Sunn Hemp
Crotalaria juncea
HOW TO GROW SUNN HEMP
Direct sow after danger of last frost, dies in fall at 28˚F. Drought tolerant but there must be moisture for germination. It is day-length sensitive. August 15 is last date in Alabama for plants to grow 6 feet tall. Sowings after will bolt and not grow as tall or produce less N2. It needs zero Nitrogen but grows better with ample Phosphorus and Potash in the soil. Cut to 12–18” and allow to regrow or Incorporate after 45–60 days when about 6’ tall. If allowed to get too tall and old the stems will become tough and fibrous and not decompose rapidly and cause problems the following year preparing soil and planting. Will go to seed in Puerto Rico and Hawaii. Inoculated to improve nitrogen fixation. Soil pH 5–8.5. Hardiness zones 9–14. Annual.
Days from maturity calculated from the date of seeding. Average 430 seeds per ounce. Average 15 lb seeds per acre. There is no Federal germination standard for Sunn Hemp. Usual seed life: 4–6 years.
Planting Depth 1/2–1”
Soil Temp. Germ. 68˚F
Days to Germ. 3–7
Plant Spacing 6–9.5”
Row Spacing 6–10”
Days To Maturity 60–90
Full Sun, Moist Well Drained Soil
Days from maturity calculated from the date of seeding. Average 430 seeds per ounce. Average 15 lb seeds per acre. There is no Federal germination standard for Sunn Hemp. Usual seed life: 4–6 years.
Planting Depth 1/2–1”
Soil Temp. Germ. 68˚F
Days to Germ. 3–7
Plant Spacing 6–9.5”
Row Spacing 6–10”
Days To Maturity 60–90
Full Sun, Moist Well Drained Soil
Sunn Hemp Seed Count
.25 Pound ≈ 1,718 seeds
1 Pound ≈ 6,873 seeds
5 Pounds ≈ 34,363 seeds
- 250 Seeds$3.95
- 1/4 Pound$9.82
- 1 Pound$19.25
- 5 Pounds$96.25
Sunn Hemp bears yellow flowers and elongate, alternate leaves. It is an annual tropical legume whose claim to fame is that 60 days from planting it is typically over 6 feet (2m) tall. It adds 100 pounds of Nitrogen, it pumps from the subsoil to the topsoil 10 pounds of residual Phosphorus and 80 pounds of residua...
Sunn Hemp bears yellow flowers and elongate, alternate leaves. It is an annual tropical legume whose claim to fame is that 60 days from planting it is typically over 6 feet (2m) tall. It adds 100 pounds of Nitrogen, it pumps from the subsoil to the topsoil 10 pounds of residual Phosphorus and 80 pounds of residual Potash, supplies 4 tons of organic matter, semi-ridged stalks, increases drought tolerance and yield and cash value of the next crop. The leaves of sunn hemp are 30% protein. Grown as a green manure, livestock feed for forage, hay and for non-wood fiber, excellent for deer and goats. Strawberries, beans, tomatoes and corn benefit following Sunn Hemp. A good rotation is corn, Sunn Hemp and then wheat. Also used in rotation with sugar cane, and as a green fertilizer in the production of perennial crops such citrus, orange, mango and passion fruit. Improve soil with Sunn Hemp grown in the summer and Sodbuster radish in the fall-winter. Not industrial hemp. Sun Hemp is from the Crotalaria Genus and will not cross with the Cannabis Genus.
Weed control: Sunn Hemp does have allelopathic activity on some weeds including palmer amaranth and its very rapid growth almost totally chokes out other weeds. It can smother most if not all other weeds including pig weed, palmer amaranth, and nutsedge. Sunn Hemp is resistant to root-knot and reniform nematodes. This is another major factor for growing this crop. Root-knot and reniform nematodes are a major pest in southern agriculture. Caution: Sunn Hemp is allopathic to small seeded crops such as carrots and lettuce.
Tags: Color: Green, Specialty: Cover Crop, Specialty: Drought Tolerant, Heritage: Heirloom, Season: Summer.
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