Poke around private and little known London gardens the weekend of 8-9 June.
Over 200 gardens throw open their gates to the public for Open Garden Squares Weekend, a chance to get into those green spaces that are usually out of bounds. Gardens range from historical private squares (like Chester Square, Belgravia) to contemporary roof gardens (like on the IPC Media building on Southwark Street), prisons (HMP Holloway!), herb gardens (Eastbury Manor House) and barges (Downings Road Moorings at Tower Bridge).
There are events all over London so there should be something happening near you. It's not just flower appreciation either: there's a gin bar in Arlington Square, edible walks in the City of London and art installations, music and Punch and Judy elsewhere. A weekend ticket costs £10 in advance, £12 on the weekend itself, children under 12 go free. Check the full list of gardens for opening times and restrictions.
Similar-but-different is an open gardens event in Greenwich on 2 June and 9 June, raising funds for restoring St Alphege's church. Six or seven houses are opening up on each day, sometimes providing Pimms, wine or teas. Gardens cost £3 each to enter or £10 for the full day. The Greenwich Phantom has more information.
Open Garden Squares Weekend is organised by the London Parks and Gardens Trust and runs 8-9 June. For more information and to buy tickets, see the website.