The new London Gardens Online website, www.londongardensonline.org.uk, goes live on 8 May and will include an inventory of green spaces of local historic interest.
"This is Trust’s biggest project since it was inaugurated as an independent charity at the Chelsea Flower Show in May 1994," said a spokesman.
"It builds on our aims: to increase knowledge and appreciation of London’s open spaces, including its parks, squares, gardens, cemeteries and churchyards.
"London Gardens Online gives a unique insight into the diversity of these open spaces: minute and expansive, manicured and natural, ancient and more recent."
The website is targeted at green-space professionals such as landscape architects, locals, tourists, students, teachers, planners, surveyors and property managers.
"The Olympics are almost upon us and the online tool is poised to inform not only this summer’s visitors but those seeking places away from the sporting hullabaloo."
Over 2,500 spaces across Greater London have been researched for the inventory. All are at least 30 years old and have formal layouts or important social history.
They can be searched by borough or type, from historical cemeteries to squares and commons.
Keywords pinpoint bandstands, lidos, a ha-has, or crinkle-crankle walls.
Each listing gives the site’s brief history; details of how to get there; who manages it; events; opening times; and accessibility.
"As part of the project to convert the inventory into the website, a team of picture researchers has been finding historical images to illustrate site entries."
Sally Williams, the trust’s inventory keeper, was supported by the Pilgrim Trust, J-Paul Getty Junior Charitable Foundation, English Heritage regional capacity building funding, private donors, and the Paul Mellon Centre for Studies in British Art.