Hot and vivid plants can look spectacular in this country, Christopher Lloyd shows this in his garden at Great Dixter.  Some thought has to be given to prevent overdoing the effect. A good analogy is when you over indulge at Christmas. Little can have a greater impact than more. Yes, you can over do it in gardens!  Foliage and their textures have a softening affect and certain colours a neutralising effect. The orange of these lilies is toned-down by the pink Salvias. What could have been gaudy has resulted in a lush display with impact.