Family: Salicaceae

This Tree in Colorado: Aspen is one of Colorado's most popular trees, especially at this time of the year. Its fall color, contrasted against the green coniferous forest and deep blue sky, is splendid and draws thousands of people to the Rockies each fall. Brilliant yellows with occasional tinges of reds and oranges excite the visual senses. The soft light-green to creme white bark accented with dark ridges outlining branches make this tree especially attractive. So much so that many people want to bring this beautiful tree into their urban yards. Aspen is a "pioneer tree." It grows quickly after forest disturbances like fire, landslides, and logging. In urban areas, growing aspen in tilled areas is usually best and provides an opportunity to have a grove of trees. Aspens easily sprout from its existing roots. Aspen is beautiful but it comes with an abundance of problems for the home landscape setting. Be thoughtful in its placement and planting.

Growth Rate:  Accent plantings at the corners of homes. It can be a small shade tree for patio or deck. It is not recommended to plant it singly but in groups. It's mountain beauty doesn't transfer as well to the urban landscape. Leaf color doesn't have the same impact as seen in the mountains. The many diseases associated with aspen are enhanced in the urban setting. Again, it is important that a planting site protected from the encroachment of grass sod be considered. 

Landscape Use:  Accent plantings at the corners of homes. It can be a small shade tree for patio or deck. It is not recommended to plant it singly but in groups. It's mountain beauty doesn't transfer as well to the urban landscape. Leaf color doesn't have the same impact as seen in the mountains. The many diseases associated with aspen are enhanced in the urban setting. Again, it is important that a planting site protected from the encroachment of grass sod be considered. 

Best Advice: It is best to plant aspen in protected zones of the yard. Do not plant in the lawn. Aspen has very thin bark which is easily damaged by lawn mowers, weed whips and other equipment. By planting in "beds," the roots are able to sprout new trees periodically. It is possible to keep an aspen "grove" growing forever. Remove the older, less healthy trees.

Hardiness:  Zones 1 to 6. A wide range. Aspen is the most widely distributed tree of North America.

Leaves: Simple, thin, ovate about 1 1/2" to 3" long and wide.. On a long flattened petiole about 1" to 21/2" long.   Margins are finely serrate (dull sawtooth). When there is a slight breeze, the leaves "tremble."  

Flowers:  Insignificant. Few aspen are regenerated from seeds, in the west.

Bark: Green-white to creme colored. Becomes furrowed on older trunks.

Insects and Disease:  Abundant. The most common insect would be oystershell scale which can be controlled with a Teflon pad and actually removing the insects. Leafminers, mites, aphids, and leafrollers are also common. Diseases probably affect the tree the most. Stem cankers and leaf spots are prevalent. The best practice is to clean up the leaves and dispose of them in the autumn.

Information Sources:  Dirr, Michael Dr., "Manual of Woody Landscape Plants," 1990

             Kuhns, Michael Dr., "A Guide to the Trees of Utah and the Intermountain West,"1998

Leatherman, D., McNulty, H., Schomaker, M., and Lynch, D, "Aspen: A Guide to Common Problems in Colorado", Colorado          State Forest Service, CSU, 1986.