Lupinus rubens Seeds | Red Lupine
LATIN NAME: Lupinus rubens
COMMON NAME: Red Lupine
Plant Profile
Red lupin is the red-flowered garden lupin, a short-lived perennial 60-100 cm tall with palmate leaves and dense spikes of pea flowers in shades from brick to deep crimson. It is grown in the same way as the blue and pink Russell hybrids, and it flowers in late May and June.
The plants die back to a crown each winter and regrow in spring, and they are at their best for three or four years before the crown goes woody and the flowering thins. Seed is the easy way to keep a stock going, since the plants self-sow in light soil.
The red-flowered lupins in gardens descend mainly from Lupinus polyphyllus of western North America, crossed with other species in the nineteenth and twentieth centuries. The name Lupinus rubens is used in the trade for red forms, though it is not a species in the current botanical sense.
Science & Biotechnology
The colour range in garden lupins comes from a small number of anthocyanin and carotenoid combinations, and the reds are the hardest to fix. Seed from a red parent gives a spread of reds, pinks and purples, which is why named clones are propagated from cuttings rather than seed.
Lupins fix nitrogen through root nodules and are useful in poor acid soils for that reason. They also produce quinolizidine alkaloids, which make the seed bitter and toxic to grazing animals, and the foliage is avoided by deer and rabbits for the same reason.
The genus has a long history in plant genetics. Lupinus was among the plants used to study the inheritance of flower colour and of the inflorescence form, and the garden hybrids show that history in their unpredictable segregation.
Uses & Benefits
Red lupins are border plants for the gap between spring bulbs and the main summer show, and they are one of the few tall perennials that will grow in poor acid soil. They suit cottage gardens, woodland edges and the back of a mixed border, and they combine well with alliums and geraniums.
Cut spikes last four or five days and are useful for a large vase. The seed is bitter and should not be eaten, though sweet white lupins are a different crop altogether. In the garden the plants are useful for holding sandy banks, where their taproots stabilise the soil.
Growing from Seed
Sow in spring at 15-18°C, 1 cm deep, after soaking the seed for a few hours or nicking the coat with a knife. Germination in ten days to three weeks. Sow direct where they are to flower if possible, since the taproot resents disturbance.
Plant out at 40 cm apart in full sun or light shade, in acid to neutral soil that drains. Water through the first summer and mulch to keep the roots cool. Deadhead the first flush to encourage a second, lighter one, but leave a few spikes to set seed if you want the colony to renew. Cut the old foliage to the ground in autumn and watch for slugs on the new shoots in spring.
Our Take
A red that works in a wilder border, cheap from seed and generous for three or four years before it needs replacing.
Related Reading
Gardeners who grow Red Lupine often pair it with these related subjects: