Salvia and erigeron karvinskianus

I love the colour combinations you have used here. I am currently planning on enlarging my herbaceous bed, I have too many ideas, so many plants I want to use but never enough space. it is all very well for Alan Titmarsh to say you should use plants in swathes and 3 or 5 of each, and you shouldn't just have one or two of a single species - all very well if you have a garden the size of Wisley, but what if you have just an average size garden with a passion for so many different plants!? Glynis