This protection may not work in dry, windy environments such as Doney Park, Fernwood, and Timberline. I live in Timberline and our house had seven aspens when we moved in. It was quite a challenge to water them and keep them disease free. We have lost two of them to cancer fungus in the fifteen years we’ve lived here, and their leaves develop large black spots every fall. If we had carefully removed all fallen leaves and debris, our trees might have avoided the black leaf spot (Marssonina spp.).
Remember that in the wild, these trees are adapted to sprout quickly after a fire or other disturbance – often from underground, living roots. They grow quickly and protect seedlings of other species such as fir, spruce, and pine. Once the trees are fully grown, the aspens themselves become shaded and usually die out. (However, the roots live indefinitely). Aspens are relatively short-lived and often only last five to twenty years in native landscapes. In addition, their widespread root system sucks heavily, creating new trees. Tiny new trees all over your landscape look like weeds. My husband ends up on aspen suckers several times each summer.
If you do decide to plant aspens, work on promoting healthy root systems by waiting until the top layers of soil feel dry before watering. Then water each tree until the top 18-20 inches of soil is damp. When pruning, be sure to use sharp, disinfected tools and immediately cut outside of the branch collar to ensure proper healing. Always prune sick and dead branches.
