This Is the Centrepiece feature of my Front garden in 2005. Each year I plant it differently, with one or two varieties of Plants. I also have a Basket suspended on a pole, which sets it off in the middle of the feature. Usually in that, I use Trailing Surfina Petunias, which last year were "Burgundy" in colour, with "White" Lobelia and a "Genii" Fushia, to finish off the effect, a bit like a Water fountain. At the base were the F2 Petunias, with mixed Geraniums towards the pole in the Centre.
This should all last till Mid-October with regular feeding. I use "Miracle-grow" Plant feed, added to water and strirred. Fed once a week in mid-summer. It just makes the flowering season last just that bit longer, till the Frosts arrive!