I guess I’m not sure why you are hunting the most winter hardy rootstock for NJ/Washington DC?
Either way, I don’t have any experience with Siberian C. I do have some experience with K1, and tend not to like it for a peach rootstock.
I have one Harrow Diamond peach on K1 which is surrounded by other Harrow Diamonds on seedling. The K1 is not nearly as productive overall and suffers more bud kill in the winter. On the plus side, not much pruning is required, the fruit tends to run a little bigger and sweeter, but that may have something to do with less fruit on the tree.
Well after I discovered that Nemaguard was not hardy and the krymsy 1 problems you mentioned and the fact it did not grow much. When I read it tended to produce a semi-dwarf and found a source on ebay I though why the hell not. I planned to gorilla garden the extras anyhow
Also my soil in NJ is fine but in DC its heavy clay.
I bought mine as a whip from Rolling River Nursery, I believe, in 2015. The foot tall sprout is smaller than the whip I started out with four years ago, but I leave it be as long as it is hanging in there.
My Siberian-C has had the top freeze and it resprouted several times. It is still only about a foot tall. I leave it be in its hardware cloth cylinder, but not much hope for it amounting to much, unless the climate changes a lot.
Any updates on Siberian C? I’m interested in these for fruit as they are said to be much more disease and pest resistant compared to other types of peaches and I don’t spray. I just purchased 2 trees yesterday.
thats the same guy that showed me how to over winter my figs here. great idea. i also found a Russian vid. that showed the same technique. if my contender dies to the snow line this winter that is what im going to do for the following winter…
seems like all the peaches rated to z4 arent really so. maybe just market hype but some of the nurseries that usually are conservative on zone estimates are also saying z4. time will tell. mines in a spot protected from the N.W wind so hopefully it makes it.