In the autumn of 1892 a group of leading citizens and senior civil servants met at the City Hall to plan the launch of a local Horticultural Society.

Their purpose was to create a society that would give instruction in the growing of fruits, vegetables, and flowers, and provide suitable conditions for exhibits of the produce of members’ gardens in due and proper season.

The inaugural meeting was on January 17, 1893, with "some thirty gentlemen present" to listen to a lecture on the newest and best horticulture techniques.

The Dominion Horticulturist for Canada, Dr. W. T. Macoun, was an active supporter as well as serving as President of the Society for one year.

It published pamphlets describing how to grow flowers and vegetables; it distributed seeds and offered substantial prizes.

The early members also aimed at the beautification of Ottawa and, working without a city Parks and Recreation Department, undertook many projects that would now be considered the responsibility of local government.

One major project undertaken with the Parks Commission before the turn of the 20th century was the planning of plantings for the west bank of the Rideau Canal.

It developed many wartime gardens, provided seeds, plants, labour (if needed), and instructional lectures to demonstrate how to "Grow Food and Help Win the War".

During World War II OHS members procured public lands, paid for ploughing and tools, and provided "know-how" for what were known as "Victory Gardens".

The Society presented the first official street tree policy to Ottawa city politicians and did much to promote the adoption of the trillium as the floral emblem of Ontario.