The American Mountain Ash, is a small, deciduous, understory tree (sometimes a shrub) that is native to northeastern North America from Newfoundland to Manitoba south to northern Illinois, northern Michigan and New Jersey plus further south in the Appalachians to Georgia. It typically grows to 15-30’ tall with an open rounded crown. It is noted for its attractive form, white spring flowers, serrate compound-pinnate leaves and bright orange-red fall fruit. Smooth, gray bark becomes scaly with age. Dense flattened clusters (corymbs to 3-6” across) of very small 5-petaled white flowers (each to 1/4” wide) appear in May. Flowers are followed by bright orange-red berries (each to 5/16” diameter) that ripen in late summer and remain on the tree after leaf-drop. Berries are attractive to birds and animals, but too acidic to be eaten fresh off the tree by humans. Berries may be made into jellies. Each odd pinnate leaf (6-10” long) typically has 9-17 sharply serrated, lance shaped, dark green leaflets (2-4” long) with gray-green undersides. Foliage turns yellow in fall. Mountain ashes usually have ash-like leaves, but are members of the rose family, and are not related to true ashes (Fraxinus), which are in the olive family. Best grown in moist, acidic, humusy, well-drained soils in full sun. As the common name suggests, this is a tree of cool mountain climates so it does well in northern regions. Lawn specimen or small shade tree for cool northern climates. Hardy in zones 3-6.
Growing Instructions for the American Mountain Ash
The seeds have a period of dormancy. They can be planted outdoors in the fall or winter for spring germination or they can be cold stratified to simulate winter conditions and to break their dormancy at any time of the year. 1. Soak the seeds in water for 24 hours. 2. Put the seeds in a ziplock bag. 3. Put the bag in the refrigerator and leave it there for 90-120 days. 4. The seeds like moist, well-drained soil. Prepare a mixture of half potting soil and half sand, perlite or vermiculite. Put the soil in a pot. 5. Sow the seeds on the soil. 6. Cover the seeds with a thin layer of soil. 7. Water the soil so that it is moist but not wet. 8. When the seedlings are a few inches tall, they can be transplanted.