Autumn leaves

Sunday, 17 May 2009

Foliage of Pistacia chinensis

I hope everyone enjoyed yesterday's perfect Sydney autumn day. Autumn leaves are at their peak right now making our gardens and indeed our whole landscape change dramatically. Alas, in Sydney we do not experience the full foliage splendour found in areas such as the Blue Mountains or the Southern Highlands. The cooler nights and more extreme day/night temperature differences in such areas allow for the best development of the coloured leaf pigments as chlorophyll is withdrawn from the leaves of deciduous trees.

Fortunately, we can still enjoy some autumn foliage, as there are various trees and shrubs which thrive and produce a good display here to give us that sense of seasonal change. Autumn-foliage trees can become stained-glass windows when back-lit by the low-slung autumn sun as well as looking stunning against azure autumn skies or evergreen background trees. They can combine wonderfully well with some of the late flowering hot-coloured flowers such as lion's tail (Leonotis leonurus), florists' chrysanthemums and Salvia, as well as with purple and blue blooms.

Foliage of Acer palmatum

Fallen coloured leaves gathering on the ground create a satisfyingly crunchy tapestry carpet underfoot if they are not too hastily raked away by tidy husbands. Leaves collecting on outdoor tables, benches and chairs, on lawns and amongst other plants lend a transient, beautiful seasonal touch to our gardens.

Most gardens could contain one small to medium autumn-colouring tree to signify the change of season, and if such a tree can be positioned to provide shade for outdoor living in summer and sun to the same spot in winter, so much the better. The more noble and imposing autumn foliage trees, such as Liquidambar and Gingko are probably best admired in someone else's garden, or in a park or botanic garden.

Sapium sebiferum

It is best to buy a deciduous tree locally and when it is in autumn leaf to ensure it has the potential for good colouring. The Chinese tallow tree Sapium sebiferum colours reliably in Sydney and has a domed canopy (ht 8-10 m). Its heart to diamond-shaped leaves turn to glowing mosaic of scarlet, yellow, orange and lime green.*

The Chinese pistachio tree (Pistacia chinensis), growing to around 8m with a shapely rounded umbrella-like crown, also colours very well. Its green, glossy, pointed leaflets transmute into a pretty quilt of orange, yellow and scarlet, accompanied by clusters of red seed pods on the female tree which attract many parrots. The true pistachio (Pistacia vera) which can produce the edible nut, has less spectacular yellow autumn foliage.

Lagerstroemia indica

The vase-shaped canopy of the crepe myrtle tree (Lagerstroemia indica), ht 6-8m, which I have previously eulogised for its lovely summer and autumn flowers, turns its simple elliptical leaves to yellow and often orange and scarlet in May. They fall to create a carpet of bright coins around its beautiful mottled trunk. The dwarf forms are suited to smaller gardens.

Bechtel's crab-apple (Malus ioensis 'Plena', ht 6m) is a useful compact tree for autumn tints as is the Japanese maple (Acer palmatum ht 3.5-6m), which may succeed in a sheltered position in many suburbs, given sufficient moisture and good soil. It also needs to be protected from hot afternoon sun and scorching summer winds. A reasonable display of red or orange autumn tones can occur in the dainty starry leaves. The more fancy-leaved Japanese maple cultivars and other maple species certainly seem best suited to conditions in the cooler, elevated suburbs.

The Chinese persimmon Diospyros kaki (ht 5-6m) shows vibrant autumn colouring in its large glossy leaves. It may develop a rather weeping form. In very small spaces, autumn foliage colour can be found with the non-deciduous dwarf sacred bamboo (Nandina domestica 'Nana', ht 45cm) with its red, purple and gold hues, especially when grown in a tough sunny spot.

Gardeners in cooler suburbs are also fortunate in being able to grow some other desirable autumn foliage trees such as the conical-shaped Nyssa sylvatica (ht 15m); the golden elm (Ulmus glabra 'Lutescens', ht 7-10m) and the dogwood (Cornus florida, ht 6m).

When all the leaves have fallen, they make a wonderful addition to the compost heap, especially if you shred them up first.

* The Chinese tallowwood is now called Triadica sebifera. In many areas, especially warm zones, it is now classed as a noxious weed because it spreads by seed and suckers, and can invade bushland.