Some Mediterranean sages are hardy and can be picked fresh throughout the winter, to bring succour to the sick or cheer to a Christmas roast. As Nikos Kazantzakis, the author of Zorba The Greek, wrote: “He outstretched his hand, and cut a piece of the flowering sage shrub, and the smell rose like the mountains into his head.”

The most commonly grown sage, Salvia officinalis, has been prized for thousands of years. The Chinese reputedly valued sage tea more highly than their own. John Evelyn (Acetaria: A Discourse Of Sallets) writes in 1699 that they “happily exchanged three carts of theirs for one of ours”, and an Arab proverb claims that “he who has sage in his garden will never die”.

Like so many herbs, its medicinal uses are legion. Lung diseases, gynaecological problems, loose teeth and open wounds could all be cured, apparently. Notwithstanding this impressive list, there’s little doubt that sage tea does relieve sore throats. I’m not so sure, though, about sage ale or a 16th-century recipe where the herb is stewed in wine so “it might well have made the drinker more cheerful, if scarcely helping his memory” (Rembert Dodoens, A New Herbal, 1578).

Hardy sages, S officinalis and S lavandulifolia, are the easiest species to grow in Scotland. The most popular, Common sage, with its grey-green, “woolly” leaves, produces attractive lilac-blue flower spikes in early summer. It will grow to around 80cm with a metre spread, so, as an evergreen, pulls its weight in the herb garden. Another gem is the smaller and more compact S officinalis Aurea with oblong yellow leaves and purple-blue flowers. And the herb garden, or herbaceous border for that matter, would be brightened up by Purpurascens, Kew Gold and Tricolor. The other hardy sage, S lavandulifolia, has narrow leaves, stunning blue flowers and a good flavour.

These sages do need to be planted in full sun – my herb garden is in the most sheltered south-facing part of the garden, close to the front door and handy for picking. Sages will not tolerate wet conditions although they’ll cope with all our winter rains, provided the soil is free-draining, otherwise they’ll simply rot. While they won’t put on any growth just now, the leaves can still be picked. Without the benefit of the summer sun, though, the essential oils will be sluggish, but you can invigorate them if you dunk the leaves in hot water for a second.

We can also grow some of the 900 other species of sage. The tender or half hardy ones need protection over the winter months and can still be lightly picked. S elegans, pineapple sage, with its bright green leaves and slim, red flowers, does have a pineapple flavour, while S microphylia, blackcurrant sage, reminds us of that fruit. And S fructicosa – Greek sage – has a delicate smell of lavender. All these species should be grown in pots and brought into the greenhouse or conservatory over winter and cut back to stimulate new growth. Sages will often become quite large, given the chance, but it’s perfectly easy to take cuttings and discard a shrub when it outgrows its pot. This will also prevent woody growth.

Interestingly, when we imported some of these tender species, we left behind the insects and birds that play an important role in their native countries. There’s the puzzle of why S elegans, pineapple sage, rarely sets seed, despite flowering constantly from late spring onwards. In fact, it’s flowering away in the greenhouse at the moment. The flowers clearly have stamens that produce the pollen needed by the stigma. At first glance, it looks as if the plant is sterile or is not self-fertile. It should be able to attract pollinators: its flowers are bright and it produces nectar, though there is no sturdy lip to act as a landing stage for insects. The point is that S elegans is a Mexican shrub that relies on hummingbirds for fertilisation. Birds see red colours well, unlike bees which are attuned to blues and purples, and hovering hummingbirds can drink the nectar without standing on a lip. In fact, the only native pollinator that shows the slightest interest is the hoverfly. So while it’s just possible to get viable seed, the odds are pretty long. On the plus side, this infertility provides us with an endless succession of flowers as the herb frustratedly awaits its hummingbird.

So sages are useful plants in the winter and, given that toads are hibernating at the moment, we can safely ignore the advice from the 17th-century herbalist William Cole (Adam In Eden, or Nature’s Paradisem, 1657): “Be sure you wash your sage for fear that Toades, come to relieve themselves being overcharged with poyson, should leave some of the venom on the leaves.”

For thousands of years, people have recognised that sage is an important plant. Sage oils contain a range of valuable chemicals useful in perfumery and aromatherapy, in cosmetics, in dental-care preparations and in the food industry where they are used not just as flavouring for such things as condiments, cured meats and liqueurs but also as antioxidants which act as preservatives.

The quality of the active ingredients extracted from species of sage varies markedly according to the time of year and the conditions under which the plant has been grown. So old injunctions to cut sage in May have a sound scientific basis.

Sage is becoming bigger business. The Mediterranean climate is ideal for large-scale production. In 1999, Spanish farmers exported 40 tonnes of sage oil, while Morocco exported no less than 139 tonnes of dried leaf in 1994. Although exact figures aren’t available for Turkey, sage production by small-scale farmers is thought to be very large. Again, we don’t have precise figures for Portugal, France, Italy, Greece and Egypt, though they all produce large quantities for domestic use and export (Sage: The Genus Salvia edited by Spiridon E Kintzios © 2000).