Colorado's climate makes apple trees a great choice in most gardens except for the high mountain areas. The fragrant pink blossoms make great showstoppers in your early spring garden, while the fruit that arrives later in the summer or fall works well for baking, ciders, canning or fresh eating.
Cross-Pollinating vs. Self-Pollinating
Most apple trees require cross-pollination, a natural process where insects such as bees transfers pollen from one blossom to another blossom from a different plant. This means that you need two apple trees in order to get them to cross-pollinate and bear fruit. If space is at a premium in your garden, plant one of the few self-pollinating apple trees varieties. These trees bear fruit all by themselves, but they will produce more fruit if they are also cross-pollinated.
Varieties of Apples
Depending on how much space your garden offers as well as your tree's cross-pollination requirements, most apple trees come in dwarf or standard sizes. The best apples trees for Colorado's climate include those with fruit that matures no later than the beginning of October. Consider growing Yellow Delicious, Red Delicious, MacIntosh, Gala, and Granny Smith for starters. Avoid Fuji apples since they require warmer climates.
Apples grow well in USDA hardiness zones three through eight, so make sure your garden falls into that range. (Find a link to a hardiness zone map in Resources.) They also require sunny locations where the danger of a late frost will not harm them. Plant the trees in full sun in well drained soil and--given Colorado's crisp falls--avoid planting them near buildings or other large trees that might hold pockets of cold air during late-season frosts. If your garden allows it, plant apple trees on small hills in the open so the sun can dry off their leaves if they do get hit by frost.
Once your apple tree shows 3 or 4 inches of new growth during its first summer, it's important to prune it back a bit. This encourages one branch to grow upward while the other branches grow outward. To prune, select one upright branch as the leader, then remove all the shoots within 4 inches of this branch.
Disease Prevention and Pest Control
Watch for powdery spots or mildew on the leaves, branches or blossoms of your apple trees. If you see this problem, you may want to spray a fungicide on your tree; continue spraying until mid-June. In Colorado, codling moths and other pests may cause problems in your trees. Consider spraying horticultural oil sprays in early spring when the trees are dormant. Later in the year, eliminate troublesome pests by hanging several sticky traps in the branches.