The thing about the Goumi bush is that the berries were designed to pass through a gut system and sprout in a pile of
poop.
I've talked to five nurserymen that have never heard of anyone starting them successfully from seed here in the US. (doesn't mean it hasn't happened, just that these folks don't know about it if it has)
Every nursery I've talked with sells propagated plants only, and they all have mother plants that the cuttings come from.
It will survive up to Zone 4 and perhaps even Zone 3 with some die back or complete die back to the
roots.
Since your post got me interested in this berry bush I am now going to have to get a pair (this is a self pollinator but I like pairs of plants) once I decide where I would like them to grow.
I'll then have fruits to try to develop an easy method of germination (perhaps my hogs and donkey will like the berries so I can try that too).
Currently I would go for cuttings or already established potted plants for acquiring this gem of a bush.
Redhawk