Gardening: A whiff where the wild things grow: Anna Pavord plans a scented walk along a woodland way, with lilac, viburnum and bushes of mock orange

IT STARTED with primroses. On the damp, heavy clay of our garden, they seed themselves into paths, vegetable patches and borders with the easy fecundity of dandelions.

But one day, when I was hop- scotching up the bank like a drunken kangaroo, bouncing over the primrose clumps that lay scattered all over the path, I decided enough was enough: the primroses could not be thrown away, but they must be moved.

Luckily, we had started a new project: a path running the whole length of the left-hand side of the top lawn. We planted a yew hedge, all of 1ft high, to offer protection on the north (lawn) side of the path, and by haunting various demolition yards, eventually collected enough old rope-edge tiles to lay along the other side.

The ground on the far side of the rope-edge tiles was spare. It used to be the place for bonfires, and we had some wild Guy Fawkes parties up there - bands of children, slippery as eels with mud, whirling through the trees with their sparklers.

Because the earth had been regularly scorched, it was one of the few patches where primroses had not taken hold, so I planted the clumps from the bank to make a border next to the rope-edge tiles. From this grew the idea of a scented walk: more plants to give more good smells when the primroses' spring season was over.

The path is almost as far from the house as you can get, and the spare ground drifts through into a small wilderness of beech and sycamore, hazel, yew and holly, carpeted underneath with ivy and ferns. I have been spreading snowdrops and bluebells there, too.

So the new planting needs to be not too gardenish: shrubs that look as though they could be part of the wild wood beyond. And pale rather than dark, for the background of evergreens would swallow up dark-toned flowers.

My first thought was philadelphus, the mock orange. There is a lot wrong with philadelphus. It has a coarse leaf and a thickety habit that not even its best friend could call graceful. Its season of interest is short. And after its brief June or July flowering, it is a busted flush. But the smell] There are few things so heady. With one draught of mock orange, you suspend judgement on its faults. Aromatherapy for free.

So which variety should it be? Philadelphus microphyllus smells richly of pineapple, but it makes a finely twigged bush no more than 4ft high. Either 'Beauclerk', which has a faint pink flush in the middle of each flower, or 'Belle Etoile' with a more pronounced purple centre would do well. 'Beauclerk' (6-8ft) is shorter than 'Belle Etoile' (8-10ft), which suits my purpose, though I prefer the latter's flower. Fate, in the guise of the local nursery, will decide.

I have also been thinking of lilies, because purple martagons grow wild farther along the path, springing unperturbed from great clumps of nettle. Unfortunately, martagons smell worse than decaying cabbage, though those who love them very much swear that the smell improves in the evening, when the flowers do their siren stuff to attract the hawk moths that pollinate them.

Not having acid soil, the number of lily species that would thrive in this semi-wild position is limited. The sealing wax-coloured L. chalcedonicum is too bright, and needs an open, sunny situation. The place I have in mind is slightly shady. L. hansonii is easy to grow and likes partial shade, but the star flowers are a brilliant yellow that would not fit in the wood.

Although they are so waxy and stiff, I can see Madonna lilies there, and the soil would be rich enough to please them. For smell, they are unparalleled. Honey. Huge pulsating vats of the stuff. This lily, L. candidum, also has the unusual habit of throwing up its whorls of leaves as soon as the flowering stem has died down in the autumn. These give you markers, so you can avoid spearing their bulbs on the end of your fork when, as always happens with me, you have forgotten where you put them.

Lilies, though, are an extra. I need to put the main pieces of furniture in place before worrying about the bibelots. If I had acid soil, this would be the perfect place to plant scented rhododendrons, perhaps 'Polar Bear', which flowers late in the summer with great trusses of white flowers, each with a greenish throat. But I have not. I must stick to things that like my limey, sticky clay.

In terms of smell, the obvious choices are lilac and viburnum. The lilac would fill the month before the mock orange. The viburnum family, fortunately, offers more choice of flowering time. Leaving aside those that flower between May and July, when the other two shrubs will be performing, you could choose one with either a winter or an early spring scent.

I do not want winter-flowering Viburnum x bodnantense in the new planting; I have it elsewhere in the garden and do not feel so mad about it to double up on its out-of- flower ugliness, as I can with the philadelphus. V. x burkwoodii is evergreen and there is enough evergreen in the wood already.

But one good variety of this species, called 'Fulbrook', has heads of white flowers opening from pink buds. The old foliage turns a purplish red colour in autumn, which would be a bonus. I think 'Fulbrook' just beats the other contender, V. juddii, which is about the same size; it is deciduous, but its flowering time is slightly later than 'Fulbrook' and might be too close to that of the lilac.

In thinking about plants for the scented walk, habit and flowering time have been uppermost in my mind. I have not been thinking about the scents themselves, or about ways of contrasting them. But how do you catch and classify the essential variations between smells that you like?

Count von Marilaun tried in 1893. He arranged flower smells into six groups, depending on the chemical predominant in their essential oils. The plants he classed as indoloids, such as skunk cabbage and cuckoo pint, smell of rotting meat. Out with the indoloids - rotting meat is not what I have in mind.

His second group he called aminoids: small, generally cream-coloured flowers that smell of ammonia and stale fish. Think of privet, pyracantha and Cotoneaster frigida. No joy there for the scented walk.

Lilac, viburnum and mock orange all belong to the same subsection of his third group, the benzoloids. In terms of contrasts, then, I am getting nowhere. I must be a benzoloid addict, for madonna lilies, jonquils, honeysuckle and lily of the valley - all favourites of mine - belong to this group.

I think I can live with that. I just wish they were not called benzoloids. It makes the walk sound like a motorway service station.

For a comprehensive survey of plants that smell good, read Roy Genders' scholarly Scented Flora of the World, just published in paperback by Robert Hale ( pounds 14.99). Its appendices suggest scented plants for a wide variety of purposes.