Those quaking aspens you admire so much in the Rocky Mountains can be grown in yards if given a lot of care and patience. Nursery-purchased aspens usually have been moved from native mountain soils, often with little of the rootball intact. They prefer well-drained, acid soil and are prone to disease and pests in yards. Even with the best care, they usually live only 25 to 30 years, according to the Colorado State University Extension Office.
Plant aspens in early spring before new growth emerges. Make sure the planting soil slants away from the trunk of the tree to ensure drainage. Dig a hole twice as wide and as deep as the aspen's rootball. Set the dirt aside on a tarp for easier handling. Mix 2 quarts sand and 7 quarts compost with the potting soil and build a berm from the soil 24 inches high and 3 feet wide, if you have heavy clay soil. Dig a hole in the berm for your aspen.
Remove the aspen tree from its container. Cut away any metal wires, plastic or burlap that surround the rootball. Hold the tree at the base of the trunk. Place it level in the hole or slightly above the surrounding soil.
Mix the soil on the tarp with two shovelfuls of compost. Backfill the hole three-fourths of the way with the soil. Fill the hole with water and allow it to drain. Top off the hole with the remaining soil and tamp down gently with your foot to remove air pockets, being careful not to compact the soil.
Build a wall of soil 3 inches high around the aspen, 2 feet out from the trunk. Water the aspen again enough to fill the dam.
Apply a 3-inch layer of wood chip mulch to the base of the tree, but do not cover the trunk.