
Bloom time in most American perennial borders runs from late May through early July—a glorious but short 5 or 6 weeks. By late July, most perennial gardens are past their prime and look pretty dull for the rest of the season.
Fortunately, there are many perennials that bloom in late summer, including coneflower, asters, mums, Russian sage, cimicifuga, sedum, rudbeckia, and phlox. But I've found annuals are the real key to summer-long color.
Unlike many perennials, most annuals thrive in summer's heat and once they get started, will keep blooming right into early fall. With a little planning you can create annual - perennial partnerships that will keep your flowers gardens looking terrific for a full 5 o 6 months.
There a are few perennials that save their big show for the end of the summer, and remember impatients bloom until frost, and the the coleus have incredibles colors to choose from.