NW, we are in zone 6. I have some Jostas that are 3 years old and havent seen but 2 berries and they get some wierd leaf disease that the other currants havent gotten, have seen several reports that they are dissapointing also, if mine dont put out berries this year out they go. Noursefarms.com sells a commercial variety of black currants called Titania, as well as other nurseries. So far it has done well. The smell and taste of uncooked black currants is much stronger than the fruit bases. They also have red currant bushes that make a very nice wine also.
Those dried black currant zante grape raisans do add some nice body.
Crackedcork