Update to my compilation of “Persimmon Cold Hardiness Resource”:
My south central Kansas location has had 2 years of drought stress, so I will say that some of my losses could be from a combination of drought stress and cold, but some of the trees I had in the 6a category, I would move down a zone to 6b, and I would for sure lean on the side of a half a zone of caution and focus on planting the ones in the 6a list in your 6b location, etc…
Here are suggestions:
For zone 6a, usda2012, your very best options on hybrids are:
Jt-02. -20 to -25F?
JBT-06. -20 to -25F?
Chuchupaka. -16 to -20?
Nb-02. -16 to -22F.
Some of these may work in a very sheltered microclimate of 5b…
A few others may work for a sheltered location in 6a, but i would focus on those above…
And as well they are the best for 6b too, lean on the side of caution if you can, and some others great for 6b if your location is not too exposed, are probably:
Rosseyanka. -18 to -22?
Kasandra. -17?
Sosnovskaya. -12 to -18?
Pamjat Pasenkova. -10 to -16F?
If you have a really sheltered southern 6b (usda2012) location, or established rootstock and less stressful climate than me, like out east in a nice Virginia Valley or something, others on my original list for 6a or 6b may work and my original list may be more perfect for you since others have gotten those results and success… Here in Kansas we have Prairie Windchill, little protection, drought stress, and in short The Wizzard of OZ!
I recommend first planting 90c/or northern sourced American Rootstock, grow them out 2 or 3 years, at least 1/3" thick seedlings, hopefully 2/3", before trying to graft, then when you spring graft, that established rootstock will supply energy for fast growth before winter. In a marginal situation, a thicker limb will take a lot more cold than a small grafted twig. I have had small 6" established grafts freeze off in mild winters, when a well established 3 year old plant took 10 degrees more cold in a polar blast with no damage at all!
Sheltered microclimate means a lot! For instance, one of my Che varieties at our upland prarie homestead all three established grafts totally froze out in a cold blast winter, but 6 miles down the road at my orchard which is a valley with hill and tree wind protection, that same Che variety recieved no damage at all… Yet variety matters, at the homestead several grafts of a different Che variety recieved no damage at all right next to the ones that were all killed…
Both locations are in the middle of 6b usda2012.
At my protected valley location, Davids Kandy has recieved lots of damage 2 out of 4 years, and Sovietski I grew a big 5ft potted tree before planting out there, the first winter inground it was killed to just above the graft, but did a lot of regrowth, then the second winter it was killed, yet a similarly established Kasandra and NB-02 nearby has never even had twig damage all of those same winters… So yeah some of it could be from summer drought stress and i would have more confidence in a Virginia 6b than here in kansas, but yes anyway, it is a test, as the Kansas Moto says “To the Stars with difficulty”. And as Trump said, “Never give up, if theres a brick wall go through it…” i just refuse to give up… but for those wanting just a few trees, go with those sure ones, and establish your rootstock first I recommend. Or else just plant tough stuff like the Romance Cherries lol 