More than 8,000 schoolchildren visit the world famous Sir Harold Hillier Gardens in Hampshire each year, not only to see some of the 42,000 plants in the 180-acre grounds but also to learn about mapping, mathematics, history, geography and Ancient Egypt.

The schools ask education officer Mary South to devise a programme on a certain topic. She sets about this with a gusto that makes you suspect that this ex-secondary school head of biology gets the same enjoyment out of her games and puzzles as do the children themselves.

“All our programmes are experience based, not chalk-and-talk,” she says. “We don’t use worksheets; if the pupils are busy ticking off boxes they fail to experience what is going on around them.”

The Victorian Plant Hunters programme is one of the most popular. The children, in Victorian costume, turn themselves into intrepid painter Marianne North, the Englishwoman who travelled twice round the world 100 years ago in search of plants, which she captured on canvas in their natural habitat.

“We give them verbal directions, and then with map and compass. They soon learn that mapping is the best way. They have to find a suitable place to set up camp and then identify certain trees as sacred. This is a lead-in to teaching them about other people’s culture.”

On top of that comes the plant-hunting itself and the excitement of locating the places you’ve travelled to on a huge laminated map of the world. That programme won a Sandford Award for Heritage Education.

A Hampshire school challenged the ingenuity of Mary South and her helper, Carla Thomas-Buffin, when they asked for a programme about Ancient Egpyt. Papyrus, which is a sedge, rushes for writing and reeds all played their part, as did hieroglyphics spelling the word “pyramid”, honeycomb and figs, cedar of Lebanon, sacred amulets and a toy cat which was enthusiastically “mummified” with yards of loo roll.

Or there is the seed game where children “become” a plant that has produced 20 seeds; they make moves which determine the fate of those seeds.

“They’re so competitive,” says Mary. “But if they start crowing when they have 10 seeds left and the next team has only five, I turn logic on its head and say: ‘The plant has reproduced itself and has also done its bit for the food chain by feeding slugs, birds and mice. So which plant is the most useful?’ That makes them think.”

The gardens are used mainly by junior and infant schools. But every September Mary runs bonding days for the new intake at secondary schools. Mixed groups of 10 or 12 children set off with maps to find 15 stations scattered throughout the gardens. There they perform tasks such as co-ordinated plank-walking, or water-gathering. “Often it is the children who are a problem in class who get the most out of the activities,” says Mary. “We’ve even had voluntary mutes speaking, they’ve been so overwhelmed by it all.”

Adrienne Benton, who teaches Year 2s at rural Wellow School, near Romsey, says her children come back “fizzing with excitement and with a lot of creative ideas” after a visit. “One of my classes was so excited by what they were doing, they spontaneously burst into song to entertain Mary. It was one of those wonderful moments.”

Jennifer Craig has been taking Year 2s and 3s to Hillier’s for 10 years. Her school, Penhale Infants, is in inner-city Portsmouth. “The education programme is ideal for our children, most of whom have no garden at home and are not used to green space,” she says. “One year a seven-year-old had hysterics in a clump of bamboo, unable to cope with the quiet darkness under trees. I can’t sing Hillier’s praises often enough because they recognise that sort of problem and have ideas that cope with it.”

Mary South has a huge desire to communicate the precious nature of the environment to all children. She speaks of the “appalling sadness” of watching inner-city children finding it hard to come to terms with the silence of large tree-filled spaces. “They have to make a noise to fill the silence. Unless you get young people to have some better empathy with the living world, you’ll destroy it.”

Education Service, Sir Harold Hillier Gardens, Jermyns Lane, Ampfield, Romsey SO51 0QA. Tel:01794 368787. Book first. Children pound;1.50 each, accompanying adult free