Anne-Marie:
The subject of germinating Colchicum seeds has driven even the most hardened bulbophiles to the point of extinction or at least hair puling.
You can have a look at the Scottish Rock Garden Club or any of the other horticultural specialty groups and they all say the same thing, Good Luck.
From my research and a bit of common sense it seems the seeds need a warm period just after they are collected. The theory is that the seeds are not yet fully ripe at time of dispersal and require some warm temps to ripen. Just think about what the temps and moisture availability are where they grow.
Arnold
New Jersey
: From same seed exchange I got a pack of colchicum speciosum seed.