Gardening with Diarmuid Gavin: Autumn splendour
It's impossible not to fall in love with leaves at this time of the year, so follow my planting guide to get the best fall display
Leaves contain several pigments - chlorophyll, carotenoids and anthocyanins. The chlorophyll, which absorbs light and produces energy, is green and while in full production over the summer, masks all the other pigments in the leaves. When chlorophyll production ceases in autumn and the tree prepares for winter, the yellows and oranges of the carotenoids are now visible.
Warm days like we are experiencing coupled with some cold nights will increase sugar production and the development of the anthocyanins - pigments which are crimson, red and purple. So start planning trips to local parks, forests, arboreta and gardens to make sure you see the best of this year's display.
There are certain trees that one thinks of immediately at this time of year. American sweetgum (Liquidambar styraciflua) has maple-like leaves, but the central 'finger' is lengthened, giving the leaf a much more elegant shape. The colour changes of this species - the deepest burgundy, scarlet red and a shimmering yellow - are particularly spectacular. Most striking is the fact that the tree tends to show its colours in blocks so the hues are that much richer.
The katsura tree (Cercidiphyllum japonicum) is an excellent garden tree with tiny heart-shaped leaves that are bronze when young, developing into a rich green in summer and which eventually glow in red and yellow in the autumn. As it is slow growing, it is worth investing in a mature tree at the outset.
Persian ironwood (Parrotia persica) is better for larger gardens to allow it to achieve its full size, but the cultivar Vanessa is suitable for smaller plots as it is more upright than spreading in habit. Its leaves have attractive serrated margins starting out in a red-to-purple shade and turning a deep yellow late in the season. Its bark appears in patches of delicate pinks and beiges, making this a gorgeous garden tree. It's also a slow grower so it would be good in most garden sizes.
Great value for money is snowy mespilus (Amelanchier lamarckii). A fragrant and fine creamy-white blossom in spring is followed by apple-green oval leaves in summer, which then develop luminous autumn colours. The bare stems are covered in shiny black berries to decorate the winter. It is stunning for borders, as hedging or as a smaller pruned shrub.
For the smaller garden, a relatively ordinary looking tree, sorbus Joseph Rock, can become a star attraction at this time of the year.
Japanese maples are also perennially popular. I planted an Acer palmatum Osakazuki just a few years ago outside a bay window. It has a wonderful arched form which frames the view. And while it's pretty most of the year, now it's really heating up with its leaves turning shades of scarlet.
Shrubs are a wonderful way of introducing colour in autumn. The smoke tree (Cotinus coggyria 'Royal Purple') has deep maroon leaves on long slim stems which turn scarlet in autumn. Viburnum farreri has beautifully-shaped leaves that produce a bronze-to-purple colouration in autumn and then clusters of white flowers from November through to the following spring. Its cousin, viburnum opulus, is a real stunner with a rich yellow autumn colour and its clusters of shiny red berries. All these shrubs are available in most local nurseries and are fabulous for seasonal impact.
In autumn, individual plants, which for most of the year seem nondescript, suddenly burst forth as if burning. In my garden, the best example of this has been a much overlooked shrub, stag's horn sumach (Rhus typhina). Its strap-like leaves are screaming for attention as they turn various shades of orange, gold and yellow. This sometimes ordinary-looking plant suddenly has its time to shine.
The most common of climbing plants, Boston ivy (Parthenocisuss) can be seen adorning buildings and walls throughout the land, its brilliant tones forming mouth-watering displays. The spindle bush (Euonymus alatus) is a slightly exotic creature which acquires a coat of burning red at this time of the year.
Enjoying autumn colour is one of the last seasonal rewards of the gardener before we go into the colder, gloomier winter period. But remember, it's not just about your own garden - getting out into parks, appreciating the intense colours can be a magical experience.
'Leaf peeping', as it's called, is a tourism draw in parts of America and places like New Zealand. Indeed, on the weather channel in the US, great attention is paid to how the colours of autumnal trees are faring and what is looking good where. Isn't it magic to think that it all occurs because of little chemical changes in leaves?
This week in the garden:
Collect fallen leaves and add to the compost heap. Or just collect in bags and puncture a few holes to allow air in. Keep the lawn clear of leaves.
Along with dahlias, you need to lift gladioli corms and begonia tubers before the heavy frosts and place in a dry place. Clean off and store in trays.
Apply grease bands at the bottom of your fruit trees to prevent wingless moths from crawling up to lay their eggs.
In the veg garden, sow broad beans for an early crop next year. Spread a good layer of mulch or well-rotted manure on empty veg plots to re-nourish for next spring’s planting.