Inspiration for next year’s window boxes? The red, orange and yellow flowered bidens (on a bridge over the canal at Pantin) are varieties from the new Hawaiian Flare series, introduced by Japanese plant breeder FlorSAIKA in 2012 and now widely available in Europe.  The rich orange-red flowers contrast beautifully with the purple foliage of the tradescantia but I was tempted to improve the mix by sneaking out the one pink begonia!