The seventh Garden Store outlet will open at Easter.
The garden centre resides in the walled garden of Elton Hall, a part Gothic house which has been in the Proby family since 1660.
Company founder and MD Marcus Eyles said that it was "very exciting to be able to acquire another site in the grounds of a stately home as we operate very successfully at Charlecote Garden Store which is in the walled garden of Charlecote Park, which belongs to the National Trust."
The store was originally set up by Blooms of Bressingham in 1993 and has a "orangery-style" garden & gift shop with a restaurant. The plantarea is extensive and it is all contained within the grade one listed walled garden.
Stevens said: "Our formula fits stores like this very well as we concentrate on plants and core gardening."
There are now, with Elton Hall, seven stores in the Garden Store Group, based at Billing - Northampton, Whilton Locks - Daventry, Charlecote - Stratford-upon-Avon, Newton Regis - Tamworth, Studley Green - High Wycombe and Pavilion – Wolverhampton.
The previous tenant Roman Way Garden Centres will continue to run their other successful garden centre near Milton Keynes.