Founder and organiser Therese Lang of TJM Associates likened the fair to a smaller British version of the Courson event in France. Cottesbrooke attracted 29 exhibitors in its first year.
Her forte, she said, has always been to champion the smaller, specialist exhibitors "and to help make them famous".
For the first time, this year's event will also have talks from top gardening names Dan Pearson, James Alexander-Sinclair and Alys Fowler.
Cottesbrooke Hall head garden Phylip Statner will also be among a panel taking gardening queries from visitors.