Sometimes you think you know a plant only to find there’s far more to it than you realised. Asters – commonly known as Michaelmas Daisies – are such a plant.
To many gardeners they are those mauve daisy-like things that flower in autumn and grew in their parents’ garden. They have a slightly old-fashioned image and are generally seen as a filler in the border rather than a star.
Yet, the colour range is vast from cool white through to claret and it’s possible to have them in flower from early September to almost Christmas.
I was reminded quite how interesting asters can be at the Malvern Autumn Show where a display by Old Court Nurseries, holders of the National Collection, won gold.
It’s been some years since I visited Old Court and its display beds in The Picton Garden and I’d forgotten what a spectacle a mass planting of asters makes.
The display had a lightness and grace that is rarely associated with other autumn bloomers, such as rudbeckia, helenium or helianthus, and was something different to the usual yellows and oranges so often associated with the season.
Deciding it was time to rediscover asters, I attended at talk by Helen Picton hosted by Allomorphic in Stroud.
From the outset, it was clear there’s more to asters than mere mauve. A bucket of flowers, cut that day from the nursery, had white, pale pink, deep purple and some with a hint of red.
What’s in a name
And if the sudden realisation of the choice available wasn’t confusing enough, there’s the name. Work by botanists has led to many being reclassified and they are no longer called asters; nearly all the North American species are now Symphyotrichum or Eurybia.
Helen, who has a degree in botany, skipped through the explanation with ease but, perhaps realising that the switch is going to take some time among their customers, the nursery is still using the term aster as well as the new name for its plants.
She is the third generation of the Picton family to run the Colwall nursery, which was founded more than 100 years ago by Ernest Ballard, one of the first people to specialise in Asters.
The National Collection was started by her parents, Paul and Meriel, with many varieties owing their survival to two Bristol enthusiasts who collected them; their plants joined those at Old Court in the 1980s and today the collection has more than 400 varieties.
Asters do have a reputation for being prone to mildew that can turn their leaves an unattractive grey.
We were told that the novi-belgii group are the most susceptible, not least because they are shallow-rooted and therefore dry out quickly during the summer.
Helen suggested a garlic foliar spray was one method of treatment – though it is essential to cover all the foliage – and division every three years would help to keep plants vigorous.
Varieties with smooth leaves were more likely to get mildew than those with rough leaves, she added.
The majority need open, sunny positions to flower well, although a few are tolerant of shade.
Other cultivation tips included hiding the “naked bottoms” of the New England asters.
“They are definitely back of the border plants. Give them a nice skirt of something more interesting.”
What to choose
If you’re looking for something that will be smothered in flowers, the compact ‘Gulliver’ is a good choice. It grows to around 45cm and has mauve blooms.
Another small aster is ‘Purple Dome’, which again gets to around 45cm high, and has large purple flowers.
“It needs as much sun as you can give it,” advised Helen.
For arching flower sprays, Helen recommended the species asters, such as ‘Photograph’, which has smaller, pale blue flowers
“It is more relaxed in habit and mixes better with other perennials.”
‘King George’ had a rapid name change after it was introduced as Kaiser Wilhelm in 1914 and is now a popular variety. Its large purple flowers are loved by hoverflies and butterflies. Upright growing, it is mildew-free but needs good winter drainage.
One of the blowsiest is ‘Fellowship’, which has masses of pale pink double flowers. It grows to around 100cm and is one of the more mildew-resistant of the New York asters.
And, if you want something to tumble over a retaining wall, ‘Snow Flurry’, the only prostrate aster, might be the answer. It has long, horizontal flowering stems that are covered in tiny white flowers.
• The Picton Garden and the National Collection of autumn flowering Asters and related genera is open until mid-October. For details and more information on Old Court Nurseries and growing asters see here
• The next in the Allomorphic series of lectures is on November 11 when nurseryman Bob Brown of Cotswold Garden Flowers will be talking about his favourite plants. More details here