Ingenuity and perseverance, Robert. With a pocketful of nicked seed pods I could hardly ask the Head Gardener at Wisley for his advice on sowing, so I sowed a few seeds in each of about 2 dozen small pots and subjected them all to varying periods of warm greenhouse, refrigerator, warm greenhouse in that order. I used a 3:1 peat/sand compost with Chempak seed base. I know that only one pot produced seedlings, but I`m afraid that after 45 years I certainly can`t remember what precise treatment it had.
Never fear, there`ll be enough seed for you to do as I did, but you`ll have to let me know where to send it when it`s ready