Plant · P-1153

Sunn Hemp

Crotalaria juncea

Sunn Hemp is a fast-growing tropical annual grown for three things from one planting: nitrogen, biomass, and a strong bast fibre stripped from the stems for twine, cord and canvas. It shoots up several feet in weeks, shading out weeds and breaking root-knot nematode cycles ahead of a following crop. The foliage makes solid protein forage, but the seeds carry a liver toxin that can poison horses and pigs, so most animals get only the boiled seed or dried, sun-cured leaf. Killed by the first light frost, it is grown as a warm-season cover crop and turned into the soil before it flowers, while the nitrogen is still fresh.