Quaking aspen

Populus tremuloides

Basic statistics: In the willow family, Salicacea. USDA Hardiness Zones 1 to 6 (you gotta love a tree that can go Zone 1!) General height from 20 to 50 ft; spread from 10 to 30 ft. Bloom is insignificant in early spring. Requires full sun and medium water. Typically has good fall color and attracts birds. Suggested use is for naturalizing as, otherwise, can be a high maintenance tree.

This wonderful tree gains its common name from the quivering attitude of its leaves in the slightest breeze. It also has the widest distribution of any North American native tree species. In fact, worldwide, there are only two other species of trees with wider natural ranges: the Populus tremula, European aspen, and the Pinus sylvestris, Scotch pine. (Silvics of North America, Populus tremuloides)

The quaking aspen is a pioneer species, which means it readily colonizes disturbed or bare soil. What that also means is full sun is pretty mandatory so it can be shaded out as other trees establish around it. This process is natural as they give way to successional species. It is considered a short-lived species; however, it is a colony tree establishing a clonal grove which can live a very long time indeed.

A natural aspen grove in the south valley of the Bitterroot Valley, Montana
© 2020 McNeill’s Tree Service

High in the mountains of Utah there is an aspen grove which has been determined to be in the range of 80,000 years old with some estimating the age to possibly one million years. The jury is still out as it is difficult to actually determine the age of the root system of this mammoth organism. It covers an area of approximately 106 acres. Individual stems within this clonal grove average 130 years, determined by tree rings. There is also documentation in the Rocky Mountain Tree Ring Research website of a 317-year-old individual located in rocky Mountain National Park, Colorado.

Now consider the urban or residential landscape. Many of our clients in this area, the Bitterroot Valley of Montana, have the impression this tree only lives 10 to 15 years. The extremely short life of an aspen planted in the landscape is determined by the care (or abuse) it receives. They have specific needs in addition to their growth characteristics. Establishing a grove, gorgeous in their natural setting, is less than endearing when the homeowner desires a highly managed and immaculate lawn. This is not the tree’s fault. In my opinion, nursery personnel and/or landscapers need to inform the client of the characteristics of this tree. This is a better option than selling a tree to a homeowner who doesn’t have a clue as to what may happen or simply telling people not to plant this species.

When asked about the desirability of planting aspens, we always let people know if they have the space to let an aspen grow naturally, establishing a colony, they will have better success and a longer-lived tree than if they plant one as a specimen in the middle of their lawn.

If they then try to control the ramets (the young stems produced from the main root system) that come up by using herbicides, they are poisoning the parent plant as well. My article on aspens goes into this conflict in more depth.

Outward visible signs of aspen borer activity.
© 2020 McNeill’s Tree Service
What the inside of an aspen stem can look like from larval feeding by the aspen borer.
© 2020 McNeill’s Tree Service

We also warn people this tree has the longest list of insect and diseases of any of our trees. That might be a slight exaggeration, but not by much. I believe this is one of the reasons it is listed as high maintenance. Again, if you let it be a grove, let it naturalize, you will have a self-perpetuating landscape where you only have to harvest the dead/dying trees that might be a hazard. If they can be left as habitat, so much the better. Plan your strategy for where this lovely tree would be best suited. Be honest with yourself as to whether you have the suitable environment for it.

Planted five, 4ft whips in 2012. Photo taken 2018. Just counted 56 stems in our mini-grove.
© 2020 McNeill’s Tree Service

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