Lupinus luteus aka Annual Yellow Lupin

Lupinus luteus, or yellow lupin, belongs to the pea family, Fabaceae. This annual comes from the western and central Mediterranean region. Its range includes Portugal, western Spain, Algeria, Morocco, and Tunisia. It is not native to Britain or Ireland. It grows in light, acid soils within its native range.

Plants form bushy clumps with upright stems and deciduous leaves. They often stand about 2 feet (0.6 metres) tall. RHS gives a garden height range of 1.6–3.3 feet (0.5–1 metre). Its listed spread covers the same range. Palmate leaves divide into as many as nine narrow leaflets. Soft, silver hairs cover the stems and leaf undersides. Upright flower spikes appear in late spring and early summer. Each holds golden-yellow blooms shaped like pea flowers. Seeds develop after the flowers fade.

Grow yellow lupin in full sun with freely draining soil. Light sandy soil or loam suits it well. Slightly acid soil is best, though neutral soil also suits it. The supplied moisture guidance spans dry to moist conditions. RHS rates it H3 for mild and coastal UK areas. PFAF lists USDA zones 5–9. These ratings use different systems and should not be treated as equivalents. Plants grow from seed and reach full size within one year. Remove spent flowers to encourage further blooms, unless saving seed.

Yellow lupin suits flower beds, gravel gardens, and informal planting. RHS also lists coastal gardens and wildflower meadows as uses. Its roots fix nitrogen, which helps improve poor soil. Growers in southern Europe use it as a green manure. For this use, prevent plants from setting seed. PFAF describes its growth as fast. Watch for lupin aphids, slugs, and snails. Powdery mildew, lupin anthracnose, and viral diseases can also occur.

The seeds have food uses, but safe processing is essential. They can contain toxic alkaloids and must not be eaten untreated. RHS warns that the plant can harm people and pets. It also advises gloves and protective gear when handling it. Properly processed, cooked seeds serve as a protein-rich food. Ground seed can be blended with cereal flour for bread. Roasted seed also serves as a coffee substitute. These uses do not make raw seeds safe to eat. PFAF records no known medicinal use for this species.