Gardens: Scents & sensibility

It's awful not being able to smell flowers. Scent is an important pleasure in a garden, hovering unseen in the air, guiding you through your plot so that even if you've got your eyes tight shut, you know you must be by your mock orange, or your climbing rose. But one of the long-lingering side effects of the flu that attacked so many people, including myself, earlier this year has been sinusitis, a dreary business as it takes away the sense of smell. And taste. So here I am, imagining all those luscious smells I am missing, hoping the real thing will come back soon.

Scent is a difficult thing to describe and leaves you floundering dangerously close to Pseuds Corner. It's so much easier to describe the way a plant looks than the way it smells. You can describe one smell in terms of another – say, perhaps, that Clematis rehderiana smells of cowslips. But to the increasing hordes of people who have never clapped eyes, let alone noses, on a cowslip, this isn't very helpful.

Sweet, heavy, spicy, sickly are the words we most often use to describe a smell. Sweet is the most over-used term of all. There is a world of difference between the rich sweetness of mock orange (Philadelphus 'Avalanche' and 'Sybille' are both particularly good) and the heavy, almost overpowering sweetness of the climbing hydrangea, H. petiolaris. Nobody ever tells you about this hydrangea's smell but it is incredibly strong at the moment with all the scent of course coming from the tiny, nondescript flowers in the centre of each head, not from the more showy but sterile bracts around them.

You are told, too, that the honeysuckle Lonicera tellmanniana would be a wonderful climber if only it were scented. But it is, perhaps not so swooningly as the native hedgerow honeysuckles, but memorable just the same. In the morning, not even the most questing, expensively insured nose will find anything there, but by teatime it's beginning to rev up and by dusk it is in full swing. Honeysuckles depend on night-flying moths for pollination. They are the only creatures with tongues long enough to reach down the honeysuckle's tube to the nectar at the bottom. During the day, L. tellmanniana has no need to turn on its come-hither act.

Many of the most heavily scented flowers are white. Think of mock orange, summer jasmine, madonna lilies, gardenia, lily of the valley, Trachelospermum jasminoides, choisya, Nicotiana sylvestris. It's almost as if they have intensified their smell to compensate for the lack of colour. Blue flowers have least smell: ceanothus, forget-me-not, delphinium, campanula, agapanthus. The exception is the bluebell with its rich, spicy smell. One of the most memorable moments of May is fixed for me in the bluebell wood at Coton Manor, Northamptonshire where waves of scent billowed over my perch as I watched the trees trace shadows over the flowers. But for the most part, blue flowers are pollinated by bees and they, like us, work more by sight than smell.

The Victorians, so keen on sorting and ordering, made a brave attempt to identify flower perfumes according to the chemical substance that predominated in each essential oil. But the resulting groups – indoloid, aminoid, benzoloid – sound more like the products of a motorway service station than the heady perfumes of the flower garden.

I suppose professional perfumiers need to do the same kind of thing, which is why the people who sell the stuff quickly try to work out whether you are a light, flowery kind of person, or a rich, musky type. Being flowery, I've always worn Vent Vert by Balmain, though the list of ingredients on the back of the bottle (Linalool, Benzyl salicylate, Hydroxyisohexyl 3-Cyclohexene etc) sounds anything but flowery. To perfumiers, florals are smells like lily of the valley, Verbena bonariensis, phlox and freesias. Hyacinths, nicotiana, pineapple broom, gardenia and lilac carry a headier cargo, heavy, musky.

The problem with smells is holding them clearly in mind – though no dog seems to think this difficult. Even the least intelligent hound picks up a good deal of information through its nose and a sniff round a trouser leg seems to them a surer guide to identification than a once-over with the eyes. Lying in bed, it's quite easy to picture what Viburnum carlesii looked like in April and May with its pink-tinged snowballs of bloom. Its precise smell (the best of the spring-flowering viburnums) is impossible to bring to mind. Yet smells are dangerously evocative. One sniff of a sweet pea can open up a whole Pandora's box of emotions: rows, reconciliations, a particular meal, a birthday party, my mother picking pinks in a soft yellow linen suit with mother-of-pearl buttons.

Certainly there should be plenty of scented plants in the garden in summer when there is the happy possibility of lying on the grass, letting the different smells drift over you like a mute piece of music. But a strong, sweet smell is also a characteristic of many winter-flowering plants, perhaps because there aren't so many pollinating insects around then and the flowers have to work harder to attract them. Chimonanthus, daphne, mahonia, sarcococca, honey-scented Viburnum bodnantense, witch hazel – they all smell superb and at a time of the year when we most need a lift.

But what about now when the summer still stretches in front of us? Roses are the thing, of course, and why anyone ever buys a rose without a scent is a mystery to me. As a race, the old roses still have the edge over more modern Hybrid Tea types, but deep cerise pink 'Wendy Cussons', though an awkward grower, smells richly of attar of roses, velvety crimson 'Ena Harkness' is gorgeously perfumed and, as you'd expect from the name, 'Fragrant Cloud', raised in Germany in 1968, is also worth growing for its smell.

In our last garden, I was particularly fond of 'Constance Spry', a modern climbing or shrub rose in the old-fashioned style with huge, cabbagey, double-pink flowers that carry a spicy smell. We planted it on the front of the house and at night the scent drifted through the open bedroom window in an almost hypnotic way. The damask rose 'Ispahan' with small, tightly-packed flowers of a slightly deeper pink was another winner for smell as were the Hybrid Musk roses 'Penelope' and 'Buff Beauty', both of which I've planted again in our new garden. They're flowering their heads off at the moment. But when, oh when, will I be able to smell them again?

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