Dear All, I also have made the experience that some Tropaeolum tubers just do not sprout although they are firm and healthy. I grow mine in pots in a frost free greenhouse and keep the almost dry pots under the staging during the summer dormancy. T. tricolorum is very reliable and will sprout every autumn but I have a pot of T. brachyceras that grew for several years but now is dormant I think in its third year. I checked the pot in autumn and found a rock hard healthy tuber without any signs of desiccation nor damage but it just does not sprout. I do not know the reason. There are also two pots of South African Ornitohgalums that have even flowered with me but now they have that same kind of dormancy with firm bulbs that are doing their second season of un-breakable dormancy.......Hmmmmmm. Any advice on how to talk them into growth? Greetings from cold and wet AND DARK Germany..... and best wishes for Christmas Uli