Located behind the grade I listed Marwell Hall in Hampshire, the garden contains three styles of the 16th and 17th centuries - "knot", "parterre" and "kitchen" gardens.
They contain 113 roses, 96 lavenders, 64 lilies, 104 irises, 280 Dianthus and 940 box plants. The team laid more than 60 tonnes of topsoil and 6.4 tonnes of sleepers. Hillier supplied plants and advice.
Marwell chief executive James Cretney said: "The garden will help visitors uncover a piece of Marwell's heritage and experience herbs and flowers that were popular centuries ago and remain so today."
McIndoe added: "It's a great privilege to open Marwell's formal garden. Considering the terrible weather earlier this year, what Marwell has achieved is remarkable."
The garden was built by a team from Marwell, Sparsholt College students and the Community Payback team.