Lupinus luteus Seeds | Yellow Lupine
LATIN NAME: Lupinus luteus
COMMON NAME: Yellow Lupine
Plant Profile
Yellow lupin is an annual legume grown for seed, for green manure and for its scent, with upright stems 40-80 cm tall and whorled yellow flowers in June. The plant is smaller and more delicate than the garden lupins, and the flowers are strongly scented, closer to wallflower than to pea.
The seed is small and hard-coated, produced in hairy pods that shatter when ripe. Yellow lupin has been grown in Europe for centuries as a sand-soil crop, and it is one of the traditional green manures of light land, sown to fix nitrogen and to suppress weeds.
The species comes from the western Mediterranean, from Portugal through Spain into Italy, and it is adapted to acid, sandy soils. That is the opposite of the white lupin’s preference, and the two are chosen according to the soil rather than the crop.
Science & Biotechnology
Yellow lupin seed carries quinolizidine alkaloids, mainly lupinine and sparteine, at higher levels than white lupin, and bitter strains are toxic to livestock. Sweet varieties have been bred for forage use, but the garden strains sold for green manure are usually bitter and should not be fed to animals without checking.
The plant’s value in a rotation is nitrogen fixation and rapid ground cover. Sown in spring, it can produce several tonnes of green matter per hectare by mid-summer, and the nitrogen it leaves behind is available to the following crop after the residues break down.
Yellow lupin is also a trap crop for some nematodes and a host for beneficial insects when left to flower. Its scent is produced by the same volatile classes found in wallflowers, and it is one of the few legumes that is worth growing for fragrance alone.
Uses & Benefits
As a garden plant, yellow lupin is sown in spring on a bed that needs nitrogen, then cut and dug in at flowering. It is also grown for the scent and for the bees, and it makes a good front-of-border annual in a wild garden.
The seed is used as a protein feed for animals after processing, and as a green manure crop in organic systems. In the kitchen it is not a garden vegetable in the way white lupin is, and the bitter strains should not be eaten. Commercially the crop is grown in northern Europe and Australia, mostly for feed.
Growing from Seed
Sow from March to May, 2 cm deep, at 15 cm apart in rows 30 cm apart. Germination is fast, seven to ten days. The seed needs moisture to start and then tolerates dry spells better than most legumes.
Yellow lupin prefers acid, sandy soil and full sun, and it will fail on chalk. Inoculate the seed if lupins have not grown on the site before. For green manure, cut at full flower and dig in within a day, before the stems become woody. For seed, let the pods ripen on the plant and harvest before they shatter, then dry the seed thoroughly.
Our Take
A useful, scented annual for poor sandy ground, worth a row for the bees and a row for the soil.
Related Reading
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