Asters! Manitoba's Fall Wildflowers

By Doug Collicutt

(Click thumbnail images for larger photos.)

Introduction

Summer’s over. Gone is the heat, humidity and mosquitoes; replaced by the cool nights, brisk days and changing colours of autumn. And along with summer’s end, come some of my favourite wildflowers, the asters. I’m particularly fond of asters, as they are the harbingers of autumn, my favourite season. From mid-August until well into October there will be asters of some sort blooming in Manitoba.

Biodiversity

According to Manitoba’s Conservation Data Centre there are 23 different species of asters occurring in our province. Virtually every habitat type in the province has some kind of aster living there. In sunny meadows or disturbed areas Smooth Aster (Aster laevis) and Many-flowered Aster (A. ericoides) are abundant. In moist prairies New England Aster (A. nova-angliae) stands tall. In marshes and wetlands: Willow Aster (A. hesperius) and Flat-topped White Aster (A. umbellatus). In forest glades: Lindley’s Aster (A. ciliolatus). In boreal forest wetlands: the Purple-stemmed Aster (A. puniceus). In sandy prairies: the rare Western Silvery Aster (Symphotrichium sericeum).

Biology of Asters

Asters take their name from both the Latin and Greek words for star. They are members of the Asteraceae, the family of plants also known as the “composites”. This is owing to the nature of their flowers. What appears to us to be a single flower is, in fact, a composite of many tiny whole flowers. Think of a tall spike of flowers that has been squished down into a flat disk, with each of the flowers within the disk having lost their petals and those on the outermost rim of the disk having just one petal each; that’s a composite flower.

All our asters bloom late in the year, from mid-August until early October in some species. By flowering late they attain the full attention of the pollinating insects that are still around. Bees, butterflies, beetles and other insects are still looking for food at this time of year; in fact many are dependent on the pollen and nectar they find at this time of year to put on fat for their coming hibernation. Monarch butterflies (that don’t hibernate, but migrate instead) are very dependent on available nectar supplies to fuel their prodigious migration to central Mexico, which they reach by late October.

Grow Your Own

Native asters can help keep your garden in bloom well into the fall. There are several local suppliers of native plants in Manitoba, and even some of the major nurseries now carry some native wildflowers, including asters. I hope you’ll resist the temptation to remove plants from the wild. Most plants don’t do very well when transplanted from the wild and you may end up introducing unwanted plants into your garden along with the clump of soil containing the plant you do want.

I prefer to grow my own new plants from seed, and asters are quite easy to propagate. Asters produce small fluffy seed heads that look like tiny dandelion seed heads. Collect some seeds in the fall and store them in a paper bag for the winter. The seeds will benefit from stratification before planting. In March, take some of the seeds and put them in a small plastic bag with a damp paper towel, and put them in the fridge for 4 to 6 weeks. Then plant them on a moistened and well-compacted soil-less mixture. Just spread some seeds on top of the mixture and tamp them down, don’t bury them with more mixture. Light is important for the germination of most native plants. Cover the planting container with clear plastic to keep the surface and seeds damp. As with most native plants, the seeds may take a while to germinate, 2 to 3 weeks until germination occurs is not unusual, so be patient. You can thin out or separate the seedlings and grow them on until they are big enough to place into your garden. Some species will grow rapidly and flower in their first growing season, but most, like most perennials, will take a year or two to reach maturity.

Which aster to grow may be as important as how to grow them. Most native wildflowers will do well in garden settings, but some do too well! What was in the wild a small delicate plant, may end up being a monster in the garden. Smooth Aster is a case in point. This is probably the most common aster species in southern Manitoba; it readily invades disturbed sites and roadside ditches. In the wild it may grow to half a metre high and sport a couple of dozen bright blue flowers. Unleashed into a garden it may grow to a metre in height AND width, and be covered in hundreds of flowers. Now, it can be very attractive as such in a garden, but it may end up sprawling over and crowding out much of the rest of your garden, too. My favourite for the garden is New England Aster. It has an upright growth form; it won’t sprawl around, and it produces lots of large, purply-blue flowers starting in mid-August and lasting well into September.

In Closing

So, for late season colour in your garden, and to give our bees and butterflies a boost to help them through winter, or on their way to warmer climes, try some of our native asters in your garden.

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More aster articles in NatureNorth: Asters - Fall Wildflowers | Star Flower - a New Age Tale