Colorado's native soil is known as expansive clay, meaning it will expand and contract according to moisture content. Add to this Colorado's high-intensity sunlight, low humidity and winds, and you have challenging conditions for the state's gardeners. Landscape horticulturists at Colorado State University suggest gardeners consider only those plants that can tolerate these conditions, and apple trees are one of those plants.
Choose a location to grow the apple tree. Avoid areas that are lower in elevation than the surrounding landscape. This is especially important in Colorado, as frost tends to settle in these areas (called frost pockets), which can be damaging to apple tree blossoms. You will also need a sunny site.
Remove any turf and weeds from within a 3-foot wide circle around the tree. Other plants will compete with the young apple tree's roots for water and nutrients.
Amend the soil in the planting area by mixing a 4-inch layer of compost into the existing soil to a depth of 12 inches. A long-handled gardening fork is an appropriate tool for this task.
Dig a hole that is deep enough to allow the apple tree to sit 1 to 2 inches higher than it did in the nursery. In Colorado clay soil, this will allow the roots better air circulation. The hole should be twice the diameter of the root ball.
Place the tree's roots in the hole and backfill halfway with soil. Add water to the hole until it is full, wait for it to drain and continue filling the hole with soil. The top inch to 2 inches of the root ball should be above the soil.
Water the tree until the water puddles. When it drains, lay down a 3-inch layer of mulch extended in a circle, 3 feet from the tree. Don't allow the mulch to touch the tree's trunk.
Supply 2 to 3 gallons of water every two weeks. The apple tree may need additional water if the Colorado winds kick up, which can dry the soil quickly.
Prevent fire blight on apples damaged by hail by applying a streptomycin spay within 18 hours of the damage occurring, according to scientists at Colorado State University.