Ode to a gnome, a pig or an urn

Placing objects so that they look their best in a garden is more difficult than, say, wandering round your sitting-room with a new picture to hang. What with windows, doors, fireplaces, built-in cupboards, sofas and suchlike, your options for wall- space are limited. In a garden, even a titchy one, you can stumble for days with your arms round the bosom of a production-line Venus, looking for the right place to put it.

But though, on their own, they cannot resolve the inherent problems of badly designed and laid-out gardens, beautiful ornaments certainly help to redeem them. They distract attention from things you do not want to look at. By setting eye-catching objects in certain places, you manipulate the way that your eye travels round your patch. A well-placed pot, seat, bust, urn, birdhouse or arch will force you to pause, while you take it in. These are the equivalent of the semi-colons and full stops that crop up like oases in deserts of poorly punctuated prose.

Whatever this object might be, it should be worth looking at. If the eye is to be drawn, it must feel it has been worth the journey. As far as I am concerned, this rules out boys peeing in pools, nymphs and nymphets, goblins (though I am very fond of gnomes), anything in white plastic and any wooden structure stained garden-centre orange. But I would defend to the death a gardener's right to have these things if they gave him or her pleasure.

Scale is important. So is line and texture. Objects in a garden are more often too small than too big. Big does not always equal expensive and, like tubes of toothpaste, the bigger you buy, the less pence per cubic inch you spend. One huge urn in a small courtyard garden can be breathtakingly good - if it is in the right place.

If you are playing games with scale, as when you put a disproportionately large object in a small space, you do not want to compound the shock by placing it in too obvious a place. So I would not think of putting a huge urn or pot or sculpture in the middle of a small courtyard garden, but towards the back, to one side, where it could be trailed over by some rambling rose escaping from a boundary wall.

If you come into your back garden from one side, as you so often do in town gardens, down a narrow passage, I would have the urn (or whatever) in the corner diagonally opposite to the point of entry. If it is directly in line with the way you arrive in the garden, your eye will go straight to it and the bulk of the garden to the side of that narrow sight-line will be cancelled out.

Objects can be asymmetrically placed in a garden and work particularly well like this if a garden is very long and thin. You can balance the bulk of a sculpture or sundial or olive jar by planting an equally bulky shrub, such as osmanthus, to balance it on the other side. You wouldn't put it opposite of course, but further down the length of the garden. In that way, your eye, instead of zooming straight to the end of the long corridor, will zigzag down the space, taking in the incidents placed to left and right.

Objects in a garden will often be set against a complex background and you will usually be looking at them from more than one angle. You must be able to "read" the line of the object against its backdrop, which is why simple shapes such as olive jars are so successful. The reverse happens in grand gardens, where complex Italian statuary reads best against cool simple backdrops of dark, clipped yew.

Texture, too, has to work hand in hand with setting. In a shady corner, where the surrounding foliage sops up light (as yew does), you could use an ornament of shiny stainless steel to great effect. In full sun, it would be blindingly unsoothing. Texture has a lot to do with overall style. Wicker, rattan, and terracotta all have a homely quality. Galvanised metal is for those who like SMEG kitchens and stainless-steel flash-backs, as my peerless mother-in-law calls them.

The aim, always, must be to include garden objects in the party rather than impose them on it. A well-placed urn or statue should be rooted into the design of the garden. A self-conscious ornament is a solecism. As well as looking comfortable, it must look inevitable. It should not look as though it has been dropped by a passing auk.

Geometric styles dictate more clearly than free-form ones where objects should go. In a garden of straight lines, ornaments can be set where paths cross, or where they end. In a design of swirls and curves, you don't want anything to disrupt the flow. Your planting perhaps will be brought out in promontories, shielding an object from view until you have rounded a corner.

Some objects, such as finely glazed ceramic jars in deep red or Rupert Spira blue, need to look fresh and crisp. Scrub them regularly to retain their gloss. But stone urns, like luggage, should never look new. If real stone is beyond your budget, buy reproductions and either bury them for a couple of months in the compost heap, or wash them with milk to encourage lichens. A bath in liquid manure is an even better way of encouraging the aged look that dealers call patina.

Not all urns are for planting. Some are for leaning on, some for writing odes to, others furnish vistas, even if the vista is only 10 yards long. Some run the risk of becoming expensive litter-bins. If you live with someone who doesn't know an urn from an ashtray, raise the urn up on an Olympian plinth, far from the sordid detritus of everyday life. Ferns planted round the base will soften the outline and stop the thing shrieking "Look at me!".

Very shallow urns or other containers should be left unplanted. Sometimes you can use them as miniature reflecting pools, filled to the brim with water. But you must fish out debris on a regular basis. When you gaze into it, you should see the sky, not rotting privet or drowning wasps.

Greyhounds are classy companions in a garden, whether in the flesh or in stone. In this case, two is twice as good as one, lying either side of some steps perhaps, or gazing moodily over the terrace. You have to live up to greyhounds though: champagne not cider, rare schisandra, not red salvia. If you feel this would be a strain, try a litter of stone piglets instead - much less demanding. The Landscape Ornament Company (01380 840533) has them for pounds 125 each.

The best decorative containers for planting are neither too deep nor too shallow. Portland stone, either real or reconstituted, ages to a pleasing greenish-grey colour, a good foil for plants. Tulips are naturals for urns, dark mahogany "Abu Hassan" or one of the shorter kaufmanniana hybrids, with striped, mottled leaves. Either of these can be whipped out by the end of May and replaced with a second display for the summer: purple heliotrope with pale antirrhinum, Fuchsia "Thalia" intertwined with nasturtiums, helichrysum intertwined with anything. The great thing is not to be in awe of your garden ornaments. They will probably have cost you too much. Make sure they earn their keep.