Lots of preparation, patience and understanding are needed to grow aspen in the urban landscape. Aspen prefer light soils that are acidic and drain well, but these conditions are rarely found in urban areas. Aspen will do best on the north and east sides of buildings.
If the soil where an aspen tree is to be planted has a high content of clay, build a berm of sandy loam 18 to 24 inches high. A berm is a mound or wall of earth. The berm should be mulched and several plants should be planted in the bed.
Nearly all aspen available for sale are collected, meaning they were dug out of the wild with little of their root system. Even after careful preparation and care, aspen still only have a life expectancy of about 25 years in the home landscape.
Expect insects and diseases, some of which have no controls. Blackened leaves towards the late summer and fall are caused by aphid secretion or a leaf spot disease. The leaf spot disease is known as Marsonnina leaf spot or aspen leaf spot. The best control is to pick up the leaves, which are the source of reinfection, in the fall and cut away trees and branches to increase air circulation through the aspen.
Orange pimples on the bark indicate the presence of cytospora canker. Cankered branches need to be removed.
Oyster shell scale are tiny, quarter-inch-long brown or gray shells along the trunk and branches of aspen. This disease is caused by an insect that is difficult to control.
For more information, see the following Colorado State Extension fact sheet(s).
- Bacterial Wetwood
- Aspen and Poplar Leaf Spots
- Cytospora Canker
- Aphids on Shade Trees and Ornamental
- Oystershell Scale
- insect Control: Horticultural Oils
- Poplar Twiggall Fly
- Trees and Shrubs for Mountain Areas
- The Science of Planting Trees
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Updated Friday, April 19, 2013