Q: We planted blackberries two years ago. There are brown branches that we feel need to be trimmed but are unsure how and when this should be done.
A: Blackberries have two kinds of branches: floricanes, which flower and produce berries, and primocanes, which will turn into floricanes next year. Your brown canes are probably floricanes, which always die after a crop is produced. Prune them out now and give each plant 1/4 cup of 10-10-10 scattered lightly around it. Fertilize again with 1/2 pound of 10-10-10 in March. This stimulates the production of new canes. Be sure to water next year if it turns dry in May before harvest. Fertilize again in June and water as needed to keep the primocanes happy during the rest of the summer.