Plant Database / Cover & Soil Crops / Sunn Hemp
Cover & Soil Crops

Sunn Hemp

Crotalaria juncea
Fabaceae (Legume)

A fast tropical legume that produces huge biomass and nitrogen in a single hot summer. Not for eating.

Cover cropFixes nitrogenBuilds soilHeat-lover
Sunn Hemp (Crotalaria juncea) illustration — Texas Roots plant database, by Jordan Polasek
Sun
Full sun
Water
Low
Soil
Tolerant
pH
5.0–7.5
Hardiness
Warm-season annual
Height
4–6 ft
Spacing
Broadcast
Days to harvest
Summer cover

What it is

Sunn Hemp (Crotalaria juncea) is in the Fabaceae (Legume) family. A fast tropical legume that produces huge biomass and nitrogen in a single hot summer. Not for eating.

How to grow it

It wants full sun, water it low, and give it tolerant soil. Target a soil pH around 5.0–7.5. Space plants about Broadcast apart. Expect roughly Summer cover. Warm-season annual.

How it's used

Sunn Hemp is used: cover crop only.

🔎 How to identify it

  • Narrow simple leaves
  • Tall slender stems
  • Yellow pea flowers

Not for eating

Grown for the garden, soil, or pollinators — not as food.
🌤 Before you plant: check the live 7-day garden weather to time it right for frost and heat.

Part of the free Texas Roots plant database, compiled by Jordan Polasek from his greenhouse in El Campo, Texas. Free to read and share. If it helped, the best thanks is to grow something.