They are native to North America and are named after the Christian feast of St. Michael the Archangel, which falls on September 29th, around the time when these flowers typically bloom.
An easy to grow perennial, Michaelmas daisies are known to provide a late nectar serving in the garden, attracting butterflies, bees, and other beneficial pollinators.
So what do you need to know to keep asters happy in your garden?
Michaelmas daisies thrive in full sun to partial shade, generally requiring at least six hours of direct sunlight each day to ensure healthy growth and abundant blooming.
These daisies prefer well-draining soil that is moderately fertile. They can tolerate a range of soil types, including sandy or loamy soils but avoid planting in waterlogged or overly compacted soil.
Applying a layer of organic mulch around the base of the plants can help conserve moisture, suppress weeds, and regulate soil temperature. Use materials like compost, shredded bark, or straw, but keep the mulch away from the stems to prevent rot.
Michaelmas daisies prefer consistent moisture so water regularly, especially during dry periods, to keep the soil evenly moist. Aim to water at the base of the plant to avoid wetting the foliage, as this can lead to disease issues.
Deadheading spent flowers throughout the blooming season to extend the flowering period.
Pruning Michaelmas daisies is beneficial to maintain their shape and promote better blooming. In early spring, before new growth emerges, trim back the old, woody stems to encourage fresh growth.
Over time, Michaelmas daisies can become crowded and will benefit from division every two to three years in late autumn or early spring. Dig up the clump, separate it into smaller sections, and replant them in well-prepared soil.
Fertilise these plants in early spring with a balanced, slow-release fertiliser to provide them with essential nutrients. Follow the instructions on the fertiliser package for application rates.
While Michaelmas daisies are generally resistant to pests and diseases, they can occasionally be affected by powdery mildew, an unsightly fungus which can affect growth. Water the plant at the base, rather than overhead to prevent further spread, and add lots of organic matter to the soil to prevent it from drying out.
There are all sorts of great new varieties of Michaelmas daisies in a range of hues including purple, pink, red, blue, and white, all with a golden or orange eye.
Aster cordifolius ‘Little Carlow’ boasts large heads of violet-blue flowers with yellow centres, and fabulous dense, dark green foliage. Reaching around 90cm tall, it is ideal for the middle of a border.
Aster tongolensis 'Beggarten' is a compact, clump-forming plant, reaching a height of 40cm so is ideal for the front of a border. It will continue flowering until the first frosts.
Aster thomsonii ‘Nanus’ is a compact lilac daisy growing to a height of 45cm which starts to bloom from July onwards.