Fill Summer Flower Beds With Annual Rudbeckias

Posted by Hugh on July 10th, 2018

Rudbeckia hirta ‘Tiger Eyes’ at NC Arboretum in Asheville

‘Indian Summer’ rudbeckia in Pittsburgh, PA

Black-eyed Susan (Rudbeckia hirta) is a native wildflower. Annual or biennial forms are also called gloriosa daisy and brown-eyed Susan. In recent years public urban gardens are growing annual types. From summer into early autumn, brown-eyed Susans produce showy daisy-like blossoms up to 3-inches across with light or deep yellow rays and brownish-purple centers (“buttons”). Their cut flowers will decorate households.

This coarse weedy plant has undergone a breeding improvements. Today’s varieties bloom most of the summer and with disease-resistant leaves. Colorful ray flowers are available in shades of red, yellow, bronze, orange and bi-colors. They bloom non-stop through the summer atop sturdy upright stems. Plant heights vary by cultivar from 1-3 feet high. Rough, hairy, lance-shaped leaves are 3-7 inches long.

This biennial or short-lived perennial is winter hardy to USDA Zones 3-7. It blooms the first year from seed set out in early spring. It grows in average, moist, well-drained soils and in full sun. Brown-eyed Susan is at its finest in moist, compost-rich soils. For maximum bloom time, start seed indoors in late February or the beginning of March. Garden centers sell them in cell/six packs. Set out seedlings or purchased plants after the last frost date has passed. At planting time feed the flower bed with a granulated fertilizer such as 10-10-10 or or equivalent plus a secondary feeding in early summer. Deadhead spend flowers to encourage lateral branching and additional bloom. Removing old spent flowers also prevents self-seeding.

Most disease and pest problems may be avoided if properly sited and care for. In some years aphids, rust, powdery mildew, and septoria leaf spots may trouble these annuals. Watch for slugs and snails on young plants.