Containing more than 3,000 roses, it is the realisation of a long-held dream of Wynyard Hall's owner, Sir John Hall and has been designed and planted by landscape architect Alistair Baldwin.
"The walled garden will be breathtakingly beautiful," said York-based Baldwin. "Visitors will see a truly dazzling display of roses, in a design which pays tribute to the ancient heritage of the walled garden, yet takes it firmly forward into a new stage of development."
The £1.6m Walled Garden development, to the north of the Hall itself and within the estate's 40ha of grounds, will also house a visitor centre, shop and café, stocking and serving locally-sourced goods and produce.
Thirty new jobs have been created by the re-development of the Walled Garden; the second stage in a rolling programme of work to create The Gardens at Wynyard Hall – which will eventually cover 1.6ha and be one of the largest rose gardens in the UK.
The first stage, adjacent to the Walled Garden, was the £1.7m installation of a Grand Marquee and management suite, for weddings and large scale corporate events and further stages will include a £2m investment in the creation of a cookery school, children's garden and designated walks through the estate.
Property magnate Sir John Hall, who grew up in a Northumberland pit village, said: "When I was a lad I used to watch my father grow roses in the little strip of garden in front of our cottage and I decided, there and then, that one day I would have one of the most spectacular rose gardens in the country – and this is just the start."
Local suppliers and businesses have been deployed across all areas of the development, including the build, landscaping, fitting and design.
"It is magnificent beyond our wildest dreams," said Allison Antonopoulos, managing director at Wynyard Hall Hotel. "It has been years in the planning, many months in the developing and will, we hope, give a lifetime's pleasure to all who come to see it."