Colorado blue spruce (Picea pungens) makes a lovely addition to a landscape. These large evergreens are native to Colorado and other western mountain states. Spacing will depend on where you are planting them and for what purpose.
You need plenty of space to grow Colorado blue spruce as a specimen tree. They may grow to 115 tall, according to the Colorado State Forest Service. With a crown width of 15 to 25 feet, North Dakota State University horticulturalists recommend planting them 15 to 20 apart.
In their native habitat, Colorado blue spruces grow in dense stands. This trait makes them well suited for windbreaks. PennState Cooperative Extension specialists note that a single row of spruces planted 6 feet apart will provide a windbreak. If you have the space, three or four rows of trees planted 8 feet apart with 10 to 12 feet between rows works even better.
Some growers plant Colorado blue spruce for Christmas trees. Michigan State University foresters recommend planting trees for Christmas tree harvest 6 feet apart.
Disease concerns also affect tree spacing. University of Wisconsin-Madison plant pathologist Brian Hudelson advises that to avoid Cytospora canker, a common fungal disease of Colorado blue spruce, space newly planted trees far enough apart to allow good air flow, or prune established trees so they have open canopies.