Lupinus perennis aka Sundial Lupine

Lupinus perennis is known as wild lupine or sundial lupine. It belongs to the bean family, Fabaceae. Its native range spans southeastern Canada and eastern and central United States. It grows in grassy places with dry, sandy soil. Habitat loss threatens wild plants in some areas. This perennial forms upright clumps and sheds its leaves. It spreads through short rhizomes and seeds.

Garden plants stand about 1–2.6 feet [0.3–0.8 metres] tall. RHS gives an upper height of 3.3 feet [1 metre]. Spread estimates differ between sources. NC State lists 0.5–1 foot [0.15–0.3 metres]. RHS gives 1.6–3.3 feet [0.5–1 metre]. Green leaves grow on long stalks. Each palmate leaf has seven to eleven leaflets. These fan out from a shared point. Their undersides have hairs, and their edges are smooth. Hairy stems may be green or tinged with red.

Flowers appear in May and June, lasting about one month. Upright racemes bear pea-shaped blooms, most often violet or blue. Some flowers mix blue with purple or white. Pink and white flowers occur less often. Bees push open the lower petals to reach the stamens. Hairy green pods follow the flowers and darken to black. Each pod holds two to seven seeds. Split pods can throw seeds several feet away.

Grow wild lupine in sun or light shade. It prefers sandy loam with good drainage. Acidic soil suits it, though it also accepts neutral soil. It tolerates poor soil and fixes nitrogen. Moderate water suits garden plants. Water during dry summer spells, as RHS advises. Cool weather supports growth; summer heat may cause dieback. Sources list USDA zones 3–9 and RHS hardiness H5. Plants may be short-lived despite their perennial habit. Remove spent flowers for more bloom, or keep them for seed.

Use it in borders, native gardens, meadows, or prairie plantings. Bees, butterflies, and hummingbirds visit the flowers. It hosts Karner blue and frosted elfin butterfly larvae. Birds and small mammals eat its seeds. Care needs are low, but pests include aphids, slugs, and snails. Diseases include powdery mildew, brown spot, anthracnose, and viruses. The plant is poisonous to people and pets. Seeds contain toxic alkaloids and pose a risk when eaten. PFAF records cooked seeds and pods as food uses. It states that seeds need thorough leaching before cooking. These records do not make untreated seeds safe to eat. PFAF also records past medicinal use of leaf tea.