To avoid a tired-looking flower garden in September, choose to plant a few perennials that don't begin to bloom until late summer. They will freshen up the look of your garden and provide you with late summer cut-flower bouquets. In mild climates, some of these late bloomers will continue producing throughout autumn and into winter, as long as the weather permits.
Big Bluestem Ornamental Grass
A tall-growing ornamental grass, big bluestem (Andropogon gerardii) produces 4-inch-wide purplish red flowers beginning in September and persisting through February in mild climates. It grows 4 to 8 feet high with a 2-to-3-foot spread. Plant big bluestem in full sun in soil that is on the dry side. The leaves change as the season progresses. They start out a grayish blue-green in spring then turn green in summer. In autumn they turn reddish bronze with lavender tones. Big bluestem is hardy in USDA Zones 3 through 9.
A herbaceous perennial often found growing wild in fields and along roadsides, stiff goldenrod (Solidago rigida) produces bunches of tiny, half-inch yellow flowers in August and September. Although other varieties of goldenrod will grow in partial shade, stiff goldenrod prefers full sun. Plant in soil that is only moderately moist. It is hardy in USDA Zones 3 through 9.
Also called meadow saffron, autumn crocus (Colchicum spp.) produces its crocus-like flowers in late summer and early fall. The flowers are reddish-purple, lilac-pink or white and resemble the spring-growing crocus, both being members of the Liliidae botanical subclass. They grow just 6 to 8 inches high. Plant the bulbs soon after purchasing in autumn. In spring, the foliage will emerge and die back to the ground by midsummer, as is the habit of other members of the Colchicum species. The flower stems appear sans leaves in autumn. All varieties of Colchicum are poisonous.