The Marquess of Cholmondeley, who runs Houghton Hall in Norfolk, said charitable trusts were suitable for large properties open to the public over long periods.
Houghton includes a walled garden maintained by the Cholmondeley Gardens Trust Charity. More generous tax incentives were the key, he said.
"Assuming our historic buildings are worth protecting, the best way is to give generous tax incentives for those putting money towards their upkeep.
"This will appeal to a wider cross-section of owners of exceptional areas of landscape, bridges and historic townhouses."
Ministers have touted the idea of shifting ownership of parks and green spaces from councils to trusts and volunteers as part of the "Big Society" localism agenda.
Historic Houses Association president Edward Harley said there was a lot that Government and its agencies could do to help historic gardens and houses.
"These would be at no or very little cost and include fiscal incentives, closer collaboration with the Heritage Lottery Fund and a root-and-branch look at red tape."