Canna Indica Germination:
1) Scarify the seed by rubbing with sandpaper aggressively, and use a small knife to put a few "shallow" nicks into the hard shell. (Not too deep)
2) Pour hot water over the seeds and let them soak for 24 hours. If seeds are not swelled, make a few more shallow nicks and soak in warm water for 24 more hours.
3) Sow seeds 1 1/2" inches deep in a well mixed, well draining seed starting mix. 
4) As with any tropical or exotic seed, patience is required as germination will be erratic with some sprouting within 3 weeks, while most others will take all the way up to 9 weeks to sprout. Definitely Worth the Wait!