You can tell Chagford Church of England primary school, on the north-east edge of Dartmoor, takes its gardening seriously as soon as you spot the colourful hanging baskets over the entrance. They contain geraniums, busy lizzies, petunias and diascias, all planted by children at the school’s thriving after-hours gardening club.

Inside, the lobby and corridor are decorated with photographs taken during a recent visit to the Royal Horticultural Society’s garden at Rosemoor, Devon - about an hour’s drive away - and with drawings done by the children during a gardening project. Some show the differing rates of growth between plants in full light and those in degrees of shade; others illustrate an experiment in which pupils placed cut carnations in a solution of food dye to change their colour.

The teacher responsible for the display is Stephanie Whitcher. As well as being class teacher for Year 3, she is founder and organiser of the gardening club, which meets for an hour after lessons every Monday. Mrs Whitcher has been at Chagford for five years. In her previous post, at Littleham primary school near Exmouth, she organised gardening so successfully that the school won the Royal Horticultural Society’s junior garden design competition and had its design built and displayed at the Chelsea Flower Show. As a result of that, she was appointed to the RHS education committee and has since been awarded a fellowship by the Gatsby Technical Education Project to research ways of taking the national curriculum into the garden.

At her Chagford job interview she stressed her determination to promote horticulture, and she has been as good as her word. “There wasn’t much going on when I arrived here,” she says. “There was a greenhouse in front of the school but it wasn’t used much and was about to be taken down.” She had a new one built behind the school and a group of children began raising seedlings in it. Within a year they were busily digging out vegetable plots on the lawn alongside, to grow the seedlings in.

Membership of the gardening club fluctuates according to the season. In the autumn and spring terms it can number as many as 20 - out of a school of around 200 - but in the summer it dwindles to half a dozen or so because of competing extra-curricular activities, especially sports. The hard core are true enthusiasts, and this is evident from the results. On the vegetable plots, potatoes, leeks, courgettes, French beans, radishes, lettuce, sweet corn, cabbages and sprouts are all thriving, although a visit from a careless cat has made germination in some of the rows patchy. Chemical pest control is barred, so the children have put broken egg shells around the rows to keep away slugs.

The strawberries are developing well and so are blackcurrants, gooseberries, plums and apples. In the greenhouse, tomatoes are roaring away. In the holidays, when the children are not available for watering duties, the caretaker steps in. He picks the ripening fruit but always ensures that some remains on the vines for the start of the autumn term, so the children can see how they have developed.

The school also has a silver garden, created for its 25th anniversary, with silver-leaved plants such as artemesia and lavender, and silver-grey grasses.

Chagford used to be a tin-mining centre and the garden includes a mosaic representing the traditional tinners’ rabbit symbol - a circle of three rabbits chasing each other. This is now being moved to the new millennium garden at the front of the school, designed by the children and the winner of a competition sponsored by sugar producer Tate and Lyle, which is paying for the work.

Though naturally proud of such achievements, Mrs Whitcher is keen that her fledgling gardeners should primarily enjoy themselves. “It’s a club, after all,” she says. “I mention things such as the environment and sustainability but only incidentally. I want it to be fun, that’s the main thing.”

One of the older boys confesses that a big attraction for him is the chance to get dirty without getting into trouble. For others, the thrill is in following the growing process from the beginning and finally reaping the harvest.

“You should see their faces when the potatoes are dug up - some of them had no idea how potatoes grow. Last year, we grew enough for one school dinner and washed and peeled them. We did the same with broad beans. Children aren’t known for liking broad beans but the gardening group went round and told the others they had grown them and there were hardly any left over.”

The children have relished tasks that include planting trees on a local estate, making compost converters out of plastic lemonade bottles and donning thick woollen socks to collect seed from the school’s good-sized wildlife garden. (The seeds stick to their socks and are later sorted and sown.) Last year, a parent donated hundreds of daffodil bulbs, which the children planted in front of the school. When they flowered in spring, Mrs Whitcher set up a daffodil project in which her class wrote about the plants and drew pictures - a practical example of how gardening can be integrated into the curriculum.

“Some of the children are outdoor types,” she says (many are from farming families). “They are happier out there doing something, rather than doing the same thing in the classroom.” Parents are enthusiastic, too. They support an annual sale of bedding plants that the children raise from seed and they contribute in kind: one horse-owning family sends over a load of manure every winter. Samantha Vincent’s son, Grant, is one of the keenest gardeners. “He loves working in the garden here,” she says. “He comes and tells us how to do things. He told his granddad about keeping slugs away with eggshells - his granddad didn’t know that.”

Mrs Whitcher is aware that children’s interest in gardening often fades as they become teenagers; but she refuses to let this discourage her. “I think you should expose children to what they can do in the garden, even if it’s only for a couple of years. Then, when they get older, many of them will rediscover that interest.”

The RHS Garden at Rosemoor offers free guided visits to schools in Cornwall, Devon, Dorset and Somerset. Details from the education officer, Sarah Chesters, Rosemoor, Great Torrington, Devon EX38 8PH. Tel: 01805 624067. Email: rosemooradmin@rhs.org.ukThe Devon Gardens’ Trust (tel: 01392 252404) is keen to establish links with schools. Contact Joy Williams at 12 Bicton Street, Exmouth EX8 2RU for free advice and ideas on developing school grounds