The daisy chain

September IS a great month in the garden. As the sun rolls away from the Northern hemisphere, the light grows gentler, and long slanted rays are more picturesque than the overhead brassy stare of high summer. Even when no rain falls, night dews refresh the plants. At this time of year, being outside has an added poignancy. It is the last chance before winter comes and everything goes underground until the next spring.

For those who always go away in August and come back to find a tired garden, Michaelmas daisies and chrysanthemums are just the plants to revive jaded flower beds. If you hurried out to buy some now, while they are in flower, next year you could create enough plants to greet you after the holiday. Their impact would be a refreshing consolation as the grind starts again.

Before Pope Gregory changed the calendar to make Michaelmas fall on 29 September, Michaelmas daisies were known as Starworts, or Asters, which is now their botanical name. I am unusually fond of them, maybe because of the memory of one daughter's wedding at Michaelmas. Another had a baby born on the same day last year (very suitably christened Joseph Michaelmas). Associations are a terrific bonus when choosing plants and Michaelmas daisies, especially the blue ones, are the perfect flowers for this misty, sentimental time of year. You can forget lanky mildewed stems with a few starry flowers: there are now some very good forms about which will not collapse, wilt or go white with disease. The ones to avoid are the novi-belgii. When well grown they are desirable, and in the loveliest of colours, but unless you want to be active with the fungicide from mid-summer they will disappoint you.

Not too far from London, Waterperry Gardens at Waterperry in Oxfordshire has a good collection of asters which it also sells, and it is well worth a visit right now. The National Collection of Michaelmas daisies is held at Old Court Nurseries in Colwall, near Malvern in Worcestershire. They open daily from the second week of September for a month, for the viewing of varieties and for the public to buy. In either of these places, or in your local garden centre, go armed with the determination to resist those high-maintenance novi-belgii and concentrate instead on the hybrids that have been developed from amellus, cordifolius x frikartii and lateriflorus. It is also worth sticking to novae-angliae forms, which may not be in the spirit of the times but these, unlike the Common Market novi-belgii, are not mildew prone.

Aster x frikartii `Monch' should be on offer in good garden centres. This is the one that will flower from July to October, and its thin blue petals with gold centres make lovely daisies. I usually welcome anything that flowers for months on end, but perversely I am never certain about `Monch'. July and August are off-season for asters, they seem to belong to September and October.

Aster `Little Carlow' (cordifolius) is my favourite and it is out now with soft blue single flowers in shoals. The plants are three foot tall. `Chieftain' is another good blue cordifolius, and `King George' and `Violet Queen' (amellus - the tallest of the bunch) are strong plants if you like purple. For pink you need the patriotic novii-angliae: `Harrington's Pink' for something restrained; `Alma Potschke' for a shocking cerise. These two are quite stiff growers, though, and lack the airy grace of the cordifolius forms.

One or two of the odder asters are rewarding. Aster turbinellus is covered in tiny violet stars. Aster lateriflorus `Horizontalis' is a small-scale architectural plant with stiffly held twiggy tiers of twin-stemmed purple branches bearing small pink flowers. Aster lateriflorus `Prince' is even darker. If you buy any aster now and plant it by next spring you should be able to make at least half a dozen more plants. You can divide these again if you grow them with care. Better still, you can move all this progeny at any time during the summer into their flowering positions, provided they are well watered. After October they should stay put: in winter asters like a stationary life, as their roots will not settle into cold soil.

Chrysanthemums are even more end-of-the-yearish than asters - many will wait until November to flower - and have rather grander associations. In Japan they were the emblem of the Mikado and the Emperor himself composed poems in honour of their flowers. Their official name is now Dendranthema, which somehow lacks a cheerful ring. But don't worry about that, or what you already think you know about chrysanths. Huge prize-winners or stiff flowers in pots are not at all like the hardy garden flowers. The rubellums are the first to flower outside. These look like old-fashioned single daisies in apricot and yellows. `Clara Curtis' is a good pink and `Mary Stoker' an agreeable orange. They grow in a civilised branching sort of way and are easy to fit into a flower bed. `Apollo' also branches, but more stiffly and its flowers are a stronger flame orange.

The double quilled sorts are the ones I like best, but they are less relaxed in their way of growing so they need careful siting. `Anastasia' and `Meikyo' have little button flowers not much bigger than a thumbnail and crisply curled leaves with that characteristic smell of autumn - dead leaves and bonfires and a tang in the air. Both of these are mauvy pink, but there is a white `Anastasia' which is currently only available at Cotswold Garden Flowers (which has a mail order service, ring 01386 47337). They also sell `Wedding Day', a looser growing plant, which has white flowers with a greenish centre. Latest and perhaps loveliest of all the chrysanthemums (I draw the line at writing Dendranthemas) is `Emperor of China'. Pink quilled petals and rosy bronze leaves make November worth living for.

Chrysanthemums are easy plants - a little sun and a little care and they will flower well. Like asters, they need dividing in the spring which will give you masses more. They will also move obligingly to any position in the garden to fill a gap in the summer months but, again like the Asters, they will not take to being moved in the winter. Occasionally, one or two varieties fail to make it through the cold months, but the rubellums usually survive, ensuring you a late summer treat for the following year.