The Cottesbrooke Plant Finders' Fair takes place on 27-29 June at Cottesbrooke Hall & Gardens in Northamptonshire.
Organiser TJM Associates director Therese Lang said 22 exhibitors had confirmed and 11 stands were still available.
She added: "It will be small but perfect, in a beautiful location. We're trying to raise the bar."
The fair is modelled on the Courson garden fair, held outside Paris, and Bingerden in Holland. Lang said: "This event has been long-awaited. There is an untapped market in the UK for an event of similar calibre, charm and flair."
Applications for the fair will go before the selection panel, which includes garden designer James Alexander-Sinclair.
Cottesbrooke Hall is privately owned and won the HHA/Christies Garden of the Year Award.
For details contact Therese Lang on 01373 812223 or email firstname.lastname@example.org.