Sometimes I think the seed bought commercially is old and has lost a lot of its vitality. If you can find someone with fresh seed I think you will be ahead of the crowd.

Back when I was growing tuberous from seed, the germination rate was abyssmal. Same for gloxinia. Then I sowed some seed from one of my store bought gloxinias and the germnation rate was so high that the surface looked like moss. When it was about knee high to the proverbial grasshopper I knocked the cup over and lost them all - so this is just another thing to watch out for.

Anyway, here are a couple of sites for growing begonias from seed (I would think tuberous would be very similar).

Hope this helps:

ABSASTRO site

Brad's World

Thanks for the info. Sorry to hear about your gloxinia troubles. I had so much germination in '87, with a mix from Park's, that I had to give away seedlings. Currently, I only have one discounted store Sinningia -- a white/blue -- that I own. They're not favorites of mine, since their requirements are too greenhouse exacting. Received a replacement packet of the 'Show Angels' begonia, and planted them today, rather than wait till early '09 to try. Hoping for better results! Thanks again.