ASTER: Michaelmas Daisy
Asters belong to one of the largest, most diverse flowering plant families, Asteraceae. They have evolved to utilize insects and wind for extremely efficient pollination and seed dispersal. (Just think of the dandelion!) Asters are native throughout the globe with nearly fifty species native to the Pacific Northwest. In an effort to narrow this vast family, this article will focus on perennial species commonly used in the garden.
Along with mums (also Asteraceae) and salvias, Asters are the swan song of flowering color in the garden. Their bloom season typically starts in July/Aug and goes into September/October. There is a wide array of flower color and size as well as plant height. Asters are also easy to grow!
Aster dummosus: These beauties are compact and great for the front of the border (12-18” high). They are hybrids of A. nova-belgi. They are hardy to USDA zone 3. A couple varieties are ‘Professor Kippenburg’ and ‘Wood’s Blue’. Try using these in your fall containers with ornamental kales and grasses.
Aster x frikartii ‘Moench’ (Fricartii Aster): A very long blooming aster (summer to fall) with large lavender flowers. An offspring of A. amellus and A. thomsonii it grows to 24” high and 12-20” wide. Provide full to partial sun and regular water. Zone 4-9. This plant is delightful with Kniphofias and ornamental grasses.
Aster nova-angliae (New England Aster): This group includes tall, showy cultivars perfect for the back of the border or weaved in among shrubs. They are native to northeastern damp meadows. The cluster blooms show off August through September. Fabulous cut flowers. Hardy to zone 4. Some favorite varieties include:
‘Alma Potschke’- Hot pink thread-like petals on tall 4’ stems. A show stopper! The hot pink really pops against burgundy foliage plants such as Hibiscus acetocella or Physocarpus ‘Diablo’.
‘Honeysong Pink’- A new introduction with fine, soft pink petals. It reaches 4’ tall and wide. This color pairs so well with silver foliage plants such as Artemesia versicolor ‘Sea Foam’.
‘Purple Dome’- a compact grower to 18” high & wide, royal purple blooms are complimented by bronzy bracts. This one pairs beautifully with ornamental grasses such as Carex testacea and Pennisetum ‘Moudry’.
Aster nova-belgii (New York Aster, Michaelmas Daisy): These asters are similar to their New England cousins but shorter with smooth toothed leaves. Great cut flowers September to October. Growing 3-4’ high. Hardy to zones 3-9. Common varieties include ‘Purple Viking’ -dark purple flowers, ‘Loke Viking ’- hot pink, ‘Coombe Violet’ - lavender and ‘Margrethe Viking’ - white.
Aster pringlei ‘Monte Casino’ - Clouds of tiny white flowers set this aster apart from some of the other large flowered species. The airy texture of this plant makes it the perfect filler in the garden or vase. Grows 3’ high and wide, and is hardy to zones 5-9. This one blends well with Helianthus ‘Lemon Queen’ or darker bold foliage of Cannas.
Photo credits: Monrovia
Common name: Michaelmas Daisy
Origin: 250 species from throughout the northern hemisphere and South America.
Culture: Most garden asters thrive in well drained, full to partial sun and regular summer water.
Pests & Diseases: Asters are generally pest free. Powdery mildew & rust are the major diseases. If this occurs remove the infected foliage (if possible) and spray the plant with copper or other fungicide.
Less common problems with asters include verticillium wilt, leaf spot, and leafhoppers (which transmit disease).
Maintenance: Asters can commonly flop in the garden by the time they are blooming. To avoid this, simply prune back by one half to two thirds in early to mid June. This practice often results in more flowers as well.
Once the plants turn yellow in the fall, cut to the ground. Fertilize in spring with an all-purpose slow release food.
Propagation: Asters can be propagated by seed, division or cuttings all best done in spring. Seeds can be sown indoors two weeks before the last frost or directly outdoors after the last frost. Seed grown asters will bloom in their second year.
Division of thick plants will allow for more air circulation, which makes the plant less prone to powdery mildew. Use basal shoots or stems up to 2” long for cuttings. Keep cuttings moist until thoroughly rooted.