Astrantia seeds require a period of moisture and cold to germinate and are easiest sown into pots in late autumn and left outside over winter for spring germination. Alternatively, in spring, surface-sow onto moist, well-drained compost and moved to a cool location, such as a cold frame, for 4 weeks at around 39°F (4°C). Later sowings can be artificially stimulated by covering them with a polythene bag and placing in a refrigerator. Return to warmth at 64-71°F (18-22°C). Germination can take many months. Transplant seedlings once large enough to handle into individual pots and grow on, hardening off for 2 weeks before planting out.