by Sara Williams
Saskatchewan Perennial Society
Looking for trees that are a bit unusual but have been tested for winter hardiness on the prairies? As I mentioned in part 1 of this article, the Western Nursery Growers Group established four test sites across the prairies, including Saskatoon, where “new” (and sometimes old) tree species and varieties were tested from 2008 to 2016. For additional information, see their website: www.prairietrees.ca. Here are more trees hardy to zone 2 and recommended for Saskatchewan.
‘Dropmore’ linden (Tillia flavescens ‘Dropmore’)
A hybrid of the American linden (Tillia americana) and the little leaf linden (T. cordata), the ‘Dropmore’ linden was introduced by Frank Skinner of Skinner’s Nursery in 1955 and named for the then closest post office that served the nursery. A strong grower of about 50 x 35 ft, it has a dense conical form and has performed well and consistently across the prairies since its introduction. It has fragrant flowers in mid-summer, yellow fall colour and is resistant to the linden leaf gall mite
‘Lone Star’ linden (Tillia cordata)
Keeping lindens in the family, Frank’s son, Hugh, introduced ‘Lone Star’ in 2018. Hugh selected it from a row of little leaf seedlings in 1982 and it has since been tested extensively across Canada and the United States. Derived from a Swedish race of little leaf linden, ‘Lone Star’ is about 40 x 25 ft with a dense symmetrical canopy and pyramidal form and needs little pruning. The flowers are much visited by bees and the green heart-shaped leaves turn golden yellow in fall. It thrives in full sun to partial shade. Once established, it’s adaptable to various moisture and soil conditions
‘Navigator’ pear (Pyrus ussuriensis)
A selection of the Ussurian pear, ‘Navigator’ is 35 x 20 ft, with a dense, conical to pyramidal form. It has gorgeous white flowers in early spring that emerge before the leaves, making it an excellent ornamental as well as a pollinator for hardy edible pears (unfortunately ‘Navigator’ pears are not for eating). The dark green foliage shifts from yellow to red in fall. Place it in full sun. Adaptable to various soil types, once established it is quite drought-tolerant.
’Shooting Star’ Northern pin oak (Quercus ellipisoides)
About 40 x 30 ft, northern pin oaks are excellent, long lived (up to 100 years) shade trees with furrowed gray bark and green glossy foliage that turns a brick red in fall. They’ll grow in full sun to partial shade. Pyramidal to oval in form, they are relatively fast growing and prefer average to moist soil. But because they are grafted onto bur oak root stock, they are more tolerant of drier, high pH soils.
‘Top Gun’ bur oak (Quercus macrocarpa)
Bur oak, native to the eastern prairies, is tough and long-lived. With a dense, spire-like, narrowly upright form of about 45 x 15 ft, ‘Top Gun’ is ideal for a narrow space. Its branches are shorter rather than upright. The large, dark green lobed leaves turn yellow in fall. The bark is corky and gnarled. It produces large acorns. It can be grown in full to partial sun, dry or moist sites and various soils.
‘Regal Celebration’ Freeman maple (Acer x freemanii)
Here is a selection from a population of natural hybrids of silver maple (Acer saccharinum) and red maple (A. rubrum) from Ontario and Minnesota’s Lake of the Woods area that has proven hardy in zone 2. Seedless and more tolerant of high pH soils, ‘Regal Celebration’ is an excellent shade tree of about 40 x 30 ft. It has furrowed grey bark and green lobed leaves that turn an outstanding early red fall colour. Grow it in full sun in average to moist soil.
‘Delta’ Hackberry (Celtis occidentalis)
‘Delta’ hackberry (44 x 40 ft) is a great but much under-appreciated shade tree that tolerates alkaline soils and urban stress. Although somewhat similar in appearance to elms, it is immune to Dutch Elm Disease. Originating from a seed strain from the Lake Manitoba’s southern shores, it has warty gray bark. Grow it in full sunlight to partial shade. Once established, it is adaptable to various soils and moisture conditions.
Sara Williams is the author and coauthor of many books including Creating the Prairie Xeriscape, Gardening Naturally with Hugh Skinner and, with Bob Bors, the recently published Growing Fruit in Northern Gardens. She continues to give workshops on a wide range of gardening topics throughout the prairies.
This column is provided courtesy of the Saskatchewan Perennial Society (SPS; firstname.lastname@example.org). Check our website saskperennial.ca) or Facebook page (facebook.com/saskperennial). All Saskatchewan Perennial Society events are on hold until further notice.