Blackberries grow new canes every season, producing berries on the previous year's growth. First-year canes are called primocanes and second-year canes are called floricanes. The floricanes die after fruiting and need to be removed. Dead canes spread disease and, if left untrimmed, they eventually create an unsightly, tangled mess. First-year blackberry plants need very little pruning; begin trimming during the second year.
Trim away the top 1 to 2 inches when the plant reaches 3 feet tall. This trimming will encourage branching and a larger harvest next year. Use pruning shears to snip off the top of the new growth.
Remove wilted and dying canes during flowering and fruiting. Winter damage becomes evident at this time and cane blight can quickly take hold. Use clean pruning shears to cut the damaged and diseased canes all the way back to the trunk.
Remove fruiting canes as soon as the harvest is over. Trim back to the trunk.
Clean under the vines, removing dead debris. Burn removed canes.
Trim fruiting canes back to the trunk as soon as the harvest is over.
Thin out the new growth, leaving 6 to 12 of the strongest new canes for next year's crop. Allow these canes to remain on the ground, covered with mulch during their first winter.
Lift onto the trellis in the spring of the second year after the danger of frost is past. Weave the canes around the trellis to hold them up. Remove all wilted and dying canes.
Trim the shorter canes and any broken or kinked canes back to about 8 to 10 inches. Remove all canes on the bottom 18 inches of the trunk, cutting back to the trunk.
Clean all debris under the vines. Burn trimmed canes to prevent spread of disease.
About this Author
Diane Watkins has been writing since 1984, with experience in newspaper, newsletter and web content. She writes two electronic newsletters and content around the web. Watkins has a Bachelor of Science degree in chemistry from Clemson University. She has taken graduate courses in biochemistry and education.