Horsetail and creeping jenny - very compatible, they both like it wet. This kind of plant combination is fairly easy to maintain because it doesn't need a drain hole in pot, you can fill it with many days worth of water, even in hot weather.
Hameln' , a dwarf fountaingrass, crowns a bed of white petunias and 'Purple Dome' aster. The bright white draws your eye to the base of the garden bed in contrast to the grass' crown of tan spikelets. The rust of sedum peeks through from behind the grass.