American Mountain Ash Tree Seeds | (Sorbus americana)

Brilliant orange-red berries. White spring flowers. Wildlife essential in northern forests.

Sorbus americana, the American Mountain Ash, is one of the most ornamentally complete native trees of the northern forest, producing flat-topped clusters of creamy white flowers in late spring, brilliant orange-red berry clusters that develop through summer and persist through fall and winter, and brilliant orange to red fall foliage that creates a three-season display without parallel in cold-climate native trees. It grows naturally in the boreal forests of Canada and the northern Appalachians where its fruit is one of the most important winter food sources for cedar waxwings, robins, and other fruit-eating birds. Despite its common name it is not related to true ash but is a member of the rose family, more closely related to apples and serviceberries. If you are looking to buy American Mountain Ash seeds or grow this northern native from seed, this is the tree for cold-climate gardens where four-season ornamental value in a native plant is the goal.

• Brilliant orange-red berry clusters developing in summer and persisting through winter as critical wildlife food
• Flat-topped white flower clusters in late spring attractive to native bees and pollinators
• Brilliant orange to scarlet fall foliage, one of the finest fall color displays of any northern native tree
• Critical winter food tree for cedar waxwings, robins, and other fruit-eating birds in boreal and northern forests
• Cold-hardy to zone 2, one of the most ornamental native trees available in very cold climates

Things you probably did not know about the American Mountain Ash

Cedar waxwings travel specifically to fruiting Mountain Ash trees and can strip an entire tree in a day. Cedar waxwings are one of the most fruit-specialized birds in North America and form large winter flocks that locate and exploit fruit crops systematically. A large American Mountain Ash loaded with berries can attract a flock of hundreds of cedar waxwings that, working together, can remove all visible fruit within a single day. The event is one of the most dramatic wildlife spectacles available to northern garden observers.

The berries are mildly toxic when raw but safe when cooked. Mountain Ash berries contain parasorbic acid when raw, a compound that causes digestive irritation in humans if berries are consumed in quantity without processing. Cooking or fermenting destroys this compound entirely, and cooked Mountain Ash berries have been used for jelly, wine, and liqueur in Scandinavian and northern European folk traditions for centuries. Birds are not affected by the raw berries and consume them freely.

It is one of only a few native trees that grows naturally above treeline in the highest Appalachians. American Mountain Ash grows at higher elevations than almost any other native tree in the eastern United States, reaching the krummholz zone near the treeline on the highest Appalachian peaks where harsh conditions, ice damage, and short growing seasons prevent most other trees from establishing. The prostrate, wind-sculpted forms found near treeline represent the same species as the upright garden specimens growing thousands of feet lower on the same mountains.

The berries are used to make a traditional Scandinavian aquavit. In Scandinavia, the closely related European Mountain Ash, Sorbus aucuparia, has been used for centuries to flavor aquavit and schnapps with a bitter, complex flavor that is considered a traditional northern specialty. The same technique using American Mountain Ash berries has been practiced in northern North America and produces a similar product. The berries must be harvested after the first frost when the parasorbic acid has degraded naturally.

Growing Details

• Botanical Name: Sorbus americana
• Stratification: Required, 90 to 120 days cold stratification
• USDA Zones: 2 to 5, not well-suited to hot summer climates
• Soil: Moist, well-drained, slightly acidic
• Light: Full sun to partial shade
• Height: 15 to 30 feet
• Spread: 10 to 20 feet
• Growth Rate: Moderate, 1 to 1.5 feet per year

Plant it in a cold northern garden where the combination of white spring flowers, orange summer berries, red fall color, and winter bird visits will make it the most-watched tree on the property across every season.