It s not a drought-tolerant tree. This is true for most of the Great Plains, where trees evolved to be near a streamside. After all, the Plains were covered with grasses and wildflowers. The mountains differ vastly. There you ll find aspen thriving on a mountainside, which allows water to run downhill alongside the roots.
Aspens prefer mountain temperatures and hilly terrain to having roots sit in water on flat land.
Neither cottonwoods nor aspen will grow spectacularly well without extensive irrigation. Other gardeners will coax ponderosa pine and blue spruce at lower altitudes. Blue spruce requires more water than the ponderosa pine, which is most comfortable set apart from rather than in the middle of lawns. Too much water from frequent lawn watering will stress their roots and they ll become fragile. These plants require more water than the dry Plains.