Autumn is sometimes an under-appreciated season in the garden, but by including a range of suitable plants, displays of spectacular foliage colour can easily be achieved
Enjoying autumn colour
Autumn produces some of the most vibrant colours of the gardening year. An understanding of the processes that cause these colours, and knowledge of the plants that perform best at this time, helps gardeners make the most of this exciting season.
What causes the colours?
Deciduous trees and shrubs drop leaves in autumn by a process known as senescence. Underlying pigments in the leaf are masked for most of the year by the green pigment chlorophyll. As this starts to break down,
other pigments show through: carotenoids to give yellows and oranges, and anthocyanins for reds, blues and purples.
High light intensities cause sugars to accumulate in leaves, leading to more anthocyanins. Therefore relentlessly overcast weather and shady areas will not make for foliage that colours-up well. Consistently higher temperatures than normal are also detrimental, so the ideal conditions for autumn colour are sunny days followed by crisp, cold nights.
Plants with good autumnal tints
Parentage and geographical origin (provenance) are also critical factors. Trees selected from areas recognised for fine autumn colour continue to show exceptional tints when grown elsewhere. Genetic selection of well-coloured seedlings also broadens the range of these plants available to gardeners. By propagating such selections from cuttings (vegetatively) the colourful characteristics are retained. A good example is Nyssa sylvatica ‘Wisley Bonfire’ (right); plants with this name should be clones of the original growing at RHS Garden Wisley, Surrey.
Foolproof planting suggestions
There are many suitable plants to choose, most of which will colour-up well every year. Climbers Parthenocissus tricuspidata and Vitis coignetiae will scale a stout fence or house wall to create a block of fiery autumn colour. When choosing trees remember to pick one that will not outgrow its alloted space. Only a large garden is suited to Nyssa sylvatica, Parrotia persica or spectacular Liquidambar styraciflua (left), but on smaller plots try Amelanchier lamarckii, various Prunus, such as P. sargentii (right), or Sorbus ‘Joseph Rock’.
There are many shrubs with exciting autumn tints, including fiery Euonymus alatus and Acer palmatum ‘Osakazuki’, butter-yellow Hamamelis and the glowing yellows, oranges and reds of Cotinus coggygria, Berberis thunbergii and Enkianthus campanulatus.
Highly recommended Cercidiphyllum japonicum has multicoloured autumn leaves with a delicious toffee smell; Cornus kousa var. chinensis has a display starting in early summer with creamy-pink flowers, followed by red, strawberry-like fruits leading to a finale of crimson-purple autumn foliage.
Helen Bostock