Summer Prune Your Blackberry Floricanes
Most blackberries have two kinds of canes, floricanes (2nd year primocanes that bear the fruit) and primocanes (first year canes that will bear next year’s fruit). The primocanes grow really tall during the summer and they should be topped off between 4–5 feet or the same height as their support structure. The removal of the growing tip will stimulate more lateral growth and increase the fruiting potential the following year. Towards the end of summer the lateral shoots can also be pruned to about 18”. If you are growing trailing blackberries (Olallie or Marion), do not tip prune the primocanes. Semi-erect blackberries can be tied up to the support. Thin to about 3–4 primocanes per plant, selecting the strongest, biggest canes. After the fruit has been picked the floricanes can be pruned down to the ground to make room for new shoots to emerge. Keep weeds removed around your plants and since berries have shallow root systems, it is better to pull them by hand. Keep a thick layer of mulch (straw works great) around the base of the plant to help conserve water and keep weeds down.