How to germinate Crotalaria spectabilis

Crotalaria spectabilis is a tropical annual legume native to Asia, commonly known as Showy Rattlebox. Named for the rattling sound seeds make in mature pods. Contains monocrotaline alkaloid toxic to livestock. Used historically as nitrogen-fixing green manure crop.

Before sowing

Scarification

quimica Seeds have hard seed coat (physical dormancy); chemical scarification with 80°C hot water for 2 minutes is effective; mechanical scarification also recommended due to high percentage of hard seed

Soak

12 h Pre-soaking seed for 12 hours in warm water reduces germination time; heat treatment (80°C water) plus hydration-dehydration cycle effective

Seed coat impermeability requires treatment; scarification is critical due to seed dormancy; combination of heat and hydration-dehydration most effective

Sowing

Substrate

sandy soil, well-drained soil, loam

Depth

0_5cm

Temperature

25°C

Moisture

media

What to expect

Step 1

Pre-treat the seed

Step 2

Sow at 0_5cm · 25°C

Day 3–7

Seedlings emerge (~47%)

Tips

Grows best in full sun and warm temperatures. Summer annual in continental US. Scarification essential for germination. Dormant seeds may germinate after dry storage at 23°C. Sow 3/4 inch depth. Seedlings emerge quickly and form dense cover. Can reach 50-150 cm height.

Sources: Egley 1979 (Weed Science), Tropical Plants Database, UC Davis SAREP, ResearchGate study on combined scarification treatments, NC State Extension, USDA PLANTS Database, Useful Tropical Plants Database

Fresh seeds to sow

Crotalaria spectabilis

Before sowing

Sowing

What to expect

Tips

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