For many, the beginning of fall is signaled by the appearance of pumpkin spice lattes. But gardeners might take more notice of the rows of mums appearing outside every box store in the valley. If you like mums, but are tired of purchasing them year after year, consider the Aster. As one IBG gardener likes to call them, “the harbingers of autumn,” are just now coming into bloom. Reliable, hardy perennials, Asters provide a burst of late fall color as well as a last stop for pollinators before winter. Asters come in a variety of colors and sizes, and require very little upkeep. The only challenges with Asters are that many are susceptible to powdery mildew and taller varieties can become unwieldy; however, both of these problems are overcome by selecting the right variety.
A favorite variety of Aster here at the garden is ‘Purple Dome’. Aster novae-angliae ‘Purple Dome’ is an all-purpose Aster whose scientific name means “of New England”. Unlike New York Asters (Aster novae-belgii) New England Asters have thick stems and hairy leaves, and are generally taller. ‘Purple Dome’, however, has been cultivated to maintain a low, bushy habit, making it easier to care for than taller asters that might require staking. Covered in deep lavender flowers, this cultivar generally blooms from late August until frost. As an added, bonus, ‘Purple Dome’ is mildew resistant.
Another low grower is Aster x frikartii ‘Monch’. Compact, but resplendent with light lavender blooms all fall, ‘Monch’ typically grows to only two feet tall, making it a perfect plant for a perennial border, and is also resistant to powdery mildew.
Possibly the best thing about Asters is that, to keep them looking their best, they need to be divided every two to three years; this means, of course, free plants! After your initial purchase, you will have access to a continual supply of these hardy perennials forever!
If you want to learn more about dividing plants, come to our education class, “Divide and Conquer” at IBG on September 29th.
If you’re in search of an Intermountain native option in the world of Aster, Machaeranthera canescens, commonly known as hoary tansyaster or hoary aster might be just what you’re looking for. It is a highly variable species that occurs throughout the western portion of North America as well as in some north central states. It can be found in a wide variety of habitats, and is particularly common in dry and/or disturbed sites, shrub steppes, and meadows. It is native to the Boise Foothills and is one of the few late summer flowering plants in this region. It is considered a short-lived perennial, but it often acts as an annual or biennial. Its latin name “canescens” refers to the small, gray hairs that cover its stems. Its leaves are long and narrow and often have sharply toothed margins. Flower heads appear singularly or in multiples at the ends of branches. A series of small, light green bracts form a cup below each flower head. The flower heads consist of disc florets that are a striking yellow color and ray florets that are pale to dark purple.
Hoary tansyaster can be found throughout the Lewis and Clark Native Plant Garden, as well as in the Foothills Native Plant Garden, along the Wilderness Trail, and in our restoration areas.
So, if you’re looking to get more bang for your buck year after year, and desire a more naturalistic option than mums, consider choosing an Aster. You’ll love the color it adds to your fall garden, and the pollinators will thank you, too!