Caroline - I too have that problem so I plant about 6 of the little annual Begonias (I like the dark leaves and white blooms) and a couple of colourful Gerbera Daisies. I have a Daylily, Early Bird Cardinal, that blooms first of all my Daylilies and I noticed the other day that it is forming buds once again (Sept). I have a Rose Mallow Hibiscus with gorgeous large red blooms in late Aug. and early Sept. I also have Tickseed Coreopsis Presto which is still blooming somewhat as well as 2 Neon Pink and 1 Autumn Joy Sedums, and New Snow (Snow Cap). I also have a Mum but it usually doesn't get around to blooming before it snows for some reason although perhaps this year as we are to get a warmer than usual fall they say. I also like to plant some things with different coloured leaves - different shades of green and some reds (like Palace purple Coral Bells, and Japanese Blood Grass). Some of my ground covers are varying colours as well - one, Golden Sedum/Stonecrop Orpin Angelina, is orange in the spring and fall. For summer colour, I have a yellow and a red Stella type daylily, 3 taller type daylilies, 2 kinds of Shasta Daisies, 2 miniature roses and several ground covers (spring/summer for those). Hope that was helpful.
