GARDEN ADVICE

How to Choose Plants for Autumn Colour and Why Leaves Fall in Autumn

What can better the chilli, caramel and coffee colours of Autumn displayed by leaves determined to go out in a blaze of glory.

So what causes leaves to fall in autumn? Basically it is a sort of specific ageing process. Auxin is a plant hormone which is produced in the leaves during the growing season. In autumn auxin production reduces allowing the gas ethylene to weaken the cell walls in the leaf stalk. In addition Chlorophyll which is the green pigment essential to photosynthesis (the manufacture of food by green plants) breaks down and the leaves change colour.

For leaf colour the Acer family (the Maples) is a good place to start. Acer palmatum "Atropurpureum" (up to 20ft) is a shrub or small tree which has purple foliage which turns a vivid red in autumn. Acer japonicum is a larger subject with green foliage maturing to red in autumn. Though the leaves of Acer davidii may turn yellow or orange at this time of year it is often grown for its green and white branches. To get the best autumn colour from Acers requires neutral to acid conditions. They also prefer a lightly shaded spot away from chill winds.

Cornus kousa is a Dogwood that carries dark green leaves in summer which turn bright red or purple in autumn.

Amongst the climbers the Japanese or Boston Ivy (Parthenocissus tricuspidata) really shows off in autumn. This is a vigorous climber (up to 70ft long) not for the faint hearted but ideal for covering an awkward spot and tolerant of north and east facing aspects.

But it is not only leaves that give autumn its distinctive colours. For brightly coloured fruits different varieties of Cotoneaster will give a choice of yellow orange and red as will Pyracanthus with its spiny stems to deter burglars.

Crab apples produce lovely downy fruits which make the most delicious jelly ideal on hot buttered toast. Malus "John Downie" produces nice large crab apples for preserve making. Malus "Golden Hornet" gives a larger crop of smaller more attractive fruit but they are less suitable for making jelly.

Roses are usually grown for their flowers but many of the species roses and old fashioned varieties have the added advantage of striking hips in autumn. Rosa glauca and Rosa eglanteria (the Eglantine or sweet briar rose) are cases in point.