For several years, I stratified seeds in the fridge : 50% 2-3 mm aquarium sand + 50% sphagnum moss, or peat. I even tried what was suggested on a bonsai forum : soaking the seeds for 24-48 hours, discarding those that float, filter them and just put them in a zip bag without any medium. I had lots of seeds 2 years ago, I tried it, and it worked ! Just make sure the seeds are damp, but not soaked, and open the bag once in a while. I also sowed some in planters, or various pots and containers, left them outside and actually this seems the best option : less hassle and an equivalent success. In this case, I use 25% sand and the rest is a mix of what I have at hand (growing medium, akadama, ...) I also use a little hydrogen peroxide when soaking them, it's to prevent diseases. That's what my Mum used when I get back home crying, with a bleeding knee, so that must be good ;°) On some online vending sites, I saw that some species like shirasawanum and others are supposed to have a "double stratification" : 2 or 3 months warm stratif (20° or so), then 3-4 months cold stratif (3-5°C) Since I think that altenate periods of cold and waemer weather helps, I'm trying a "shortcut" : 3 weeks indoors, next to a radiator (20-22°), then 3 weeks in the fridge, then 3 weeks indoors, 3 weeks in the fridge again, then I will plant them in a planter and leave them outside. I tried it once, but I didn't have many seeds : only 3 out of 10 or so germinated, but that's not so bad, is it ?