Colorado spruce is native to the Rocky Mountain region of the United States. It is a very common variety of spruce and is often called a Colorado blue spruce. This tree can live between 50 and 100 years and can grow to 80 feet tall and 20 feet wide, so consider your planting location carefully. Colorado spruce will tolerate a range of soils ranging from clay, clay loam, loam and sandy soils. You might want to augment a heavy clay soil to help encourage a healthy young tree. Established trees should be able to grow well in heavy clay soils.
In the spring after the risk of frost has passed, dig a hole slightly larger than the root ball of the tree you are planting. This will be your base hole.
Continue removing about half again as much soil from the existing hole. Put this soil in a separate pile.
Augment your clay soil with 10 percent to 15 percent sand and about 10 percent to 15 percent leaves or other organic material. If the clay is unusually dense, increase the percentages.
Mix the soil thoroughly using a shovel. A hoe or rake can be handy to break up clay clumps.
Backfill with your new soil mix until you can place the tree so that the top of the root ball is a couple of inches below the level of the adjacent land.
Fill in the hole. Make sure that the tree is held firmly by the soil. Keep some of the soil to compensate for settling over the first few months.