The RHS journal, "The Garden", had a squib many years ago on work done at Kew regarding germination of Alstroemeria that is worth tracking down. It would be in the 1980s or 1990s, but I can't give a more precise citation without burrowing through the journal issues one by one. IIRC, it involved dissecting out part of the seed body that conceals the embryo, then stratification in more than one stage, but my memory isn't good enough to cough up all the details with accuracy. If someone finds this article, would the RHS allow the PBS to include the text on its wiki?