Interesting post, thanks for sharing experiences, everyone!
I'm looking at growing Jujubes in Latvia, Northeast Europe, but I think it might be just too cold, with not enough summer heat.
We are at USDA Zone 5B here (lows to -15°F or -26°C) & a nursery from Poland where winters are warmer states the bush may need covering in cold winters. See:
https://kielkowski-szkolka.pl/produkt/glozyna-pospolita-tzw--daktyle-chinskie----ziziphus-jujuba--204
On the other hand, I saw a nursery in Canada saying that Jujubes are hardy to -25°C and can be grown in a pot and brought into a garage in colder climates. See:
https://www.greenbarnnursery.ca/products/ponderosa
Of course summer ripening is another issue - here we only have 3-4 frost-free months, frosts can easily return by the end of September some years.
I would love to hear more from your experiences guys, as this post is already a couple of years old - did they grow for you?
Thanks to all for sharing precious knowledge & experience, it really helps!
Charlie