csandt, that is going to be gorgeous! I do the same thing with the cardboard, gets rid of a lot of the weeds and attracts earthworms at the same time--win, win! I'm going to look for some butterfly bushes that aren't supposed to get too big and add them this fall. Wonderful ideas and love the gardens!
Tracey, I really never considered planting annuals, even putting out zinnia seed, but that would absolutely add so color later in the season. And that would solve the problem of late blooming perennials getting too big and crowding everything else.
