Michaelmas daisies: late stars

I have always had a thing against asters, or Michaelmas daisies. Their plain central disk, with
the petals whorled obviously around it, have a certain charm but I've always found this daisy flower too unadorned and, as a result, uninteresting.

Until lately, I've almost resented their lack of even a hint of the bosomy, generosity that dahlias, spider chrysanthemums and tulips – my favourite garden flowers – all give you.

But this isn't entirely fair. Asters look good in the garden very late in the year. Varieties such as Aster amellus 'King George' and Violet Queen (syn. 'Veilchenkönigin') were in flower until the recent winds and rain blew them over.

These have been performing well for ages, with 'Violet Queen' in particular having looked good since August. The Aster x frikartii varieties, such as 'Mönch' and 'Wunder von Stäfa', flower earlier in the year and, helped by a bit of dead-heading, they bloom from July until October. Even after frost and snow, there are still asters that look good – such as A. pilosus demotus, Aster amellus 'Weltfriede', Aster lateriflorus, and Aster 'Calliope'.

Then there are the colours that many asters come in. Here, they score high in the autumn garden. I'm not so keen on the whites, including Aster novae-angliae 'Herbstschnee', whose individual flowers look exactly like a daisy, or the pastel colours such as the pale pink Aster novae-angliae 'Miss K.E. Mash' or 'Harrington's Pink'. These seem the most old-ladyish to me, the pinks reminiscent of blancmange.

And there is another problem with these forms: the petal colour is so close to the central yellow heart of every flower. I know my hero Christopher Lloyd sang the praises of the pink/yellow colour duo when it occurred in a garden, but it's definitely my least favourite. I also have reservations about many of the paler mauve asters (such as 'Barr's Violet'), on the same grounds. I don't like that white-mauve colour mix with yellow, either.

There are, however, some fabulous carmine pinks and deep rich purples among the aster family and it's worth seeking these out. Keep your eyes peeled for Aster novae-angliae 'Primrose Upward' in a bright, strong pink, or the brilliant deep pink A. novi-belgii 'Carnival'. I also love Aster novae-angliae 'Andenken an Alma Pötschke'. This gives us autumn flowers in one of my very favourite colours, a brilliant, bright magenta that contrasts well with the flower's centre. The more intense, deeper pink turns the yellow into gold; it then makes a good combination.

The same is true when the mauves shade into the darker purples. I like Aster novae-angliae 'Violetta', a deeper mauve than most, and love A. novi-belgii 'Cliff Lewis' in a proper, rich purple. A large clump of this fits in well in the purple border at Sissinghurst where pale mauves are purposefully excluded.

One also has to think about the overall plant form and its foliage. Aster novae-angliae 'Andenken an Alma Pötschke' stands out here with good, bright green leaves. Asters can be dull when not in flower – dark, dead green and rather scrappy (particularly when blighted with powdery mildew –see page three), but not this one. It flowers for a shorter season than many (only for two to three weeks), but it looks handsome before flowering and after if dead-headed. I often pick non-flowering stems of this as filler foliage for arranging.

Asters are well known for their exceptionally long vase life. Pick them and put them in a vase and – kept cool – they can last more than a fortnight. If you strip all the leaves below the water line and thin out the leaves up the stem a bit more, and put a drop of bleach in the water, it will maximise the cut-flower potential.

Asters tend to be over-used in old-fashioned church flower arrangements because of this durability, often the only colour amid a heavy background of evergreen leaves. But mix the rich purple and magenta colours in with late-flowering crocosmias such as 'Star of the East' and 'Emily McKenzie', a few searing pink nerines, a hydrangea or two and the bright, sparky foliage of the almost perpetual-flowering Euphorbia ceratocarpa and Cyperus eragrostis and they look exceptional.

Best forms

Aster novae-angliae 'Primrose Upward' in a bright, strong pink; the brilliant deep pink Aster novi-belgii 'Carnival'; Aster novae-angliae 'Andenken an Alma Pötschke' and the rich purples of Aster novae-angliae 'Violetta' and Aster novi-belgii 'Cliff Lewis'. For foliage, chose Aster novae-angliae 'Andenken an Alma Pötschke'.

Just say no...

Pale colours such as the white Aster n-a 'Herbstschnee', pastel A. n-a 'Miss K.E. Mash' or 'Harrington's Pink' and the pale mauve A. n-a 'Barr's Violet'

KNOW YOUR ASTERS

Novi-belgii cultivars

• Easy to grow

• Rich range of colours, including deep pinks, plums and purples

• Long flowering season

BUT

• Tendency to powdery mildew. Keeping the beds weed-free helps as the weeds act as a host to the fungus and decrease air circulation. Preventative spraying is the only sure way to avoid the problem. Keep plants well watered and divide every third year, replanting the outside sections of root in a new place.

Novae-angliae cultivars (New England asters)

• Easy to grow

• Excellent pest and disease resistance

BUT

• Tend to come in pale, pastel colours, but there are strong-coloured varieties – 'Helen Picton', 'Lachsglut' and 'Lucida'.

• Short flowering season

• Stems lose their lower leaves, so plant in the middle or back of the border to hide any baldness. Divide plants regularly in early spring.

Growing tips

• Asters thrive in fairly damp soil with plenty of organic matter added on planting, and added as a thick mulch in spring. Plant them in full sun.

• Aster amellus varieties like good drainage so add grit to their planting holes.

• Both A. amellus and frikartii varieties prefer an alkaline soil.

• Most taller varieties need support. Make this inconspicuous with hazel or silver birch supports.

Where to buy

Old Court Nurseries and Picton Garden, Colwall, Malvern, Worcs WR13 6QE (01684 540416; www.autumnmasters.co.uk) has the National Collection of asters and a huge selection for sale by mail order.