There has been a green revolution in primary school playgrounds. Litter-strewn Tarmac has been transformed with tubs and troughs brimming with flowers. Reincarnated old tyres, sinks and barrels sing with salad crops. And right outside the classroom window, miniature cottage gardens and shady ponds create a rich habitat for birds, fish, insects and a multitude of wildlife.

Some schools have even fashioned open-air theatres, mazes, murals and art trails. Others have installed bird hides and boxes for hedgehogs and bats.

“A garden is one of the most powerful teaching aids we’ve got,” says Sue Johnson, the Royal Horticultural Society’s education officer, based at its Wisley garden in Surrey.

It puts children in touch with the natural world and provides an endless source of exploration and investigation. Just as important are the social benefits - team work, taking responsibility, and reducing vandalism through a sense of ownership.

When planning a garden, the first question to ask yourself is what you want to teach, says Sue Johnson, not what you want to grow. Gardens, of course, can be the starting point of almost every aspect of the science curriculum, but they can also inspire imaginative writing, art and music.