Admittedly I began to use rocks in my garden because we had a lot of them. The only reason we could afford to buy this place was because it was either rock, vertical, eroded or covered in blackberry, and sometimes all four. The blackberry has pretty much been vanquished now, but there is still a heck of a lot of rocks.

I also love stones. A large boulder, perfectly suited to the terrain, seems to bring a garden together as long as it sits naturally (i.e. don't try to make a long flat rock stand up like Stonehenge - the Stonehenge builders had the genius to make each rock looks like it belongs just there). Call up multiple pics of Japanese gardens at this point, and you'll see what I mean.

Now head to walled gardens in England which, as well as being beautiful, block the freezing wind, and reflect and retain heat. In the days before refrigeration, heated glasshouses and walled gardens used to be the only way the English could taste an apricot or peach or get a decent crop of tomatoes, unless they went in for manure heated garden beds, which are not something you want in your suburban backyard. Neither do your neighbours.

I learned to build stone walls from books. If I can do it, so can you - I flunked colouring in at kindergarten. But these days the stone walls we are still slowly accumulating are Gabion walls - a mesh framework into which you either throw rocks, for a rough wall effect, or carefully put the flat side of the rock outwards for a neat stone wall effect. The advantage of Gabion walls is that you need no skill at all, and also they aren't waterproof. Concreted retaining walls collapse as water pressure builds up behind them. "Rough" stone walls let the water seep away, as do Gabion walls.

Want to grow coffee, sweet potatoes, bananas and early tomatoes in Canberra? Create a sunny courtyard. The thicker and sunnier the walls, the better. We use rocks for paving and for steps, as well as a giant boulder for a garden table and others rocks as (admittedly cold and hard) seats. I'd build a meandering rocky creek through our garden, minus water, except we already have a naturally occurring rocky creek, which does have water a fair bit of the time.

I have also fallen in love with rock mulch, the ornamental kind you buy at garden centres - white or black or blueish grey. It makes an excellent mulch for pots and hanging baskets, preferably hung or placed over paving so no fallen stones get flung up by the lawnmower, or, better yet, used as mulch on indoor plants. Stone mulch keeps in moisture, helps stop potting mix turning to concrete and just basically looks beautiful.

The heat retaining/reflecting properties of rock can be a problem in summer. But rocks walls, paving, rock steps and the like can also be turned into garden airconditioning. Place a pergola above, cover it in deciduous grapes, kiwifruit, hops, rambling roses and clematis then add - and this is key - an inconspicuous dripper system over the top of the pergola. This way, when you turn it on in the late summer afternoon, the drip, drip, drip of water evaporates and turns your rocks into a kind of refrigeration unit. The air around your house cools, and even more if there is a slight breeze to hurry up the evaporation and take the humid air away from the house.

There are also tunnel systems that use evaporation to cool homes, as well as keeping intensive pig and chook sheds almost liveable (praising this passive cooling system in no way implies acceptance of intensive chook or pig farming).

Which brings us to (whispers) fake rocks. Most of them look, well, fake. But having clambered over a hotel garden to see if their ultra-perfect-looking rocks were real or not - and it still took some fingering to decide they had been manufactured by humans not volcanoes and the weather - some fakes are indistinguishable from the real thing, even when you have your glasses on. At least they are when they're well placed within a garden. And they are heck of a lot lighter than granite.