Garden of interest or gardening exhibitions near Victoria station (London)

There are a couple of Squares with gardens nearby, but you have to have a key to get into them, so they're not much use. I don't know of anywhere near with a garden exhibition either, so the only thing I can suggest Green Park or St. James Park, both of which are just a spit away past Buckingham Gate. St. James' is the nicer of the two, I think, mostly because it's got a lake. I think St. James has a tube station if you didn't want to walk or take a bus.

Thanks for the info - St James' park sounds great!