Rudbeckia triloba aka Brown Eyed Susan

Rudbeckia triloba has two common names: brown-eyed Susan and three-leaved coneflower. It belongs to Asteraceae, the daisy family. Its native range spans eastern Canada and the United States. It may live as a biennial, or two-year plant. It may also live as a short-lived perennial. It forms upright clumps with a bushy shape. New plants can grow from seed when older plants die.

Sources give garden heights of 1.6–5 feet [0.5–1.5 metres]. North Carolina State gives a typical height of 3–5 feet [0.9–1.5 metres]. Chicago gives a shorter range of 3–4 feet [0.9–1.2 metres]. Reported spread ranges from 1–3.3 feet [0.3–1 metre]. Thin, hairy stems branch well and may have a red tint. Rough green leaves grow in turns along the stems. Their edges have teeth, and leaves often have three lobes. Leaves at the base form a ring called a rosette. This can last through winter. The plant sheds its other leaves as the seasons change.

Yellow flowerheads bloom from July to October, based on location. Each head has rays around a dark brown central disk. The raised centres form cones, and the rays bend back. Upper stems bear one or two heads at their tips. Bees and butterflies get nectar and pollen from the flowers. Silvery checkerspot and wavy-lined emerald larvae use the leaves as hosts. Fruit forms from August to November. Songbirds eat the seeds in fall, including American goldfinches.

Grow this plant in full sun for a strong upright shape. It can grow in light shade, though stems may need support. It prefers moist soil that drains well. It grows in clay and loam. The soil can be acid, neutral, or alkaline. Once growing, it copes with heat and some drought. Chicago lists USDA zones 4–8, while RHS gives H6 hardiness. Plants reach full size in one to two years. Grow them from seed, or plant seedlings once frost danger passes. Remove spent heads to help extend bloom and limit unwanted seedlings. RHS advises cutting plants back in late autumn.

Use it in borders, meadows, prairie plantings, and informal gardens. The flowers suit cutting and gardens for wildlife, too. It needs little care, but self-seeding can make it somewhat weedy. Deer tend to leave it alone, though they may still browse it. Serious pests and diseases rarely cause problems. Powdery mildew can occur. Slugs or snails may harm young plants. The supplied sources give no clear food use. They also give no clear assessment of toxicity.