The colours of autumn are so evocative. Russet, ochre and translucent crimson can look magnificent against a clear blue sky – or more importantly they can light up a dull grey day, catching the eye and cheering the heart. It is fascinating to know a little about the science behind the colour change in the second half of the year, as explained by Chris Clennett at Kew: ‘Trees, like most plants, use chlorophyll to photosynthesise…In autumn, trees that lose their leaves for winter go through a process to shut down photosynthesis and reclaim as many valuable chemicals as possible. Chlorophyll is constantly breaking down and being replaced through the summer, but the process slows down in autumn. This reveals all those other chemicals that were hidden by the presence of the dominant green chlorophyll…yellow flavonols, orange carotenoids and red to purple anthocyanins.’
Parrotia persica
Michel VIARD
In the garden, trees play the biggest part in the autumnal fanfare, so it is important to choose at least one or two that give you what you need at this time of year. Classic, fiery autumn colour comes in the shape of trees such as Parrotia persica, the ironwood tree (eventually growing to 10m), which turns beautiful shades of orange and yellow in autumn. The cultivar P. parrotia ‘Felicie’ is particularly worth looking out for, as its leaves turn vivid shades of crimson, lighting up like stained glass when the light shines through the leaves.
For smaller gardens, it makes sense to plant a tree that also gives value at other times of year so you are maximizing the space, and one of the most rewarding small trees is Amelanchier lamarkii (4-6m) which offers early spring blossom as well as good colour in autumn. Beth Chatto voted it her favourite small tree or shrub, declaring: ‘Good form in winter, lovely foliage in spring and autumn, prettier than many cherries – and interesting for longer.’ Another excellent all-rounder for a small garden is Cornus kousa ‘Miss Satomi’, which offers ornamental pink bracts in June, followed by rosy-pink fruits and stunning autumn foliage. Many of the Japanese acers (Acer palmatum) are similarly rewarding in both spring and autumn. Two of my favourites are ‘Sango-kaku’ and ‘Osakazuki’, both displaying superb autumn colour. ‘Sango-kaku’(6m) has deep pink young stems and striking yellow and orange autumn foliage, while ‘Osakazuki’ (4m) is perhaps the most outstanding form for autumn, with intensely coloured crimson foliage.
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