True grit: Horticulturalist Beth Chatto's remarkably hardy gravel garden

To get to Beth Chatto's house you turn down an unremarkable lane just near a petrol station in the heart of Essex. Here is the celebrated gardener's residence itself: a white suburban bungalow that sits plump on well-mown green turf. And though it's signposted well, it remains a surprising prologue to one of Britain's most interesting and exotically original gardens.

Chatto's interest in horticulture began when she was a 1960s wife, mum and flower-arranger with an enthusiasm for odd-looking shapes to fill up a vase. She found her heart swelling with love for these unusual plants, and she started to grow and sell them, beginning to fill up polytunnels rather than vases. As her nursery grew, so did her own garden. You can see the archaeological traces of the middle-England golf-course-garden, if you look hard enough. There are long swathes of lawn, a perfect golf-ball-swallowing pond and small trees and shrubs dotted along island beds. But the plants themselves are a real surprise.

It's a particularly great place to visit in hot, high-holiday summer. Here is an excellent mid-August lesson in how to survive the season: trees in the main garden provide a wonderful body of shadow to walk under, and the water is hovered over by dragonflies.

The effect is captured beautifully in the new book A Year in the Life of Beth Chatto's Gardens (£16.99, Frances Lincoln), which shows off especially nicely Chatto's finest summery achievement: the gravel garden, finished in 1992, when she was almost 70. (Gawd, I hope I can manage anything like that at 70: just the digging, the digging…)

The gravel garden had a fairly unpromising start. For one thing, it used to be the car park. But where better, as talk circulated about global warming in the final years of the 20th century, to find a flat spot to show gardeners how to manage without a hosepipe?

Chatto and her husband Andrew were fascinated by wild plants and their adaptation to native habitats; rather than fighting Colchester's North Sea winds, baking summer sun and average 20 inches of rain, this garden would embrace it. The Chattos chose plants from similar areas of the world, with one requirement: the garden would never get watered.

That's a strict rule to lay down, but Chatto knew what she was building: a garden to inspire and inform those suffering under hosepipe bans. It sounds a horribly practical remit. Yet take a look at the gravel garden today, with tall soft grasses just starting to seed, spiky yuccas and ferocious sea holly in flower; it would be very difficult not to be seduced.

Plants here are not confined to flowerbeds, but are planted under the gravel itself. This adds another layer of informality, and of water conservation: the tiny stones act as an excellent layer to stop evaporation and keep roots cool and moist even on boiling hot days. Colour is important; though many of the garden's denizens are silvery and grey, there are strong splashes of lime green from little euphorbias, and mauves and yellows zing out against each other.

The yellows are particularly interesting: I'm not a big fan of yellow but Chatto's pale-primrose hollyhocks can creak me into enthusiasm, especially in combination with metallic-purple allium sphaerocephalon and the brighter yellow of verbascums going to seed.

There are even trees here, despite the baking dryness. One very pretty leaf you may recognise is Rhus typhina, the stag's horn sumac. Its leaves hang in little triangles like bright-green bunting, turning a spectacular red in autumn. Sumac trees are a close relative of those producing the tasty Lebanese salad spice, but I wouldn't recommend harvesting these: their lovely red fruits are worth keeping on the tree, anyway. (A tree from crocus.co.uk is £13.99.)

And in the very hottest of weather, the garden is a fantastic way to round off a visit. Looking delicious as dark pools of shadow spread over the gravel, there's no better place to spend an afternoon.

The Beth Chatto Gardens, Elmstead Market, Colchester, Essex, are open daily. Autumn colour walks take place in October; see bethchatto.co.uk for details