Deb Babcock: Mountain Ash a local favorite
September 23, 2012
One of the prettiest shrubs you see in the autumn forest across Routt County is the Mountain Ash (Sorbus scopulina) with its scarlet foliage and brilliant orange-red berries. It's a favorite of many local gardeners.
This slow growing deciduous tree thrives in regions from USDA Zones 2 to 6. (Our area is mostly Zone 4.) It can grow up to 20 feet high and wide but generally is in the eight- to 10-foot size here in Routt County. A member of the Rose family, it is found in the wild primarily along moist rocky north-facing hillsides (think Buffalo Pass), in our wooded forests, as well as at the edges of swampy areas.
Its common name is Greene Mountain Ash, named after botanist Edward Lee Greene who named more than 4,400 species of plants during his career in the late 1800s and early 1900s.
It flowers in May or June here and starts producing the beautiful berries in September and October, and they stay on the shrub throughout the winter months, providing color and food for birds and other winter animals. It is a particularly important berry for the survival of our grouse, robins, jays and squirrels. Moose and deer also get nutrition from all parts of these plants, including the leaves and twigs. For moose, these trees can provide more than half of their summer diet.
This native shrub features dense foliage consisting of alternate, compound pinnate leaves (divided along two sides of the vein like a feather) with nine to 13 oval, serrated leaflets attached to each stem. It is a dark green in the spring and summer, turning to pretty oranges and reds in the fall. The flowers are a cluster of small white quarter-inch blooms that turn to a beautiful clump of seeds in the fall.
The seeds are edible, though they taste bitter to humans and do contain a small amount of hydrogen cyanide (the stuff that gives almonds their flavor). Eating an excess of the berries could cause serious problems, including death. It is best to leave these to the birds and wild animals for winter feeding, or simply use them as fall decorations in wreaths and dried flower displays.
If you're interested in this plant for your garden, it grows in most any kind of soil — from beautiful loamy, organic material to clays with low nutrition — but prefers moist soil that drains well. Light can be partial shade to full sun. You can propagate it from seed, though it is very slow-growing, or simply transplant from the forest (get a permit first) or from one of our local garden centers.
Deb Babcock is a volunteer Master Gardener through the CSU Extension Routt County. Call 970-879-0825 with questions.