The garden is situated on the Whiteknights campus of the University of Reading about two miles south of the town centre. It was once the home paddock of the now demolished ‘Wilderness’, a Victorian house which was built in the remains of a famous landscape garden created at White Knights by George Spencer, Marquis of Blandford (later 5th Duke of Marlborough) between 1798 and 1819.
A small botanic garden was established here by the University in 1972 when the Department of Botany moved from London Road to Whiteknights. In 1987 the Department of Horticulture and Landscape also moved to Whiteknights and work began to extend and enhance the Botanic Garden to meet the wider teaching and research requirements of the new School of Plant Sciences. At this time Richard Bisgrove, garden historian and Director of Landscape Management at the University of Reading, drew up a plan for the garden which included features that still provide interest now throughout the year.
In recognition of its new role the garden was renamed the Harris Garden in memory of the late Professor Tom Harris (1903-1983), a distinguished palaeo-botanist at the University of Reading and a renowned gardener.
In 2010, with the closure of Plant Sciences, responsibility for the main part of the garden passed to the Facilities Management Directorate of the University and a major revitalisation programme began. The Walled Garden is, however, under separate management and there is limited access because of its use for scientific purposes.