How to Trim Boysenberry Bushes

Don't trim your boysenberry bushes during their first year of growth. Boysenberry plants primarily produce fruit on the 2-year old wood, so let the branches grow on the ground for the first year. Apply a layer of mulch over the plants before winter arrives to protect them from damaging cold temperatures.

Trim any weak or dead wood from your boysenberry bushes in the spring. The University of Missouri Extension recommends tying the stronger branches, called canes, to a trellis that ranges between 36 and 40 inches in height. This support helps the bush produce optimum boysenberry crops.

Prune your boysenberry bushes in the late winter after they finish producing fruit. Use bypass pruners to cut the old fruiting wood to about 1 inch above the soil line. Allow any new wood to remain on the ground. Mulch the new growth during the winter, and tie it to the trellis the following spring.

Trim your boysenberry bush in early spring. Prune out any dead or weak wood. Shorten the healthy branches to about 1 foot in length. This shorter length promotes a larger fruit size and makes it easier for you to harvest the berries.