Hot tips on how to keep your cool this summer

Step one. Acquire a time machine - my choice would be a Tardis, but any brand will do, and go back 10-20 years. Settle yourself comfortably around the turn of the millennium, and plant drought- and heat-hardy trees with thick canopies around you house, enough to shade every window.

Yours trees will need to be tall enough to shade at least your walls, and preferably shade much of your roof too. Some of the best choices in our climate would be apples, pears, the taller varieties of plums or the fast-growing native white cedar, with its delicate mauve summer flowers.

Beware though - most common garden trees are now sold in dwarf or semi dwarf form, and won't be tall enough to give enough shade. The apple trees I planted 30 years ago grew fairly quickly to roof height. The varieties I've planted in the last decade have reached half way up the wall then stopped growing upwards. You may need to buy "full size" trees at a specialist nursery, or at least check the label of any tree you plan to buy to see how tall they'll grow.

Make sure they're deciduous trees, too. These will generously drop their leaves for you in a colourful display in autumn, leaving you lots of lovely material for mulch come spring, as well as a mess to clean up over winter. The lack of foliage will allow sunlight to penetrate in winter's cold to warm your walls, floors and garden.

Sadly, many of the densest and most effective shade trees - like magnolia grandiflora, bay trees, pittosporum, and avocados - keep their leaves all year, as do common hedges like box, camellias, rhododendron or fast-growing photinia. But as well as giving shade in summer, these may still be useful to insulate walls without windows in winter when the freezing winds blow from the mountains.

If by some chance you don't have access to a time machine, make a note to buy some deciduous coolers next autumn, and feed and water them well. They'll begin to make a real difference to your household climate after only five years or so.

If you already have excellent green trees and shrubbery around your home, this may be the time for summer pruning. Very dense foliage can make the garden humid, which means it's harder for your perspiration to evaporate and cool you down. It will also block those breezes, plus dense shade can be boring.

Carefully removing a branch or branches will give you vistas without affecting the heat protection, and allow breezes through too.

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You can also make use of hot walls or baking paving to cool your house and garden - the hotter the better. Just add water - lots of water, preferably a spray that will wet you and the kids too.

The water will evaporate when it hits the hot walls or paving, using energy, from its surroundings. As the heat energy evaporates, the surroundings cool.

Various affluent urban areas in Europe are already using the "water twice a day" trick. The optimal wetting seems to 10 minutes in the morning, and a longer watering, about 30 minutes, in the afternoon. This assumes that all areas will lose the same amount of heat for the same amount of water and duration of water. This is unlikely, but it's a good starting point. The cooling affect is highest just after watering, but can still have some effect up to 24 hours later.

Evaporation from fountains can also cool your garden. This is an excellent excuse to ask Santa for a fountain this year, or even two or three. Grand Mediterranean garden styles usually included long shallow ponds sited where a breeze would blow over them, leaving the air cooler and water scented. Canberra's swimming pool safety laws would need to be applied here.

Avoid artificial turf if you want a cooler garden and planet. A moist, short green lawn helps cool down your house. Artificial turf stops soil moisture evaporating, heats up and stays hot for hours, and smells of plastic. The world has enough pollution without swapping real grass for fake stuff.

The most time-honoured way to cool a home is to open it up at night to let the cool air in. Give yourself an incentive to open the doors and windows - screened to keep out mosquitoes and burglars - with the kind of perfumed plants below the windows that give out most of their scent in the evening.

One of the best of these, night-scented jasmine, can become a weed unless kept regularly in check. Try night-scented tobacco instead - a fast grower, with gorgeous trumpet blooms. It can be annual or biennial, but reseeds readily - sometimes far too readily so it too can become a weed.

Night-scented stock (Matthiola longipetala) is said to be delicately perfumed after dark, but I've never tried it. One of my absolute favourite scented plants, dianthus, just happens to be especially fragrant at night. It's low growing, hardy, and beautifully perfumed. Sadly, wallabies love it too and eat just about every flower bud. Luckily I love the scent of grass and gum trees, too.

Plant wisely and your house will be cooler, more lovely, and smell totally delightful.