Green ash

The green ash (Fraxinus pennsylvanica) is perhaps the most famous and best known species grown on the prairies. Even those who are not gardeners should be familiar with this tree. As the name implies, this species does indeed grow in Pennsylvania and it was there that it was first named and identified. However, it ranges throughout the continent and usually grows in areas where moisture conditions are good. This is a very robust, highly adaptable species with bark that is smooth when young and becoming deeply furrowed with age. 60-80 ft. is the average height, and it is very fast growing. The pinnate, lance shaped leaflets are attractive and become brilliant yellow in fall. It is usually the last tree to leaf out in the spring and the first to drop its foliage when autumn arrives.

Green ash was planted extensively across the prairies in the early 1900’s and right into the 1940’s. Fast growing, highly adaptable, and untroubled by harsh winters or disease, the green ash soon found itself growing on nearly every farm, in nearly every shelterbelt, and in every small town and city. It was immensely popular, but after a few decades it became increasingly apparent that this tree was much too large for most urban settings and that it self seeded so prolifically as to make a huge nuisance of itself. The immense, spreading root system was also sometimes a problem, as were the hordes of caterpillars and leaf rollers that the foliage attracts. Eventually, green ash fell from popularity and many people developed a dislike for these trees. Anyone who has ever had to weed a flowerbed adjacent to a large female green ash will understand this. Eventually, several male selections of it were named and released to the nursery trade. ‘Patmore’ (selected in Vegreville, Alberta) is one of these, as is the very similar ‘Bergeson’.

In more recent times, green ash has slowly started to come back to the consciousness of gardeners and city planners. ‘Foothills’ is a cultivar selected near Calgary for its ability to tolerate Chinook winds. It is also a male selection and quite compact. ‘Prairie Spire’ was introduced by the University of North Dakota and has the most pyramid shaped growth habit of all the green ash. ‘Excel’ is yet another male clone that was selected for its much slower growth habit, making it less likely to outgrow a more confined space. 

Overall, green ash are better suited to farms and acreages than they are to city life. Zone 2.