Propagation:

Division in spring.

Seed – needs cold stratification, best sown in September - November.

Seed just covered and stored for 2-4 weeks at 22°C (72°F) and then it‘s moved outside until germination. Germination can be slow, seed may germinate a year later, so it‘s important not to throw it away prematurely. Optimum germination temperature is 18°C (64°F) so it‘s best to move it inside in spring.

Another possibility is to store the seed tray in the refrigerator for 4-6 weeks and then move it to 18°C.