Sunday, May 23, 2010

Autumn foliage

This is surely one of the interesting times of the year, with a plethora of wonderfully coloured trees and shrubs to look for in the streetscape. I wonder how long this will last however, as the heyday of planting deciduous trees seems to have long gone, and as more and more gardeners plant almost only evergreens, we are going to miss out on such a grand autumn display.

One of the reasons for the diminished use of deciduous trees and shrubs is surely the more diminutive gardens we now have. We simple do not have the space for the same number of large specimens and are more reliant on smaller plants for the garden.

Some plants that will fit easily into most gardens, and can be reliably called upon for a spectacular display are the various members of the Cotinus family. These are the Smoke Bushes and feature some of the most amazingly lurid colours in the autumn palette.

There are three species of these in the wild, but there are only two that are commonly available. The first of these is the European smoke bush, C. coggygria which actually grows from Europe into central China, and is perhaps best known for the large panicles of fuzzy looking plumes in early summer that give the plant its common name, especially as they grey into the autumn.

The leaves are bright green during the bulk of the growing season, but as they autumn approaches they take on the most startling array of colours, from yellow to orange to fiery red. They appear to differ from plant to plant, suggesting the New Zealand forms have been seed raised, as overseas, varieties can be selected for a particular colour.

The exception to this rule is the strongly coloured ‘Royal Purple’ which has deep wine-purple leaves which have a conspicuous waxy surface that appears translucent in sunlight. The flowers are a slightly deeper colour through the growing season, and then turn bright orange and burning red in autumn. This is a great plant for associating with lighter coloured foliage. At slightly more than two metres high it is about two thirds the height of its plainer cousin.

The American species C. obovatus is a taller beast altogether, growing to perhaps five metres. It does not have the same floral display of its European kin, but makes up for that with a stunning foliage display in the autumn, when the leaves turn yellow, orange, red, purple – often all at the same time – to give an very impressive show.

In the very small garden, there is another little treasure that can be relied upon to give a great display in autumn – and it is not even deciduous. The dwarf heavenly bamboo (do not worry it is not actually a bamboo, so it will not go mad in the garden) Nandina domestica ‘Pygmaea’ was planted extensively during the 1970s craze for pebble gardens, and has perhaps not regained its proper place in the garden, but its fresh lime leaves during the summer always look attractive, and in autumn and winter it turns on a very impressive display of purple, orange and (more usually) bright red foliage. The colder the winter, and the poorer your soil, the better this will colour up. In fact, you could even do the old nurseryman’s trick of feeding it a bit of sulphate of potash at this time of the year – it will certainly colour up better then!

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