One of the most spectacular moments of the gardening calendar has to be the arrival of the Autumn colour. The horizon that was once verdant and lush starts to reveal a natural tapestry of colour, hidden until now.
The leaves were once packed with chlorophyll. This green pigment has been perfectly engineered to absorb energy from the sun and turn it into carbohydrates through the summer. A combination of the shorter days, and dropping temperatures signals to the tree the imminent approach of winter. Deciduous trees have adopted the survival strategy of winter dormancy. This means that like the gardener, the tree must now shift from producing, to storing. The production of chlorophyll in the leaf is reduced and the green colour slowly starts to ebb away, revealing the kaleidoscope of pigments hidden beneath.
The colours that we see in the leaves are due to a range of chemicals present in the leaves. Carotenoids are the group of chemicals responsible for the yellow brown and orange colours. The red and purple hues come from a group of chemicals called anthrocyanins. These are both involved in protecting the leaves. They act like suncream, protecting the leaves from damage caused by the UV radiation of the sun. They can give the leaves a bitter taste, making them unpalatable to insects, and act like wood preservatives, preventing fungus and moulds from destroying the leaves.
In the US it has become an annual obsession to visit the forests of New England to watch the colours as they start to develop. This pilgrimage to the woods has become know as ‘leaf peeping’ and the effect it has on tourism in the region has been estimated to be worth around 3 billion US dollars to the economy. It is not just the Americans who have made a hobby of visiting the woods. In Japan the habit of forest bathing, or shirin-yoku, is very popular. It is encouraged to spend time in mindful contemplation in the forest to experience the natural effect of stress reduction and relaxation it induces. The trees also give off volatile essential oils such as a-pinene and limonene that are thought to be anti-microbial and great for health. This desire to be in the great outdoors has sometimes been termed as biophillia, a love of live or living systems. It was made well-known by Ernest.O.Wilson in his 1984 book of the same name where he described ‘the connections that human beings subconsciously seek with the rest of life’, and how these connections are fundamental to our sense of well-being.
If you are looking to add colour to your garden in autumn there is a huge range of plants that take on vibrant colours at this time of year. The Spindle bush, euonymous alatus has to have some of the most dramatic colour and will often turn a vibrant hue of pink in the autumn. One of my own personal favourites for colour are the Japanese maples or acer palmatum. These small trees are ideal for domestic gardens, they appreciate a rich, moist soil and a bit of shelter. The variety ‘sengo-kaku’ has incredible colour, both when the leaves first emerge in spring, and when they start to fall in the autumn. For orange and copper tones I would choose a bush like the Saskatoon, or amelanchier lamarkii, which also has fantastic blooms in spring and tasty berries in summer or witch hazel, hamamelis which will fill the garden with scent on sunny winter days. If you are looking for yellows, one of the most stunning has to be the Maidenhair tree, or ginkgo biloba. Members of the dogwood family, or cornus, will often take on a mix of deep purple or red colours as they begin senescence. One of the most stunning trees for Autumn colour has to be liquidambar styraciflua. They are often too large for smaller gardens but as the season progresses they will start to show a huge range of colours right across the spectrum. If you are pushed for space in the borders, then Boston Ivy or parthenocissus tricuspidata will quickly cover a wall and provides one of the most stunning displays as they turn from green to flame-red.
Whilst autumn is a season that sees the end of the growing part of the year, it is a season that ends with the most incredible crescendo. If you brave the changeable weather and make time to take it in, bathing in its beauty, it will reward you tenfold.