An aspen grove is not actually a stand of independent trees, but actually one organism with a massive root system that shoots up trees from the root mass. Because of this, aspens are among the largest living organisms in the world. In the home landscape, a single aspen tree may not live 20 years. But with proper care, you can grow a healthy aspen stand that gives you years of enjoyment.
Select a location for your aspen tree with lots of sunlight and well-drained soil. Aspen trees do not do well in clay soil, but will thrive in all other soil types.
Purchase nursery-grown aspen trees. Trees grown in a nursery will have a more complete root system than trees that are collected from the wild. Wild aspen trees were harvested by being pulled out of the root mass of a larger aspen grove. These trees will not thrive as well because a large part of their root system was left behind.
Dig a planting hole for an aspen that it slightly wider than the aspen’s root ball, but is not any deeper. Planting an aspen too deeply can smother the roots and kill the tree. The upper roots of an aspen should be no more than 2 to 3 inches from the surface of the soil. Unwrap the root ball and discard the burlap covering. If aspens are potted, turn the container on its side. Support the trunk of the tree with one hand, and gently tap the container with the other to release the root ball. Place the root ball into the planting hole and gently cover with dirt.
Mulch with pine straw or pine bark to preserve water. Pine straw and bark are slightly acidic and will help to gradually lower the soil’s pH. Aspens thrive in soil that is slightly acidic. Water deeply once per week to help your trees become established. The soil should feel as damp as a wrung-out sponge.
Prune the inner branches, dead branches and spindly growth of your aspen tree to open up the canopy and increase circulation. This will help your aspen become more resistant to fungus and mold. To prune, lop off branches with a sharp pair of branch loppers. Branches should be cut at a 45-degree angle away from the tree near the trunk. You should also remove any branches that produce an orange, pimple-like canker. These branches are diseased with cytospora canker. Removing the branches helps to stop the spread of disease.
Release beneficial bugs such as ladybugs around aspens to control mites and aphids. If you find scale insects on your aspen trees, you can spray them with horticulture oil.
When a tree begins to show signs of decline, such as deadwood and a thin crown, you should remove the tree to make room for younger aspen that have sprung up from the root system.