I think he may not get the same yield that would be expected in a sunny arid area, but I would bet that Honey Jar and Bok Jo would produce at least some fruit.
A shorter, cooler summer probably makes it even more important to stay away from fruit like GA866 which seem more adapted to the SW.
I might also avoid, or at least not over-weight cultivars which tend to take a long time to produce. They could take even longer and it would be pretty frustrating not knowing if it was ever going to work for 10 years. Much better to go for something precocious, so that you get some confidence early on.
One thing which makes me more optimistic about his chances is what I saw this afternoon. I have several jujubes in partially shaded locations, even though I haven’t had especially high hopes for them. Mostly, I figured that they would get established and I would then work to make them less shaded (large tree removal, possibly involving neighbors for some).
So, today, I noticed a fairly heavy fruit-set on a Honey Jar which gets quite a lot of shade. These fruit are on the North East part of the tree (which gets the most sun).
Here’s a satellite pic, which shows the large tree to the West , the house to the North and a large Hydrangea shrub/tree close to the NW.
So, depending on time of year, the tree gets sun from mid-morning until early afternoon.
Here’s a pic which shows the large tree in the background. This pic was taken at 6:12pm, with the sun almost passing the big tree. There should be a few minutes of sun, before it gets blocked by the Hydrangea.
So, while I’ve used this as an approximation for the lower amount of sun (shorter season, lower sun angle, etc) that you would get in NH, this year has been sunnier than average, so that adds another wrinkle in.
Of course, the tree was only planted in 2020 (planted in January, which could be tough in NH, from GrowOrganic), so it is already pretty productive in year #3.
As noted above, Honey Jar is a slam dunk choice to me. My estimation of Sugar Cane’s productivity has been moving up both last year and this year. I already considered it “not bad”, but now it is getting fairly impressive.
This Sugar Cane was planted in 2017:
Closeup of Sugar Cane:
Xu Zhou is precocious and productive, but the fruit isn’t as good as the others mentioned above and also tends to crack.
Xu Zhou graft from April 2021 on tree planted in 2019:
And yes, all of these pics were taken today, and include trees from 3 different sites.
And if you are looking for a few more possibilities:
Black Sea/Russia #2
So (pretty zig-zag branches and stays smaller and wider)