Here's some info I dug up from the web---
Colchicum are notoriously difficult and slow to grow from seeds because the seeds will not sprout without summer heat treatment and a cool down period during the autumn. Diana Chapman provided the following valuable tips for successful germination. Seeds should be sown fresh in a well-drained mix, covered with one of two cm of grit or course sand. Keep the mix slightly moist during the warm days of the summer. It is best to leave the seeds outdoors where they can experience the summer heat and fluctuations in temperature. In the fall, water well and allow the seeds to germinate. Some species may take two years to germinate so keep your pots for at least 2 years. Sporadic germination had been observed by gardeners after many years. Some growers have good success with soaking the seeds 1-2 days before sowing. This can be done by simply soaking in a bowl of water or placing the seeds in a stocking, tie the end and placed into a toilet bowl (water reservoir). Every flushing will wash away the inhibitors and allows the seeds to germinate.
The paper "Effects of Stratification, Temperature and Light On Seed Germination of Colchicum Macrophyllum B. L. Burtt", by Anna Antonidaki-Giatromanolaki, Magdalena Dragassaki, Michael Papadimitriou, and Ioannis Vlah, Vol. 8, № 2, 2008: 105-107, Propagation of Ornamental Plants, concludes that the seeds need a warm moist period (eight weeks at 20 °C) followed by a move to cooler temperatures (10-15 °C) and darkness for germination.
