Wisconsin native, Showy Mountainash provides true all-season interest in our northern climate. White showy spring flowers give way to bright red, eye-catching fruit clusters throughout summer. The tree has reliable fall color and fruit persists during winter for birds to feed on. Not to be confused with a true Ash (Fraxinus species), this cold hardy native is a great small-scale tree in the landscape.
Wisconsin Native: Yes
USDA Hardiness Zone: to zone 3
Mature Height: 20-25ft
Mature Spread: 15-20ft
Growth Rate: Moderate
Growth Form: Rounded, small-scale tree
Light Requirements: Full Sun to Partial Shade
Site Requirements: Acidic preference, moist, well-drained soil
Flower: White spring flowers
Bloom Period: May
Foliage: Smooth blueish-green
Fall Color: Brilliant yellow
Urban Approved: No
Fruit Notes: Showy edible red fruit clusters
Door County, WI
Site in well-drained or moist soils, Showy Mountainash prefers a slightly acidic location. Native mostly to northern Wisconsin, it naturally occurs around bluffs, upland forests swamps and shores (sandy or rocky sites). A great choice for an ornamental small-scale tree, Sorbus decora reaches mature heights at about 20-25ft. It can be used in a screening, along roadways, as a lawn specimen or small shade tree. It does not tolerate dry conditions. Profuse spring flowering that gives way to beautiful bright red persistent berries really catches the eye in the landscape.
An important source of food for wildlife in winter and early spring, the persistent berries of Sorbus decora provide for non-migratory birds like grouse, robins and blue jays. Small rodents like squirrels will also use it as a source a food.
Showy Mountainash is very intolerant of drought, so be sure to site accordingly. It prefers loamy soil and does well in the northern part of the state and can if sited correctly thrive elsewhere. Be sure to keep soil consistently moist when planting and choose a sunny or partial shade location. Minimal pruning will be needed to keep good branch structure. After winter berries may fall onto nearby patios or sidewalks, this can be minimal as most are eaten by birds throughout the season.
A few issues may arise over the course of the tree’s life. Though long-lived there are some things to watch out for. Bacterial fireblight being the most common and detrimental, it causes scorched leaves towards the end of branches. Scab can also cause defoliation. Trees that are stressed by these diseases are more susceptible to insect issues like borers, aphids, sawfly and scale. Canker is also more commonly found in trees that already are under disease stress.
Edible for human consumption Showy Mountainash berries are mildly bitter but much more tolerable if cooked into a delicious jam. The common name Mountainash refers to the ash-like leaves and preference of a cooler, mountain climate. However, it is a member of the rose family and not the Fraxinus (our native Ash) species.
A great tree to plant in rich loamy soils, combine with other natives that thrive in the same habitat. Try shrubs/trees like Pagoda Dogwood, Common Witchhazel, Scarlet Elderberry (Sambucus racemose) and Musclewood in a mixed screen alongside Showy Mountainash. Use core native perennials like Canadian Columbine, Lady Fern, and False Solomon’s seal.