Sunn Hemp - Key Growing Information
Uses: A warm-season legume that produces huge amounts of biomass and fixes nitrogen. It handles heat and drought and grows in tough soils.
Culture: Sow ½–1" deep once the soil has warmed to 65°F (18°C). Sunn hemp doesn't compete well with weeds, so it's best grown with vigorous warm-season grasses such as sudangrass or millet. For the most growth and nitrogen fixation, inoculate with a sunn hemp/cowpea inoculant. It performs well in drought and in low-fertility soil.
Seeding Rate: Alone: 1 lb. per 1,000 sq. ft. or 30–50 lb. per acre. In a mix: ¼ lb. per 1,000 sq. ft. or 4–8 lb. per acre.
Light Requirements: Full sun to part shade.
Soil Requirements: Grows in most soils.
Height: 48"+
Harvest: Can be grazed up to flowering.
Caution: The flowers and seeds can be toxic to livestock.
Termination: Because it's so tall and stemmy, sunn hemp can be hard to handle without bigger equipment. Mowing it close kills it well, especially if followed by tillage. It doesn't survive frost, so it winter-kills reliably.
