How to grow Asters

The scientific and botanical names for this lovely flower include Aster, Callistephus, Eurybia, Kalimeris, Symphyotrichum.

However, you may find the following names more recognisable: Michaelmas daisy, aster, China aster, and New England aster.

They get the name ‘Michaelmas daisy’ because they are often seen blooming around the time of the feast of the archangel Michael, at the end of September. There is even an old rhyme which features this explanation.

It goes: ‘The Michaelmas daisy, among dead weeds, Blooms for St Michael’s valorous deeds. And seems the last of flowers that stood, Till the feast of St Simon and St Jude.’

Plants of the Aster genus are most commonly native to Europe and Asia, however, there are a couple of varieties native to North America.

The name ‘Aster’ has origins in ancient Greek! ‘Asteri’ translates roughly to ‘star’, and so the flower got its name thanks to its starlike appearance.

There is even a Greek myth surrounding the origin of Asters, the flower being the product of the goddess Asterea’s tears.

Asters share a striking resemblance to daisies but in a fantastic variety of colours. The flowers emerge from a clump of sea-green leaves on dainty stems.

The blooms can come in pink, lilac, purple, red, blue, or classic white.

Asters prefer slightly moist soil, so anything that can retain moisture well. They enjoy full sun but can grow well in dappled or partial shade too.

Well-drained soil is best avoided, as if the soil dries too much the Aster will struggle. There is also a chance waterlogged soil could be problematic. Also, Asters prefer not to be in too much deep shade.

Know which Aster you are growing. Recently, many varieties have been reclassified under a different genus name, and these have different growing requirements. For example, Tripolium varieties have more succulent leaves, so require less frequent watering.

Most aster varieties flower from mid-summer to mid-autumn, with many varieties first flowering in late September. They will continually bloom until mid-autumn, which can be promoted by deadheading faded flowers.

Yes, Asters are great for pollinators. They provide a late-year supply of pollen, as they flower in late September.

There is a variety of Aster for many different purposes and locations in the garden. There are some taller varieties which are perfect for some colour at the back of your borders.

Shorter varieties are ideal for growing in containers, and those that are hardier for changing weather conditions. Clump forming is also great, as they will fill your container with a lovely colour.

There are even varieties of Aster that will perform wonderfully in a rock garden. Thanks to their origin in mountainous areas of Europe and Asia, they grow well in these conditions.

Even if you want to grow Asters to use as cut flowers, either for your own displays or as gifts, there are plenty of ideal varieties. Aim to grow Asters with long, upright stems, which will grow well for cut flowers.

This completely depends on the variety that you choose. The average variation in height is anything from 40cm (16 inches) to 1.2 metres (4 feet) in height. Spread is a little more consistent, sitting at roughly 45cm (1.5 feet).

First, you want to plant your Asters in early spring, between March and early May, depending on the hardiness. Try to make sure any risk of frost has passed. This will give them plenty of time during the growing season to establish before flowering in autumn.

You can also grow Asters from bare-root, which you will want to plant as soon as possible after they are delivered.

To plant your Asters in the garden, start by digging in some peat-free garden compost or well-rotted organic matter into your soil. This will improve your soil structure and fertility.

If you’re growing in containers, first choose a container at least 20-23cm (8-9 inches) in diameter, to give your Aster plenty of room. Use peat-free, multipurpose compost, and then position your container somewhere warm and sunny.

In the ground, water your Asters well after planting. Make sure the soil around the roots is constantly slightly moist, but not waterlogged. The amount of water your Aster gets can impact how tall it grows. If growing in containers, water more regularly. If the weather is particularly hot, it is likely that you will need to water them daily.

Overall, Asters don’t require feeding too regularly. However, mulching any garden borders every spring should be more than enough to keep them fertile. Use well-rotted organic matter, or peat-free garden compost to mulch.

Many varieties are very hardy in the UK, so don’t require too much attention to overwinter. However, your Asters getting too wet in the winter is more likely to cause problems. Lifting and dividing your Asters every three to five years is advantageous and is best done in early spring.

Asters are prolific flowerers, but if you want to encourage more flowering, deadhead any faded flowerheads. This is particularly helpful if you are growing China asters (Callistephus chinensis).

There are some varieties of Asters which benefit from cutting back in late May or early June. The technique for this is called the ‘Chelsea chop’, so called because the date corresponds with the famed flower show.

If you are growing any particularly tall Aster varieties, it may become necessary to stake them. Try to find out if the variety you are growing is projected to grow to over 1 metre (3.3 feet). If it is, consider putting some support in before the middle of summer. Symphotrichum novi-belgii is a great subject for this and performs well as a result. To do this, cut back the clumps to between one-third and a half of its previous size. This means the plant is less leggy, is less likely to require staking and produces a higher volume of blooms.

There are a couple of different methods for propagating Asters. Every three to five years when you divide them, you can propagate the clumps separately, producing more individual plants.

Otherwise, you can propagate via softwood cuttings between April and August. This process can over 2 years to produce flowering plants.

To propagate by cuttings, remove any non-flowering shoots, and the lower leaves of your cutting. Push into moist but gritty compost, and cover with a clear plastic bag. Make sure the compost is moist regularly.

Within six to eight weeks, you should see signs of growth from your cuttings. At this point, you can pot your cuttings into their own individual containers. Then, plant them out in spring. You should see flowers from them the following year.

The most found problem in Asters is powdery mildew. You can purchase mildew-resistant varieties, and you may find Symphotrichum novi-belgii Asters to be the most vulnerable. When watering, avoid spraying the leaves. Try to grow your Asters in moisture-retentive soil if you can and ensure the soil doesn’t dry out.

Within six to eight weeks, you should see signs of growth from your cuttings. At this point, you can pot your cuttings into their own individual containers. Then, plant them out in spring. You should see flowers from them the following year.

Here are some great Asters to grow at home for different parts of the garden:

You can buy asters in garden centres from mid-to-late spring, which you can plant out straight away once any risk of frost has passed. Otherwise, you can purchase them already flowering in late summer to early autumn. You will need to water them regularly to help them establish.

Asters grow well in cottage, prairie, and mixed garden designs. Some varieties also grow well in rock gardens.