Chesters Walled Garden will close to the public

Mr Wylie, whose estimated worth is £150m, according to the latest Sunday Times Rich List, has decided the 18th Century two-acre site at Chollerford, Northumberland, will revert to private ownership when the lease runs out in May.

And the decision has left Susie - and heritage groups - shocked.

Susie, who leased the garden from the previous owners, said: "It is heart-breaking to leave somewhere I have spent nearly half my life working on.

"I have worked very, very hard and I have put a lot of love into it. The garden is very beautiful and has a special place in many people's hearts.

"It means a lot to a lot of people and many have been inspired by it, which is something to be proud of.

"Many people bring relatives and friends when they visit the North East and it is a main attraction on Hadrian's Wall," said Susie, who has written seven books on gardening and herbs.

She added: "Its naturalistic planting has made it a place of peace and somewhere that people feel refreshed."

In May a readers' favourites poll in BBC Gardener's World magazine saw Chesters come second in a league table of 28 gardens in the North of England.

A near neighbour of English Heritage's Chesters Roman fort, it was the walled garden of the adjacent Chesters mansion, once the home of 19th Century lawyer, Newcastle town clerk and antiquarian John Clayton.

Now Susie is looking for a site to create a new garden and to save as many of her plants as possible. Ideally it would be smaller than two acres and have been cultivated recently.

"I have a lot of creative ideas and I am keeping a very open mind," said Susie, who is encouraging people to visit the garden before it closes.

The garden has 900 different varieties of herbs, a range of plants which provide nectar throughout the growing season and, over the last 15 years, a local ornithologist has recorded 70 different species of birds.

Tom Higgins, director of communications for Hadrian's Wall Heritage Ltd, which helps look after the world heritage site, said: "At a time when Hadrian's Wall is becoming more and more popular we are sad to see its diversity being diminished.

"The people who run the garden have worked hard to build it up and it has helped attract visitors to the area."

A spokesman for Chesters House estate said: "The garden is part of a private estate and it makes sense for it to come back into private hands. It has always been the intention to keep the estate private and the garden is very close to the main house."

Anyone who can help Susie in the search for a new site should contact her on (01434) 681 483 or 07941 077595.

AN OASIS OF PEACE

Chesters Walled Garden is home to one of the largest collections of herbs in the country, with 900 different varieties.

They include the national collections of thyme, marjoram and burnet.

Centre-stage goes to the 30-metre-long thyme bank, at its best in late June, when its Persian carpet display of over 100 varieties of thyme in pinks, purples, whites, gold and silver attract the bees.

In the 1920s there was a staff of 15 gardeners. The north wall is a hot wall with a flue system and it was the job of young stove boys to keep the fires alight all night.

When Susie White came across the garden, it was being used to grow vegetables for the adjacent Chesters mansion, which was built in 1771.

The garden was overgrown and bare in many areas, with a 20ft chimney in the middle for the greenhouse boiler system.

Now the garden offers features such as:

A knot garden based on a design of 1617, from the first gardening book for women called A Country Housewife's Garden.

A section which contains herbs which the Romans would have grown in Britain. Hadrian's Wall runs 20 yards north of the garden and the line of a Roman road crosses the site at an angle.

Herbaceous borders 30 metres long by three metres wide.

Espalier apple trees more than 100 years old, a Mediterranean border and pond.

Woods of beech and yew shelter the garden, which slopes gently south to maximise the sunshine.

This all creates a microclimate which supports a range of plants such as eucalyptus and cistus that are not always guaranteed to survive a Northumbrian winter.