I can't find a single thing about growing from seed on the web so far, you might have to experiment... it may be it doesn't come true from seed, or the seed is infertile, no idea, sorry. If I find anything I'll get back to this thread

It should be a Sophora microphylla 'Sunking'. I grew my Sophra from seed. One spring I scarified the seed, soaked it for 24 hours, and if it swelled, put it in soil in a warm place. If it didn't swell, I changed the water and soaked it for another day. I kept the seed in the refrigerator for the winter. It took about 30 days to germinate.

Hi, 'Sun King' is a cultivar of S microphylla, but unlike S microphylla, is completely hardy, there are 2 ways to propagate this, 1 is to sow seed in containers , in a cold frame, as soon as it's ripe, 2 is to take semi ripe cuttings, and put them in a propagator with bottom heat, in summer or autumn, but as Bamboo says, as it's a cultivar, may not come true from seed, Derek.

Thanks for the info :o)) xx