The garden is beginning to wind down as the days shorten and the night-time temperatures drop.

The trick now is to keep the garden going for as long as possible so that you can enjoy the dying embers without the restless pressure to plant and sow. Personally, I welcome shorter evenings so that I can reacquaint myself with the glories of long evenings by the fire with a book.

Asters are a garden essential at this time of the year and plenty of them are only just getting into their stride. ‘Little Carlow’ is already a haze of tiny blue stars. ‘Coombe Fishacre’ is mauve-pink froth that shines in the gloaming and this one develops purple-red glints as the flowers mature. However, I’m still waiting for Aster turbinellis to erupt into an umbrella of lavender-blue to grey flowers: it usually does it here in October. These tiny-flowered asters create clouds and, even before they flower, they display narrow foliage and tiny dark buds. These are my top three autumn billowing clouds.

Waterperry Gardens, near Wheatley, are famous for their asters and their autumn borders. They are holding a Michaelmas Daisy Weekend on September 17 and 18 between 10.30am and 4pm. The gardens and plant centre are open until 5.30pm. There are tours of the garden at 11.30am, 2pm and 3.30pm, and their nursery sells a large range of asters, all raised at Waterperry. There will be a talk on the care of asters at 2.15pm each day. The Friends of Waterperry Gardens have their plant and book sale on Saturday. There’s also a special Michaelmas-themed menu in the teashop. On Sunday, the gardens are open in aid of the National Gardens Scheme and all the entrance money will be donated to nursing, caring and gardening charities chosen by the NGS.

This is an excellent time to plant pot-grown asters. But if you have asters that you want to divide in your own garden, do not do it now while they are flowering. You will probably lose them. Always divide flowers that perform after midsummer’s day in the spring. Either replant them into the ground (with a sprinkling of bonemeal to encourage root) or pot them up for September planting.

I don’t use asters in my summer rose and peony borders, however. Here I use easily grown annuals bred from a Mexican species called Cosmos bipinnatus. They get cool, evenly balanced days and nights in their homeland and therefore always shine in September as the temperatures drop. Sow seeds in March or April, prick them out into individual small pots and then plant outside in early May. Then they will flower without fail from June onwards, going on until late whatever the weather.

Good selections include the semi-double ‘Psyche White’ and the 18-in high mixture of single colours — the Sonata Series. ‘Double Click’ is an award-winning semi-double mixture of colours (All from T & M).

I had always thought that the semi-doubles were recent arrivals. However, a trawl through an old gardening book (Modern Garden Craft Volume Two, edited by Arthur J. Cobb and published in 1936) clearly shows a vase full of singles, doubles and anemone-centred cosmos arranged in a vase. This is a reminder of what a good cut flower they are.