Plantswoman
Jean O'neill Of The Maine
16/01/1916 – 05/07/2008
Architect
George Oakley
??? – ???
Businessman
Henry Roger Keene Oakley
??? – 01/01/1940
Architect
George Oatley
01/01/1863 – 01/01/1950
Architect and builder
William Oldham
31/12/1739 – 31/12/1813
Nurseryman
Henry Oldroyd
??? – ???
Architect
Robert Dudley Oliver
??? – ???
Architect
Thomas Oliver
13/01/1791 – 09/12/1857
Designer
Frederick Law Olmsted
??? – 25/04/1822
Nurseryman
William Oram
??? – 31/12/1719
Historian
George Ormerod
19/10/1785 – 09/10/1873
Garden designer
Peter Orriss
??? – ???
Architect
P. B. Osborn
??? – ???
Agriculturalist
Robert Osborne
??? – ???
Architect
Louis Osman
??? – ???
Garden Designer
Piet Oudolf
27/10/1944 – ???
Architect
Edward Augustus Lyle Ould
01/01/1852 – 01/01/1909
Engineer
Benjamin Outram
31/12/1763 – 21/05/1805
Architect
Thomas Ellis Owen
31/12/1803 – 01/01/1862
Architect
William Owen
??? – ???