It will be interesting to see how good the autumn colour is this year. Good, strong, autumn hues, in trees such as ‘Japanese Maples’ (Acer) and Liquidambar, rely on there being a decent cocktail of the products of photosynthesis within the leaves that are due to be shed. The disappointingly dull and wet weather, in the latter part of the summer, will have diluted these colour giving constituents but, hopefully, the burst of sunny weather, with correspondingly high temperatures, at the beginning of last month will have boosted the photosynthesising potential of the foliage. Some deciduous trees and shrubs will begin to ‘colour up’ this month although, unless it gets very cold, very quickly, they should hold onto their leaves for a while longer yet.
As usual, the tasks that need doing in the garden this month will depend very much upon what the weather is doing. When it’s dry enough to be getting onto border soil, without compacting it too much, gently remove collapsed foliage to ‘edit’ out anything that’s beginning to detract from the plants that are still holding their own. The ‘stars’ of the autumn garden, ‘Asters’ (now mostly reclassified as Symphyotrichum), deserve to be freed of any neighbouring plants which have collapsed around, or onto, them.
Many asters really benefit from being grown through a support, such as pea-sticks, inserted while the plants are still small, because it’s pretty difficult to try and prop them up now as you are likely to do more harm than good. If grown amongst a supporting cast of grasses, maybe one of the smaller Miscanthus such as ‘Starlight’ (introduced by Dorset’s own ‘Knoll Gardens’—an authority on grasses for the garden), any threatened collapse can be contained.
The various ornamental grasses, that have become increasingly available over the past few decades, not just Miscanthus, are an important constituent of the autumn garden as it dissolves into winter. It might be too early yet for decent frosts, although preparing for them now is a good idea, but the flower and seed heads on plants, such as tall grasses, look particularly fine with a frost on them so are worth leaving in situ well into next spring.
Some things cannot be left in situ until next spring; anything that is not reliably hardy, or is definitely on the ‘tender’ side, should be prepared to be brought back under cover (a frost-free greenhouse or other protected growing space). If the specimens are planted in the garden soil, such as geraniums (Pelargonium) used as bedding plants, then it’s a good idea to pot them up to allow them to establish before really cold weather stops all growth. Tender plants grown in pots and containers should be tidied up as much as possible this month in readiness for bringing under protection as soon as frosts are forecast.
Dahlias have had a huge resurgence in popularity over the past few years. They will still be flowering this month, as long as they’ve been regularly fed and dead-headed, and it is traditional to leave them outside until they are blackened by the first frosts. Thinking ahead, it may be a good idea to sort out somewhere to keep the lifted tubers over winter because they take up quite a lot of room. In sheltered spots, and in a mild winter, it may be possible to leave them in the ground, preferably covered with a deep layer of mulch, although I find that the winter wet may cause them to rot and they are a martyr to being destroyed by black keeled slugs (the sort that inhabit the soil and do their damage largely unseen).
While assessing the border it’s worth remembering that many of the high summer flowering herbaceous perennials, which have now stopped flowering, can be cut down to their basal rosettes, dug up, divided into smaller sections and replanted while the soil still retains some of its summer warmth. A lot of plants establish better, and get a good head start, if bought and planted at this time of year rather than in the spring. Lifting and dividing your own herbaceous perennials is a good habit to get into. You can rejuvenate existing border plants and also use any spare divisions to repopulate other areas of your own garden, pot up to fill future gaps or keep on hand to swap, or donate, to fellow gardeners.
Some suitable specimens include the herbaceous geraniums, day-lilies, phlox, clump-forming irises, Alchemilla (‘Lady’s Mantle’) and Leucanthemum (‘Shasta Daisies’). I realise that some plants are ‘frowned upon’, by more serious gardeners, simply because they are so easy, ubiquitous, but it’s hard to imagine a garden without a backbone of perennials such as Geranium ‘Orion’, Nepeta (cat mint) or good old Alchemilla mollis. Having a palette of dependable plants, shrubs as well as herbaceous perennials, is essential before adding the more exotic specimens to the mix—no point in running before you can walk.
As far as basic gardening tasks are concerned this month, continuing with hedge cutting, if not yet completed, is a good idea whenever the foliage is not soaking wet. Also cutting the lawn, raising the cutting height as temperatures drop and growth slows down, and generally clearing up leaves as they begin to fall. When there are only a few leaves on the lawn, assuming they are not big leathery magnolia leaves, then collecting them using the lawnmower, if it has a collecting box, is time saving. If you have a lawn bordered by generous flower borders then a certain amount of leaf fall can be dealt with by blowing the leaves, with a leaf blower, into the borders where they can rot down. Shallow borders, or borders filled with Mediterranean style shrubs, especially lavender, will not welcome a covering of soggy leaves so, in this case, raking them up is preferable.
While you are attending to all the above it’s also worth remembering that bulb planting, for spring colour, should be continuing apace. If you ordered them in a timely fashion, from an online supplier, then they should have been delivered by now and need planting as soon after delivery as possible—with the usual exception of tulip bulbs which should be unpacked but can wait until next month to be planted.
Don’t forget that, for instant bulb gratification, garden centres and many supermarkets stock a selection of the most common bulb types if you didn’t get around to ordering them from a specialist. I still enjoy the more tactile experience of selecting bulbs, from a loose display, in a garden centre such as ‘Groves’. This has the advantage that you can choose the plumpest, most promising looking, specimens as long as you get there while they still have a decent amount of stock—I tend to leave these things too late!
