Also known as joe-pye weed, this tall, native perennial can reach more than seven feet in height. "'Gateway' grows to six feet and features clouds of tiny, deep rosy-mauve flowers, which are supreme swallowtail magnets,” says Grubb.
A tender perennial, mostly used as an annual, angelonia often appears in garden centers in July. This clear white cultivar, useful for its vigor, helps keep summer gardens looking fresh. It will bloom throughout fall if deadheaded.
The smallest of the miscanthus grasses, 'Little Kitten' blooms in August and September, growing only three feet high. It does not spread aggressively. The thin, silvery grass blades have a lovely arc.
Coneflowers are a well-known medicinal plant. 'Magnus' is a tall, robust purple variety with a long bloom. ‘White Swan’ is especially lovely in drifts of five to seven plants. Its large seed heads should be left after flowers fade. Not only are the flowers attractive, but the plentiful seeds draw finches.
Grubb likes to use long-blooming annuals such as verbenas among the grasses. At first they form a low-growing carpet. Then, as summer progresses, the verbenas “snake their way through, poking their heads out here and there” in a pretty, natural way.
Gauras are long-blooming summer perennials, heedless of heat and drought. They weave delicately through grasses on their wiry stems. ‘Whirling Butterflies’ has a slight pink blush, a foil for clear whites.
This is a rare annual that needs no deadheading -- or any care at all -- to bloom all summer long. It grows tall and arcs. ‘Senorita Rosalita’ has a deep-rose color, and ‘Senorita Blanca,’ despite its name, is a subtle lavender that fades to white-pink.
Also known as Russian sage, this dependable perennial begins its blue-violet bloom in midsummer and continues into August. It craves the summer heat and is drought-tolerant.
Another tough, spiky perennial, agastache blooms long and late, and comes in many colors. This one is called ‘Blue Fortune’ and is deer-resistant.
This cultivar, ‘Snowbank,’ forms large, white mounds of tiny daisies. At five feet tall, it needs no staking and holds its own among the tallest grasses. Beloved by bees, it blooms from August through October.
Also known as the chaste tree, vitex is an underused shrub that grows six to eight feet high. As a background plant, its flowers bring a cool-blue haze to a late-summer garden.
12. Japanese Anemone
All Japanese anemones can play exquisite parts in a late-summer and fall garden. Silvery-pink ‘Robustissima’ is the first to bloom, starting in August (it also makes a great cut flower). They spread generously on runners; watch for new plants. Later in September, tall, white-flowered ‘Honorine Jobert’ will illuminate the garden into October.