How to Plant, Grow, and Care for Rudbeckia triloba

Rudbeckia triloba, or brown-eyed Susan, brings lively color with vibrant blooms from summer through frost. The North American native makes a sunny addition to a naturalized landscape. It attracts pollinators, and needs little tending to thrive. Gardening expert Katherine Rowe explores the merits of the easy-going wildflower with high color late in the season.

Brown-eyed Susan (Rudbeckia triloba) brings waves of sunny yellow flowers that brighten the summer and fall landscape. Cold-hardy, heat-tolerant, and rugged, the native wildflower thrives across growing conditions. R. triloba is similar to its well-known relative, black-eyed Susan (R. hirta), but is taller and has smaller flowers that emerge in profusion later in summer with a longer bloom time.

Rudbeckia triloba is low-maintenance and adapts to various conditions and soil types. Drought-tolerant once established, it needs little tending to put on a big show from July to October, depending on the climate.

Pollinators appreciate the late infusion of nectar and pollen, while songbirds forage on seeds in fall and winter. For lively color in the border, bouquet, or dried arrangement, brown-eyed Susan shakes away the weariness of late summer.


What is Rudbeckia triloba?
Rudbeckia triloba is a short-lived perennial or biennial with ray flowers. The blanket of bright yellow blooms adds color in late summer until hard frost. Common names include brown-eyed Susan, thin-leaved coneflower, and three-lobed coneflower.

The natives spend the first year developing roots and leafy growth and may produce some flowers. In the second year, full-flowering glory sweeps in before they fade. With easy reseeding, spring yields a successional crop of color.

Rucbeckia triloba is at home in the ornamental border and in native, wildflower, pollinator, rock, and cottage gardens. They’re showy en masse, which is easy to achieve with ready reseeding. They also make a vibrant addition to fresh florals that last a long time in the vase.

Brown-eyed Susan is a host plant for the silvery checkerspot butterfly (Chlosyne nycteis) and supports other pollinators and beneficial insects with their pollen and nectar. Songbirds, especially American goldfinches, forage on the seeds in the cool season.

Characteristics
Late summer and fall see a blanket of golden daisy blooms, persisting until hard frost. Multibranched stems create the all-over bloom coverage as they rise above basal leaves. Allowed to spread without other plants nearby, the bushy mounds reach four feet wide.

Each bright bloom measures one to three inches across and appears in a mass at full bloom. Short, flat, and wide, the petite flowers hold 8 to 12 rays. Black button centers fade to dark purple-brown before producing seeds and drying.

The dark green basal leaves have three divided oval lobes (hence the species name triloba). The leafy rosettes may persist through winter as an evergreen groundcover.

Cluster brown-eyed Susan with other perennials to support the tall stems in flower. They pair beautifully with ornamental grasses and with other blooms like aster, monarda, echinacea, columbine, lupine, and amsonia.

Native Area
R. triloba is native to the Midwest and Eastern regions of the U.S., from New York to Florida and west to Minnesota, Texas, and Utah. Its natural habitat is moist, open woods, fields, along streams, and on rocky slopes.

With hardiness across USDA zones 3 through 9, the perennials bear good heat and cold tolerance in wide-ranging growing situations.

Planting
The wildflowers reseed to expand the colony and fill a space given the chance. Space them 12 to 18 inches apart to allow ample air circulation while presenting a dense display of the basal leaves and multi-branched stems. In windy or shady zones, the tall stems may need support to keep from falling over. While they can reach five feet, two to three feet is more common.
How to Grow
The low-maintenance wildflowers tolerate a range of conditions and need few extra resources. They benefit from average moisture and full sun for best growth and flowering, but adapt to lesser situations.
Maintenance
Cutting back stems after flowering can extend the plant’s longevity as it doesn’t direct energy into seed production. Deadheading may also promote additional blooms and prevent unwanted seeding, too. To allow reseeding and forage for songbirds, leave blooms intact at season’s end.

Let the basal rosettes remain in place over the winter as insulation, and remove any ragged leaves in spring to make way for new growth.

Propagation

The short-lived perennials naturalize through self-seeding and propagate easily with direct sowing. Let the seeds disperse on their own, or wait at least three to four weeks after flowering to collect them. They turn dark gray when mature. Waiting a little longer makes for easier collection with looser cones.

Rudbeckia triloba benefits from cold stratification for the best germination. As seeds disperse naturally, they’ll experience a chill period in winter for emerging in spring. For indoor seed starting, store them in the refrigerator in a baggie or an airtight container in moist sand or a paper towel for one to three months. Then plant them in seedling trays.