Fall is here. Cold mornings bring forth crisp air and frost coverings. The garden is beginning show signs of preparation for the winter season. Most plants begin to shut down and go to seed. But there is one family of species that push their moment of glory until fading light of the growing season.
Asters are a wide ranging group of fall-blooming perennials that display an array of beautiful flowers. There are many species native to Ontario and they can often be seen fields, roadsides and natural spaces because of their ability to stand their ground against aggressive species such as goldenrod. Aster flower colour is primarily in the cool spectrum with a range from deep purple to clean white with the central feature of their daisy-like shape being a shade of yellow. They are a wonderful addition to the natural garden due to their late bloom period, soil adaptability and sporadic nature (self-seeding potential is very high).
Now each species that fits under the Symphyotrichum umbrella has it’s own slight trademark that brings a smile to the observant gardener.
Sky Blue Aster- Symphyotrichum oolentangiense
Among the latest blooming in the aster family, it boasts of an airy, soft blast of bluish-purple color. Each plant displays a multitude of small flowers that creates a three dimensional panorama look as they sit various points on multi-branching stalks. It is a welcome sight in fall garden either tucked in little pockets or massed among rocks and grasses.
The sky blue aster has a preference for dry soil and can survive quiet well (almost too well) without any special treatment. Full sun to a little shade will make this species happy. Keep note that it self-seeds aggressively. Fortunately, because of it’s slight stature it will rarely become overbearing and prefers to fill in a gap any chance it gets.
New England Aster – Symphyotrichum novae-angliae
The king of the aster family. Large, deep reddish-purple flowers with vibrant yellow centers are perched upon strong stalks. The New England is the most authoritative member with coarse features, an upright growing habit and it’s large mature size.
The New England is highly adaptive to dry to medium conditions and can stand it’s ground with aggressive species like goldenrod. Full sun is it’s favorite. It will self-seed with effectiveness and is probably the most boisterous aster in claiming new territory.
Swamp Aster – Symphyotrichum puniceum
The name gives away it’s trademark attribute- it enjoys soil with some moisture. Despite the fact it likes riparian habitats, it is actually quiet adaptable to medium soil conditions and will do well in most garden applications. Most akin to New England aster (would recommend using interchangeably depending how wet or dry a site is) with big bright flowers and strong branching characteristics. The swamp aster has a more cool bluish flower and a slightly softer appeal.
The swamp aster blooms with intensity in either full sun or part-shade conditions. Self-seeds well especially in wet conditions with little competition. It is very enjoyable and adds that extra dimension of to the gardener’s tool box with its riparian nature.
Lowrie’s Aster – Symphyotrichum lowrieanum
Consider this species to be the shade loving version of the sky blue aster. Dainty blueish-purple flowers with yellow centers are displayed with slightly more reservation than it’s counterparts but fulfills a duty rarely seen in the shadows- a purple aster. It prefers a medium to moist soil composition matched with low light levels that are typical of a woodland flowering species.
Calico Aster – Symphyotrichum lateriflorum
Miniature, white flowers appear all over it’s laterally grown stalks. A contrast to the blue’s and purples of it’s siblings the calico conjures up a textural appearance as opposed to colourful statement. The flower centers begin as a pale yellow and fade to a dull reddish-purple which creates a muted visual patchwork of varied color.
The calico is very adaptive to light conditions as it will grow in both ends of the spectrum if given dry to medium soil conditions. Notice the trend…? it also self-seeds quite well.
White Wood Aster – Eurybia divaricata
Although this species is not a Symphyotrichum member it displays all the visual characteristics of an aster. Clean white flowers are displayed in a vast array similar to sky blue aster. This handsome species prefers part shade with medium moisture conditions. It’s a great addition to that corner of a garden with lower light levels.
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