“It is a plantsman’s gardens and famous for its peony borders and its magnificent central herbaceous borders which are now at their best,” said Lady Graham.
“It is listed Grade II as is its Orangery.
“In recent years we have created a Potage.”
Norton Conyers, house and garden, have belonged to the Grahams family since 1624.
Recent excavations have revealed that parts of the house, which is closed to visitors this year, are Anglo-Saxon.
The house’s exterior has distinctive Dutch-style gables and its interior contains fine 18th century plaster ceilings in the principal rooms.
The garden is five minutes’ walk from the house. Laid out in the mid 18th century, it retains the essentials of its original design, together with sympathetic replanting in the English style.
Norton Conyers’ walled garden, which is tended to by a network of volunteers, is open throughout the year Monday-Friday, 10am-4pm.
Amnesty International UK work to protect human rights wherever justice, freedom, truth and dignity are denied.
It works to investigate and expose abuses, educate and help transform societies to create a safer world.
Admission for Sunday costs £5 for adults.
Amnesty supporters will be selling homemade teas and unusual herbaceous plants grown in the garden are for sale.