Andean Lupin

Lupinus mutabilis, known as tarwi or Andean lupin, is a large-seeded edible lupin native to the Andes of South America where it has been cultivated as a staple protein crop for millennia. The seeds are flat, white, and exceptionally high in protein and oil. It forms an upright, bushy plant with attractive blue-purple flower spikes and improves soil fertility through nitrogen fixation. It performs best in well-drained, slightly acidic, sandy or loamy soils in a warm, sheltered position.

Growing

Start seeds indoors in trays once nights stay reliably above 8 °C, sowing 2 cm deep. Germination takes 10–21 days at soil temperatures of 10 °C or above. Grow on until seedlings reach approximately 5 cm tall (roughly 4 weeks). Transplant outdoors at 20 cm diagonal spacings only after all frost risk has passed and air temperatures remain consistently above 8 °C at night. Lupins dislike root disturbance, so transplant carefully with minimal root interference.

Care

Water regularly but avoid waterlogging — Andean lupins tolerate moderate drought once established. Do not over-fertilise with nitrogen; as a legume it fixes its own. Support tall plants with canes or netting in exposed positions. Remove spent flower spikes to encourage continued pod development. Mulch around the base to retain moisture and suppress weeds.

Harvest

Harvest pods when they have turned yellow-brown and feel papery but before they split open and scatter seeds. Pick pods progressively as they ripen over a period of about three weeks. Shell the beans and spread on trays to dry fully before any further processing. Fresh beans require soaking and repeated water changes to remove bitter alkaloids before consumption.

In the kitchen

Dried tarwi beans must be soaked in water for 12–24 hours and then boiled and repeatedly rinsed over 3–5 days to leach out bitter lupine alkaloids. Once detoxified, the cooked beans have a firm, creamy texture and nutty flavour. Use them in stews, salads, ceviche-style dishes, or purée into dips. The protein-rich flour ground from dried beans can supplement wheat flour in breads and flatbreads.

Storing

Store fully dried seeds in an airtight container in a cool, dark, dry place for up to 2 years. Cooked, detoxified beans keep in the refrigerator for up to 5 days or can be frozen for up to 6 months. Do not store beans that have not been fully detoxified, as they remain bitter and mildly toxic.