I am harvesting a huge crop of blackberries this year. This evening I harvested a 9×13, level full cake pan from my small patch of Prime Jim. I am located about 20 miles north of Morris, in what is barely Zone 4. I have had my patch for at least 20 years. Soil is alkaline and fairly heavy. The reason I mention this is that searches that I have done imply that blackberries are hard to grow, especially primocaine, in Minnesota. That has not been my experience.