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Blue spruce, or Picea pungens, is an evergreen tree native to western North America. The plant is also referred to as Colorado Spruce and is found in certain parts of the Rocky Mountain range. It's physically characterized by a dense crown and sharp needles. This tall tree grows slowly, especially during its first years. It makes a good shade tree so long as it is located in a cool climate and given partial to full sun, well-drained soil, and irrigation as well as mulch.
This specimen is primarily found in the central and southern Rocky Mountains located in the Western United States. The area includes parts of Wyoming, Idaho, and Utah as well as Arizona, New Mexico, and Colorado. Populations of the tree thrive near streams and mountain valleys.
The tree is a tall, upright evergreen. Its large, dense crown spreads in a columnar or pyramid shape, measuring between 10 and 20 feet (approximately 3 to 6 meters) across. The extremely sharp needles range in color from grayish to blue, and its fruit cones are long, cylindrical, and chestnut brown with paper scale-like seeds.
The blue spruce grows slowly during establishment, but, after the first few years, it gains about 12 inches (31 cm) annually. The average spruce grows to an adult height of between 30 and 50 feet (about 9 and 15 meters). A tree located in its native habitat, however, may reach well above 75 feet (about 23 meters).
This tree works well for use as a shade tree or privacy screen because of its dense crown. Grass will not grow beneath it, so it needs a clear area in which to grow, preferably level with surrounding land or on a slope above it. The blue spruce needs cooler temperatures to thrive, ideally averaging between 39° and 43° Fahrenheit (about 3.9° to 6.1° Celsius).
Light requirements for blue spruce are flexible, as it does well in full or partial sun. It has moderate drought tolerance, but thrives in moist, well-drained soil. The tree also adapts to clay, sandy, or alkaline earth and loam with high salt content. Irrigation and mulching may benefit the plant for moisture balance.
There are some concerns for the growth of the blue spruce. It is susceptible to some pests and diseases, including the needle miner, which bores into a leaf and removes the center, and aphids and mites may also pose a problem. Rust diseases and needle casts can infect the plant, causing leaves to yellow and drop.
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