Turn a new leaf to stay cool

BY THIS time of summer, any summer - even one not as hot as now - shade in the garden becomes as covetable as the tulip in 17th century Holland. An umbrella or a shade sail will yield instant relief but none of the dappled light and lazy languor of trees and climbers.

Moreover, plants provide an additional cooling effect quite apart from their shade-giving qualities, thanks to transpiration. By absorbing liquid water through their roots (assuming water is there for the absorbing) and evaporating it into the atmosphere through their leaves, plants lower the temperature of the surrounding air. That's why air temperatures have been found to be cooler in spots shaded by vegetation than by umbrellas. And it's one of the reasons air temperatures are often warmer in cities compared with surrounding areas.

For respite in the home garden, the more wide-spreading the vegetation, the better. Where Banjo Paterson's jolly swagman camped under the shade of an expansive Eucalyptus coolabah, the compact size of domestic blocks puts the brakes on the sprawl of a tree most of us can plant.

If it's a massive Moreton Bay fig you want to lounge under, a public garden is the place for you. While the occasional domestic garden can accommodate the width (often 10 metres or more) of an elm tree, even the narrowest strips of inner-city yards can handle climbers grown over pergolas or other purpose-built structures.

By choosing a deciduous climber or tree you can also have winter sun, which is why the ornamental grape (Vitis vinifera) and wisteria are popular choices for spots in full sun. Other climbers useful for creating shade are the evergreen star jasmine (Trachelospermum jasminoides), Hardenbergia and Kennedia (the last with their pea-like flowers shown to great effect in the arbour garden at the Royal Botanic Gardens Cranbourne).

But those with enough space can go for trees with all their full-strength sun protection. While you can't get much denser or broader than the canopy of an English oak (Quercus robur), it can be difficult to establish in Victoria and, at more than 10 metres wide, is only for those with lashings of space.

If it is just a delicate shade you seek, a plant that will let in filtered light, there is the silk tree (Albizia julibrissin) with its fine foliage.

Alternatively, the fast-growing and tough honey locust (Gleditsia triacanthos), with its feathery leaves, provides dappled shade in a wide range of conditions. The black locust (Robinia pseudoacacia 'Frisia') casts a golden light and filtered shade (but has a propensity to sucker and is a weed in some areas of Victoria). While the fine foliage of white cedars (Melia azedarach) is increasingly seen on our streets, it can be heavily pruned to suit in the garden. Another specimen to let in only dappled light is the Jacaranda mimosifolia, with its distinctive lilac-blue flowers and which doesn't grow as large in Victoria as it does further north.

The pepper tree (Schinus molle), with its weeping habit, has traditionally made for good shade but it can spread too widely. Other trees with a pendulous look - particularly alluring in a full summer glare - are the Acacia pendula, which reaches a width of up to six metres and has a silver-grey hue, and the slightly larger Agonis flexuosa, which will tolerate coastal conditions.

For bark interest, there is the evergreen hybrid strawberry tree (Arbutus x andrachnoides), with its standout bronze-red trunk and rounded to spreading form. The olive tree (Olea europaea) can also be pruned to make more of a feature of its trunk and good shade, even for relatively small gardens.

Also for smaller gardens, the Japanese maple (Acer palmatum) will give summer shade (not to mention autumn colour) and won't get wider than about five metres. Alternatively, opt for a dwarf form of Eucalyptus leucoxylon, which will tolerate coastal conditions.

For moist conditions, the heart-shaped leaves of the linden (Tilia cordata) cast luxuriant shade (though at maturity it can be more than eight metres wide), while the common horse chestnut (Aesculus hippocastanum) will also provide good shelter where there is enough moisture and - growing to about 15 metres by 15 metres - space.

Those with an inclination towards productive gardens can use their fruit trees for shade (the less pruning, the better for this); because they are deciduous, they won't block winter sun.

The elegant persimmon (Diospyros kaki) offers good shade, as do the deeply lobed leaves of the common fig (Ficus carica).

Alternatively, the apricot (Prunus armeniaca), apple (Malus domestica) and common pear (Pyrus communis) can also make good shade trees for people with smaller gardens.

In fact, most any plant, barring perhaps the most slender of specimens, can be used for shade.

As with any plant selection, it will be a matter of assessing the site, the climate and the function and look you desire.

This story Turn a new leaf to stay cool first appeared on The Sydney Morning Herald.