ORGHPS Germination Guide: Sow immediately, Either the viability of these seeds is short or the species propagates best with fresh seed. Stored seed might be coaxed into germination with temperature cycling and patience. Use repeated cycles of 4°C, then 20°C for 3 months each. Germination is very prolonged. Requires soaking. Place in warm water until seeds swell, usually 24-48 hours. Discard water and any seeds that remain floating. * leave in pot for 2 years; see http://www.srgc.org.uk/bulblog/log2008/070208/log.html

Source: Ontario Rock Garden & Hardy Plant Society