The advent of fall doesn't necessarily mean the end of your gardening season. Plants that flower in autumn can make your garden as brilliant as the foliage overhead. Thriving in fall's cool, crisp days and nights, these plants include colorful annuals, showy perennials and shrubs. Some of them are still going strong as late as November. Extend your garden enjoyment by using these autumn stars to replace those fading summer flowers.
Witch hazel (Hamamelis virginiana), a deciduous shrub hardy to minus 40 degrees F, grows along stream banks and in woods through much of eastern North America. Standing from 15 to 20 feet wide with a similar spread, it brightens the landscape from October to December with fragrant clusters of brilliant yellow, wrinkled blooms. Flowers may appear simultaneously with the shrub's yellow autumn foliage, but most often bloom after leaves have dropped. Pollinated plants produce greenish seedpods that ripen and persist until the following year.
The Missouri Botanical Garden recommends using witch hazel in shrub borders, as a high hedge or screening or in a woodland setting. Give it full sun (for maximum blooms) to partial shade and fertile, moist, acidic (pH below 7.0) soil. It grows well in heavy clay.
Feather celosia (Celosia argentea var. cristata), an amaranth family perennial hardy to 30 degrees F, grows as an annual where winters are cold. Reaching from 6 inches to 3 feet high and up to 2 feet wide, feather celosia begins flowering in June and continues through autumn until frost. Showy, 4- to 10-inch-dense plumes of flowers top upright stems with lance-shaped green or reddish-purple leaves. Brilliant red, orange and golden yellow blooms make eye-catching autumnal garden accents.
Plant feathered celosia in containers or group it in borders, suggests the Missouri Botanical Garden. Tolerant of partial shade, it performs best in full sun and moist, humus-rich, well-drained soil. Plants love hot, humid weather but suffer from root rot in poorly drained locations. Removing spent flowers will extend the blooming season.
Closed gentian (Gentiana andrewsii) is a North American perennial hardy to minus 40 degrees F. This plant grows wild in thickets and moist woods and near ponds and streams. Growing 1 to 2 feet high, closed gentian has 4-inch, oval green leaves and upright stems. Tightly clustered, tubular deep blue flowers that never fully open top its stems in early autumn. Use this largely pest- and disease-resistant plant, says the Missouri Botanical Garden, in rock, woodland or shade gardens. Give it partial shade and a fertile, moist, acidic, well-drained location. It needs cool nights. In ideal conditions, closed gentian will colonize.