Autumn colour

The autumn winds have been rustling through the garden and feeding the embers. Glimpses of red, orange and yellow are sparking into life across the landscape and also in  some of my potted shrubs that haven’t been watered quite as regularly as they would have liked and have decided to call it a day early (sorry Oak-leaved Hydrangea). Field maple and birch are turning yellow, wild cherries orange and spindle bush and dogwoods are taking on rich dark red hues. When all mixed together, and with every shade in between represented, the result is spectacular.

I have always perceived yellow to be the poorer relation of red and orange at this time of year. Not quite the real deal that we hope for when talking about spectacular autumn colour. Somehow it seems that yellow is just part of the natural sequence of decay from green to brown. Things are on the slide and yellow just happens to be on the way. Red and orange on the other hand are a display of resistance, an eye-catching display that demands attention. To give yellow some credit it does add extra vitality and contrast to the hotter colours but they don’t need it as much as it needs them.

Some quick research has interestingly shown that there are in fact different processes at work. The colour pigment that makes leaves yellow in autumn is always present but just masked by green chlorophyll. When the plant decides to start shutting up shop for the winter the chlorophyll is broken down to reveal the yellow.       

By contrast, red pigment is specifically produced by trees and shrubs in the autumn. And the reason for this is not entirely understood. It may have something to do with attracting birds to help distribute seeds or be a warning to discourage insects from overwintering on those plants. Another strong theory suggests that foliage is reddest when autumns are sunniest and that the red pigment is produced to protect leaves from the harmful effects of UV light and thereby prolong the time the tree has to re-absorb their nutrients.

Whatever the chemistry, autumn colour in the garden should be thought of as just as important as flowers. After all, the show can last for many weeks. Elsewhere chemistry is also busy adding warmth to fruits and flowers. The long-flowering fuchsia and salvia just keep on going, sedums and persicaria throwing their bold shapes and even the roses are managing a curtain call. The apples and tomatoes are looking bright, succulent in need of harvesting and it won’t be long before the chillies add some heat to an autumnal curry.