[header] How to prune blackberries [title] Prune part of the stem. [step] When planting a blackberry vine as a rooted cutting, prune off two-thirds to three-fourths of the handle or stem, leaving only a short crown behind. Doing so stimulates the buds at the crown of the cutting, encouraging them to grow more vigorously. 
[substeps] The " crown " of the cutting refers to the portion of the cutting that extends just above ground once the cutting is planted. Cutting off most of the stem also removes any potentially damaged or diseased tissue that may have been on the stem.