Hi, my boysenberry and blackberry bushes are running rampant. Should I cut them back in autumn?

Hi Lyn, the best time is after fruiting. Boysenberries fruit on two year old wood. Remove any canes that have fruited as they die back, leave the new canes as they will be next seasons crop. Remove tips to encourage lateral growth.

With blackberries new seasons growth is vegetative, if also fruits on two year old growth. Remove any old fruiting canes, weak or dead canes. Remove growing tips to encourage lateral growth and more fruit.