Photo courtesy of Creative Commons.
Sunn Hemp (Crotalaria juncea) is a poplar nitrogen-boosting member of the legume family. Although notably grown in the more tropical regions of Asia, it actually originates from India. It is perfect for the home gardener or an urban farm because of it’s soil-improvement qualities (if adequate growing space is available). Wildlife areas and livestock farms also benefit from its status as as forage or fodder (if consumed in the early stages of growth; it becomes fibrous as it matures).
Commonly known as a “green manure”, Sunn Hemp is grown in the agricultural community as a cover crop to help improve soil health and combat problems such as weeds, low nitrogen and soil erosion. Sunn Hemp is also resistant to nematodes like soybean cyst/root knot, making it a safe and organic means of pest control.
Technically grown as an annual in the US, this fast-growing plant needs up to 60 days of consistent, warm temperatures to reach optimum growth because of its nature. It generally takes 60-90 days to harvest depending on your growing zone. It prefers well-draining sandy soil and generally does not require general fertilizer (it would however benefit greatly from soil that is rich in phosphorus and potash). After sufficient growth, Sunn Hemp is generally drought tolerant and it reaches an impressive height of 6 to 7 feet, making it an eye-catching addition to gardens large or small.
Garden Variety 
As effective as it might be, the name would keep me from growing it; or if I did, I would refer to it as some sort of vetch.
Good
Thank you 🙂