The Sir Harold Hillier Gardens is an arboretum comprising 72 hectares (720,000 sq metres) accommodating over 42,000 trees and shrubs in about 12,000 taxa, notably a collection of oaks, camellia, magnolia and rhododendron.

The Gardens are located 5 km northeast of the town of Romsey in Hampshire, England, and were formerly known simply as the Hillier Arboretum, founded by nurseryman Harold Hillier in June 1953 when he acquired Jermyn’s House and its grounds.

The arboretum was given to Hampshire County Council in 1977 to be managed as a charitable trust. Sir Harold Hillier was knighted in 1983, just two years before his death at age 80 in 1985.[1]

The Gardens were listed as Grade II on the National Register of Historic Parks and Gardens in 1997.

Besides growing many plants rare in cultivation, the Gardens grow over 200 threatened plant species and participates in a variety of conservation programmes, including collaboration on biodiversity projects on a local, national and international level.

At a press day in 1964, a journalist asked Sir Harold what he thought of the fledgling garden plant conservation movement. “I shall tell you what I think,” he replied. “Whilst other people are talking about it I am doing it, I am planting, planting, planting and I would urge others to do the same.”