Cassia occidentalis (Coffee Senna, Senna occidentalis) is a tropical legume native to the Americas, now pantropically distributed. Seeds have a hard, impermeable seed coat and exhibit physical dormancy. With proper scarification and water treatment, germination is reliable and reaches 70% or higher within 10-30 days at optimal temperatures.
Before sowing
Mechanical scarification followed by water immersion is essential. Seeds have physical dormancy with water-impermeable coats. Seeds that swell after soaking are ready to sow; non-swollen seeds require additional treatment.
Sowing
What to expect
Tips
Scarify seeds within 24 hours of planting for best viability. Sow lightly covered seeds in moist substrate and maintain high humidity with a covered container. Seeds germinate equally well in light or darkness. Optimal temperature is 25°C; germination becomes very slow below 12°C or above 30°C. Provide bottom heat if possible. Ventilate daily for 2-3 minutes to prevent fungal issues. Once seedlings emerge, reduce humidity gradually. Seedlings are ready to pot up after developing 2-3 true leaves. Acclimatize seedlings for 4-12 weeks minimum before transplanting outdoors, protecting them from first winter frost.
Sources: Scientific Reports (2020), Weed Science (2005), gardenershq.com, mediterranpiac.com, ayushvedah.com, plants.ncsu.edu, Kew Royal Botanic Gardens, Tropical Plants Database
