The scent that was lost, and is found: Many flowers are so highly bred that they have lost their natural smell. Anna Pavord celebrates the new, perfumed sweet peas

ONE SNIFF of water mint carries me straight back to the valleys between the Rholben, the Deri and the Llanwenarth Breast in Monmouthshire, where I was born and brought up. I remember the poachers who taught us how to tickle trout in the streams, and the long afternoons we spent hanging over the banks, hair streaming in the water with the brook weed, stroking the cool underbellies of the speckled brown fish.

If you were careful and patient enough, you could lull a trout into a glazed trance. Then you had to work your thumb up its flank and slowly, slowly, over the ridge of its back. Finally, with lightning speed, you tightened your grip and whipped it out on to the bank. The tension of that last, galvanic heist still makes my heart thump. Mixed with it all is the sharp, tangy scent of the mint bruised underfoot and the complex, animated smell of the stream in my hair.

Scent is one of the most dangerously evocative of the senses. In the garden, it creates a fourth dimension - a separate, unseen landscape hanging in the air, changing shape with the seasons.

Plant breeders, whether of roses, philadelphus, pinks, heliotrope, tobacco flowers, violas or sweet peas, have underestimated the value, the potency of scent. Too often it has been sacrificed in pursuit of other objectives: bigger flowers, a wider range of colours. This is partly because of the complex nature of the scent gene, which is often linked to a more undesirable characteristic that breeders want to get rid of. Once it has gone, it is difficult to isolate and reintroduce into the pudding mix.

The loss of natural scent in flowers too highly bred for our own good is neatly paralleled by the rise of aromatherapy. Smells are good for us, chants a beady-eyed band of aromatherapists. We always knew that. The difference is that, rather than obtaining them freely from our flowers, we are now encouraged to lash out pounds 5 for a chemically prepared equivalent of the real thing. Contrariness rules, but not OK.

Fortunately, a few breeders are beginning to backtrack on the matter of scent. The name of Unwins, the seed merchants, has long been associated with the sweet pea and the company has been responsible, since the beginning of this century, for introducing hundreds of new varieties.

Novelty has always been an important factor in the world of sweet peas, but Unwins has now sensibly decided that scent is to be the hallmark of all future introductions. Size, colour and conformation of petals will no longer be sufficient in a sweet pea fighting for its place in the Lathyrus Hall of Fame.

The benchmark is a variety called 'Old Times' (Unwins 79p), a Spencer type of sweet pea with the lush, rich perfume generally found only in the older grandiflora types. It is cream, gently flushed with blue round the edges. If future new varieties fall markedly below the standard set by this one, Unwins will have to go back to the trial ground.

The grandifloras still probably have the edge in the matter of perfume. Compare 'Old Times' with Unwins Old Fashioned Mixed (99p), a collection of old Grandiflora varieties. For the better smell, you sacrifice flower size. Among the Spencers, the blue and lavender/mauve colours seem to carry the scent gene more strongly than the cerise and orange types. Try the soft blue variety 'Evensong' (79p) or the outstanding 'Charlie's Angel', named not after the defunct television programme but after Charlie Hamner of Yorkshire, who raised it.

The naming of sweet peas is far from satisfactory. Once television stars predominated, but this craze seems to be declining. Only 'Terry Wogan', a salmon pink snip at 89p, lurks on in the schedules.

Here as everywhere, attention centres on the Royal Family. Unwins' best-selling sweet pea for the past four years has been 'Royal Wedding' (99p). As yet there is no 'Royal Divorce'. 'Royal Wedding' is extremely vigorous, naturally long-stemmed, and has large well-formed flowers of the purest white. It even smells. Then there is 'Queen Mother' ( pounds 1.25), resplendent in soft salmon overlaid with orange; and 'Her Majesty' ( pounds 1.85), a new variety this year - rich ruby rose but not particularly generous on the nose front.

You can find a mid-lavender 'Royal Baby' (89p) which, though real-life experience tells you otherwise, is sweetly scented, and a glowing orange-salmon 'Diana' (99p), fortunately bred to withstand stormy conditions.

For a flower that is so much in demand - Unwins alone sells 30 million seeds a year - the sweet pea had a slow start. The original species, Lathyrus odoratus, arrived in England at the very beginning of the 18th century, sent by Franciscus Cupani, a Sicilian friar, to the staunch horticulturist Dr Robert Uvedale, master of the grammar school in Enfield.

Progress in breeding from this species was slow. The flowers were bicoloured, reddish blue and deep violet, and smelt more strongly than aromatherapists dare dream of. The plant was on sale in nurseries 25 years later, but there were only five distinct varieties by the close of the 18th century, six by the middle of the 19th.

Serious breeding began towards the end of the Victorian era, when Henry Eckford selected and crossbred different strains to produce sweet peas in more colours and with larger flowers than ever before. These were christened Grandiflora sweet peas and they still kept the swoony scent of Father Cupani's original. The first dwarf sweet pea, 'Cupid', appeared at around the same time and was exhibited at the Crystal Palace in 1897.

The modern race of sweet peas, the Spencers, have all been bred from a chance discovery in Earl Spencer's gardens in Northamptonshire. His head gardener, Silas Cole, discovered just one stem in his rows which bore flowers with more frilly petals than the rest. He saved the seed, sowed it - and with the resulting variety, 'Lady Spencer', wiped out all Eckford's work.

The best sweet peas come from seed that is sown now (although in the coldest parts of the country it pays to wait until January). Do not soak the seeds before sowing: recent research suggests that this does more harm than good and puts them under unnecessary stress.

Chipping the seed is useful, but not essential. If you do it at all, concentrate on blue and maroon varieties, which are more hard-seeded than other types. Aim for a point opposite the eye of the seed and either nick the seed coat with a sharp knife or rub it with a file or coarse sandpaper. I have never done either and have nothing to complain of in the germination stakes.

Cream and orange varieties have noticeably softer seed coats than the norm. This makes them more likely to suffer in conditions that are too cold or too damp. Use a fast-draining compost for these and keep them on the dry side. A seed dressing containing Gamma HCH is also a sensible precaution, particularly with susceptible varieties such as the creamy amber 'Charles Unwin' (99p).

Do not mollycoddle sweet peas at any stage of their lives. They need to grow hard. If you want to grow plants singly up canes, cordon style, sow seeds singly in tubes of compost - the insides of lavatory paper rolls are ideal. If your sights are set lower, plant five seeds in a 5in pot (clay ones drain better than plastic), cover them with wire netting against mice and germinate them in a closed cold frame.

When they have germinated, open the cold frame and leave the seedlings to grow on gently through the winter. They will need covering only in the harshest of weather. Set mousetraps around them. Pinch out the tops of the plants when they are about 4in high. Plant them out in April - the whole pot together, if you are not trying to get exhibition size blooms - and support them with netting, brushwood or canes.

You can succeed just as well without a cold frame. Cover the planted seeds with panes of glass or clingfilm and when they have germinated set the pots outside on a gravel bed. They will probably need a wire-netting cage to protect them from mice and over-inquisitive blackbirds. Pinch them out and plant them as described above.

There is one other thing that needs seeing to now: the trench. Sweet peas, for all their dowagery pink and mauve looks, have appetites like Sumo wrestlers. They need muck. Dig plenty in under the place where you are going to grow them. They will also make a good job of recycling the mice from your mousetraps: from rodent to 'Rosalind' (Unwins pounds 1.45).

For a copy of the Unwins catalogue, which lists almost 60 varieties of sweet pea, contact the company at Histon, Cambridgeshire CB4 4ZZ, tel 0945 588522.

Enthusiasts should join the Sweet Pea Society, whose secretary is J R F Bishop, 3 Chalk Farm Road, Stokenchurch, High Wycombe, Buckinghamshire HP14 3TB, tel 0494 482153.