It is one of those days we’ve had a lot of this summer, bursts of sunshine punctuated by downpours. When the sun comes out the colours of the herbs come into their own — the brilliant orange of marigolds, bright red poppies and beautiful lavender flowers laced with the wonderfully aromatic scents of sage, rosemary and thyme.

Above all there is an overwhelming sense of tranquillity punctuated only by the sounds of birds, bees and the sight of the odd rabbit hopping around.

The scene is Weleda UK’s 15-acre (6-hectare) plot of herbs near Ilkeston, in Derbyshire, where the company, which produces natural- health products, grows more than 300 species for use in herbal and homoeopathic remedies, toothpastes, shampoos, lotions and potions. Growing its own ensures freshness, availability and sustainability.

The Derbyshire rabbits aren’t too popular with Weleda’s head gardener, Michael Bate, because they dig up whole plants to get their food. But rabbits aren’t the biggest threat to the planet’s herbs — we are.

A report last year by Plantlife International, the wild plant conservation charity, claimed that the £11 billion global herbal medicine industry is causing 4,000 to 10,000 herbs worldwide to become endangered. Unfortunately, the majority of the herbal medicine industry are not doing their bit to ensure survival and Weleda is one of just a few natural-health products companies growing its own and buying from sustainable sources.

An astonishing 80 per cent of the world’s population relies on herbal medicine as their primary healthcare. Often the cost of drugs is far beyond the reach of many in the Third World but also, in many cases, local cultures have a long tradition of using herbal medicines that have served them well over the years.

In the UK we spent £87 million on herbal remedies in 2004, according to the market research group Mintel, which was an increase of more than 56 per cent on 1999 — with no let-up in annual growth. And all kinds of herbs traditionally used by medicine men, native tribes and Indian and Chinese doctors are now commonly available on the shelves of our local health-food store.

While many of us may applaud ourselves for embracing a natural lifestyle, the Plant- life report also claims that two thirds of the 50,000 medicinal plants used in the herbal industry are harvested from the wild, and herbalists talk of varieties that are no longer available at all.

It is almost impossible to police the harvesting of herbs around the world unless communities choose to do it themselves or herbal companies set up sustainability projects.

The Sioux Indians of South Dakota have used echinacea for hundreds of years to fight infection and to heal wounds and snake bites. When they collect the plants, to prevent the extinction of the species, they never pick the first one they see in case it is the only one of its kind left. Unfortunately, not everyone has such high ideals and echinacea is being illegally harvested even in protected areas in the United States.

Duncan Ross of Poyntzfield Nurseries, on the Black Isle, north of Inverness, is a biodynamic horticulturist who grows several endangered species there. “Anyone with a sense of sustainability will pick only a small proportion of the seeds they find with the landowner’s permission,” he says. “But people who are simply in it for a quick buck do a lot of damage.”

Endangered herbs cited in the Plantlife report include arnica, popularly used in homoeopathic remedies for bruising; goldenseal, prescribed for digestive problems and wound healing; American ginseng, traditionally an aphrodisiac but now more usually dispensed to boost energy levels; and liquorice, often used in herbal and conventional medicines for stomach ulcers. The commonly known kitchen herbs, oregano and thyme, are also being overharvested in some areas for their medicinal properties.

It is often the type of harvesting that can cause problems. In the case of bearberry, or Uva ursi, a herb used to treat bladder conditions, only the leaves are required but the whole plant is uprooted for expedience. This happens commonly and as Ross explains: “If you pick the whole plant it doesn’t seed again or regenerate.”