It’s come round to the time of year when the lawn mower morphs from a tool for cutting grass, into a vacuum cleaner for fallen leaves.

Autumn seems to have pounced on us this year. I can trace it back to a day about a week and a half ago, when the air took on a chill, and the heavy dew on the grass lasted the whole day. The trees seemed to start turning in an instant response, with leaves colouring up and beginning to fall.

By then, the asters were barely into bud, but the sudden change seemed to kick them into action, and they’re now fully out and looking good. Asters are pretty much the last summer perennials to flower. When everything else is going over, their leaves are fresh and vital, their intricate daisy flowers in purples, blues, pinks and white, are pristine and vibrant – oases of shining beauty among a sea of decay. If you want to extend your garden’s flowering season into the autumn, you can’t do better than to plant some asters.(1)

Aster novi-belgii ‘Audrey’ – for the bad news, see note (1)

We typically think of autumn as a time of tidying and clearing up – clearing leaves, cutting back dead foliage and flower stems on perennials, pulling up spent bedding plants, taking out tomatoes and cleaning the greenhouse. But it’s also a busy time for more creative tasks. Now is the time to plant spring flowering bulbs, in pots and in the ground. Daffodils need to be planted as soon as possible, but most tulips can wait until November – in fact it’s best not to put them in the open ground until then, particularly if you have heavy soil. It’s a good idea to cover bulbs with wire mesh to stop rodents digging them up (easier to do with pots than for those planted directly into the ground).

Now is a good time to divide many perennials, although some people prefer to wait until the spring to do this, as there’s a danger that the reset plants could be killed by the cold weather. On the other hand, doing it now gives them a chance to establish a good root system, so they’re ready to get growing in the spring. And it’s easier to see what you’re dividing at this time of year, because by the end of the winter, perennials often don’t have much showing above ground.
Aster novi-belgii ‘Climax’ – again, see note (1)

And of course, autumn is a great time to plant roses, as well as most other shrubs, and trees. The soil is still warm (even if the weather isn’t) and reliably moist, giving them a chance to develop their root system so that, as for the perennials, they’re ready to start into growth the following spring. And woody plants can be bought bare-rooted, which is much cheaper than buying potted specimens – particularly relevant if you have a lot of plants to put in (say, for a deciduous hedge).

When it comes to the autumn clearing up, there are decisions to be made. Ideally, fallen leaves can be collected up and made into leaf mould. If you’ve got a lot of leaves, you can make a leaf mould bin by wrapping wire mesh around four wooden posts set out in a square. If you don’t have enough leaves for this, or anywhere to put it, you can fill a black plastic bag with leaves, tie it up, put a few holes in it with a garden fork, and leave it somewhere out of sight. Either way, you should have leaf mould by this time next year.

However, for some plants that are diseased, such as roses with black spot, apples with scab ,or quince with leaf blight, experts suggest collecting the leaves and burning them. The theory is that if you compost them, the spores of the disease may survive and re-infect the plant the following year. The problem comes where your leaves have blown about and intermingled – you can hardly sort them one by one!

The other decision is whether or not to cut back the dead foliage of perennials. Some people can’t bear to see them making the garden look untidy over the winter. Others think that they can look attractive, particularly when the frost is on them, or when they’re backlit by the winter sun. And they do provide homes for insect wildlife to spend the winter. Personally, I tend to wait until the spring to cut back the dead growth.
Canna Neubert, taken only a few days ago – who said the summer was over

(1) In what appears to be an ongoing scheme to make our lives difficult, botanists have recently re-classified some (but not all) asters, and given them the new name ‘Symphyotrichum’. Maybe they’re jealous of our ability to speak horticultural latin. Or perhaps they’re just trying to justify their own existence. It seems to be the later flowering novi-belgii group that have been renamed.

Words and pictures copyright Graham Wright 2017