Bigleaf lupine
Also known as
Large-leaved lupine, Garden lupin, Big-leaved lupine, Large-leaf lupine
Keep this plant’s care guide close at hand.
Get the appAbout Bigleaf lupine
Lupinus polyphyllus, commonly known as bigleaf lupine, is a herbaceous, short-lived perennial in the legume family. It forms basal clumps of palmately divided leaves with 9–17 silky leaflets that shed water. In late spring to early summer it sends up stately, densely flowered racemes 60–120 cm tall in shades of blue, purple, pink, white, and bicolors, often visited by bees and hummingbirds. A deep, brittle taproot anchors the plant and hosts nitrogen-fixing Rhizobium, allowing it to thrive in relatively poor, sandy or loamy soils. The plant is hardy in cool, temperate climates and prefers moist but well-drained sites; prolonged heat and humidity reduce vigor. Seed pods follow bloom and can eject seeds, leading to self-sowing; in some regions it has escaped cultivation and become invasive. Plants resent root disturbance and may persist only 3–5 years, but can be renewed from seed or basal cuttings. Its bold foliage and vertical bloom spikes make it a classic feature of cottage gardens, meadow plantings, and pollinator borders.
Taxonomy
Properties & Requirements
How to care for Bigleaf lupine
Water
Keep soil evenly moist during establishment and bud formation, watering deeply once or twice weekly depending on rainfall and soil type. Aim to wet the root zone 15–20 cm deep, then allow the top few centimeters to dry slightly between waterings. Avoid overhead irrigation in the evening, which encourages mildew; use soaker hoses or drip at the soil line. Once established, plants tolerate short dry spells but flower best with consistent moisture. Never let them sit in waterlogged soil.
Light
Provide full sun in cool, northern or maritime climates (6–8+ hours daily) for the strongest stems and most flowers. In regions with hot afternoons, site in bright morning sun with light dappled shade after 2 p.m. Too much shade leads to lanky growth, fewer blooms, and higher mildew risk. Avoid reflected heat from walls or pavement. Maintain open air circulation around plants to keep foliage dry and healthy while still giving them ample light.
Nutrients
Being a nitrogen-fixing legume, bigleaf lupine needs minimal fertilizer. Work in 2–5 cm of compost in early spring and avoid high-nitrogen products, which suppress nodulation and yield lush foliage with fewer blooms. In poor soils, use a low-N, phosphorus- and potassium-leaning organic feed (e.g., 3-4-4) at half strength once in mid-spring and again after the first flush to support roots and rebloom. If planting in sterile or new beds, inoculate seed or roots with Rhizobium lupini for best performance.
Temperature
Hardy in USDA Zones 4–8, bigleaf lupine thrives in cool summers and cold winters. Ideal growing temperatures are 10–24°C (50–75°F). Heat above ~30°C (86°F), especially with high humidity, can shorten bloom and stress plants; provide afternoon shade and extra water in hot spells. Winter-hardy to at least −34°C (−30°F) when well rooted and mulched. Avoid planting in persistently hot, humid climates where disease pressure increases and longevity drops.
