Pine needle scale is a white, elongated scale found feeding on the needles only. Sawfly larvae may feed on the needles. Borers can infest trees which are weakened by other problems.
Diseases: Cytospora canker infects branches and trunks then eventually kills it. The disease can be severe. Spruce may be attacked by needle casts. Several rust diseases attack Spruce but these are rarely seen.
This genus is sensitive to fluoride air pollution, sources of which include glass and brick manufacturing plants and other facilities that heat or treat with acid materials containing fluoride. Symptoms due to fluoride injury are more prominent on the side of the plant facing the pollution source. In deciduous plants, symptoms include leaf browning along the margins of the leaves. A dark brownish band may appear along the boundary between healthy green tissue and the affected brown tissue. Eventually, the entire leaf may turn brown. In conifers, the tips of the current year's needles turn reddish brown. Older needles are typically unaffected. If you suspect fluoride has injured this plant, look in the neighborhood for gladiolus plants. They serve as indicator plants for fluoride air pollution damage because they are very sensitive to it. Other sensitive plants include ash, maple, oak, white pine, poplar, and redbud. Plants that resist injury include birch, flowering cherry, dogwood, hawthorn, American linden, juniper, pear, spirea and sweet gum.
This genus is sensitive to sulfur dioxide air pollution. Sources of sulfur dioxide air pollution include fossil fuel combustion, smelting and refining of ores. Damage usually is confined to urban areas near power stations. Acute injury typically occurs when plants are exposed to high concentrations for a short period. In deciduous plants, tissue between veins on the upper and lower side of the leaf turns yellow, white or tan-brown. The veins usually remain green. In conifers, the tips of needles turn reddish-brown. As damage accrues, the discoloration progresses toward the base of the needle. Deciduous plants exposed to low concentrations of sulfur dioxide for long periods of time (chronic exposure) show a general chlorosis or yellowing of the foliage. Needles on conifers exposed to chronic sulfur dioxide turn yellow and drop from the tree prematurely. If you suspect sulfur dioxide has injured this plant, look in the neighborhood for blackberry, raspberry, pumpkin, or squash plants. These serve as indicator plants for sulfur dioxide air pollution damage because they are very sensitive to it. Other sensitive plants include apple, birch, white pine, poplar, blue spruce and zinnia. Plants that resist injury include box-elder, dogwood, black gum, juniper, maple, spruce and sycamore.