I found the best way to propagate from seed is to plant the seed as soon as the Caper berry splits. If the seeds dry out they seem to go dormant and take a long time to germinate. If it is seed you want and you want to store it for later try to let the ants do the seed cleaning for you. I place the split caper berries in a bowl and let the ants get all over it. The ants here struggle to get the seeds up the steep sides of the bowl. They take the flesh and all you have left is a shrivelled skin and a bunch of shiny, dry seeds. Works for me!