All around SE1 residents are busy growing fruit, vegetables and flowers to enter into the show which is being held to mark the centenary of the death of Octavia Hill.
For an entry form, check the BOST website.
Judges include representatives of local businesses, artists and the National Trust.
Octavia Hill herself may be visting the show dressed in Victorian costume.
There will be local produce to try, local stall holders selling their wares, Victorian games, Punch and Judy, dancing, folk music, bouncy castle, face painting, arts and crafts and lots more.
Even if you haven't had a chance to 'grow your own' this year you still have the chance to enter a 'paper garden' which you can create on the day and enter for judging at 5.15pm.