Today I finally dug up my oca.
As we had severe frost this winter (-15, which is rather rare in the Netherlands) and for quite some time, I thought my oca would be mush.
There were a few tubers damaged by frost, but I dug out about two kilos that were okay.
Saddad send me a handful last spring, about 10 tubers, so they produced well.
Thanks saddad :-*.