How many new plants for Boysenberry hills?
I would like to start a new row of boysenberries and when tying up last years runners on support wire, I have many that have rooted on the open end. I would like to start a new row using those starts. How long should I leave the runner from the root and how many plants is best to start a new hill?
I would use two to three plants per hill. You don't need to leave much but six inches should be fine to give you a handle and provide for some amount of food to help establish the plant. Further, you can bury that cane in the ground to promote more root growth. There is this article from OSU Extension for growing blackberries (and boysenberries have similar cultural requirements.) https://catalog.extension.oregonstate.edu/ec1303