As we all agree spring frost is one of the hardest issues with persimmons. Growing persimmons in zone 6 is no problem if it is situated in a continental type climate where spring suddenly starts from one day to the other so to speak and there is no more frost…on the other hand winter sets in just as sudden with frost from one day to the next. In a maritime climate zone 7-8 at the end of winter you will have some warm days followed by frosty days etc. and then when spring arrives this alternation may continue untill mid may. Just saying that “climate zone” does not reckon with spring frost and it is no measure that will determine if persimmon can be grown. Secondly…as I said before: heat hours is also one of the most important issues in persimmon culture. The southern part of Ukraine(5b-6a) has a very stable climate with severe frost (except for the coastal regions) and very hot summers and perfect for persimmon growing if it were not for the extreme winter temperatures. Hence the development of hybrid persimmons… The point is that accumulated heat hours during summer are sufficient for good sugar development in persimmon although the climate zone is off. On the other hand you can perfectly grow persimmons in the UK (zone 6-9), even in Scotland, but only the early varieties will have ripe fruit and it will always taste very bland because of lack of sugar. The reason being that summers are quite cool in the UK.
Persimmons don’t do well with frost. If they’re leafed out and get hit with even a light frost, all their growth is toast. Fortunately they tend to leaf out late and avoid those problems.
Agreed that leafed out would be a problem. I should clarify my above statement that I start to see some very early stage bud swell before the last frost. So they are starting to wake up when it’s frosty, but barely so. This is with the caveat that I’ve only been able to observe them over a couple of warmer than average winters…
I think sometimes they can suffer cambium damage when they’re waking up and there’s a frost. I don’t know for sure, but that seems to be why people with multiple grafts of the same variety will sometimes see a few die but a few survive just fine. I think that’s why it’s important to grow out your own rootstock if possible and select for later-to-leaf-out seedlings.
I’ll have to pay closer attention next spring. The changes I remember seeing are quite subtle. I’m confident they’re happening, but I’m less confident on the exact timing.