The details for the gardening version of London Open House Weekend have been announced – where us mere mortals are allowed to wander around those closed off garden squares that act as glorified roundabouts in the posher parts of London – or peek like nosy people at private gardens that people have managed to create in our polluted atmosphere.

Unlike the Open House weekend which is completely free of charge, you do have to pay to get into the gardens. Fortunately, the price is just £7.50 if brought in advance and acts as an unlimited pass for the whole weekend, which is frankly rather good value for money. That also gets you a copy of the printed guidebook.

The Open Garden Squares event takes place on the weekend of June 12 & 13, 2010, so time to mark it off in your calendars.

There are, at time of writing, some 166 venues open to the public over the weekend, and while their website has a list, I tend to find that for these sorts of things, a map works best. So I made one!

Click here for my super-dooper magic map thingymajig

..or you can use their list (boo hiss!) if you prefer.

Many of the gardens have various additional events going on from guided tours to music, refreshments or exhibitions.

The vast majority are turn up and look around, but a couple of rather interesting gardens have to be pre-booked, you need ID with you and no photography permitted. These stringent restrictions become understandable when you realise the venues are HM Prison’s Wandsworth and Wormwood Scrubs. To reserve a spot, you have to buy tickets then when they arrive, the booking details will be provided at the time.

In additon, some venues have guided tours of their gardens and their history:

Particularly notable though are the Brunel Museum – tiny garden, but access to the floodlit tunnel and main shaft chamber; The Pump House Educational Museum will be open at Lavender Pond Nature Park and the Chapel will have a rare weekend opening at Brompton Cemetery.

Tickets are now available online or via the electric telephone at 020 8347 3230 (Mon-Fri 9am-6pm). Some of the venues will sell tickets on the day, but they cost a bit more at £9.00 each.

Those fine chaps (and chapesses) over at the London Parks & Gardens Trust, who organise the annual Open Gardens Squares Weekend have launched a new project to create an online database of every notable garden and park in London.

The 3-year project commenced in December 2008 and will be completed by late 2011, with new research, photography and historic images brought in to illustrate the entries.

In the first instance it includes core information on sites on the Inventory Database, which now comprises over 2430 entries, and these are gradually being uploaded.

They say that they wanted to make some information available now and to give people a taster of the full website, but they’d also like to encourage people to contribute comments, knowledge and feedback – so if you know about a garden or park (or geekish database knowledge), here is your chance to contribute to the project.

Details over at the The London Gardens Online Project