Canadian County OSU Extension Service

Time to Thin Out Brambles

Do you ever wonder why those huge clumps of wild blackberries only have fruit on the outside?  All of the dead canes are hogging the space on the inside and not allowing new canes to push forth.  Once the dead canes are removed, new space will be created that allows better air flow and sunlight penetration, both of which are important for reduction of disease incidence and fruit production.

Blackberries are considered to be biennial fruiting plants. Primocanes are actively growing vegetative shoots that are produced in the first year, and the floricanes are normally the fruit-producing canes. Some erect blackberry varieties (e.g., Prime Jim, Prime Jan) produce fruit on primocanes in the fall. In the following year, primocanes mature into floricanes.

Now that the harvest is over on floricane-fruiting blackberries and raspberries, canes are on the slow decline to their demise.  October is a great time to remove spent canes because it is much easier to tell them apart from primocanes.  All canes that fruited this year should be removed (in the case of floricane (spring/summer)-fruiting varieties).  Dead canes create places for insects to overwinter as well as crowding the plant so that adequate sunlight cannot reach its interior. 

Primocane (fall)-fruiting brambles can be treated a little different.  If a cane fruited in the spring/summer, it will die and needs to be removed; however, if a cane is just fruiting for the first time in the fall it will continue to live and fruit again in the following spring/summer. The only part that will die is the part that already fruited. 

Therefore, with primocane-fruiting varieties there are two options: tip back the canes past the point where they fruited in the fall and leave the remainder of the cane to fruit next spring/summer or after the canes have fruited in the fall cut them all back down to ground level. 

If you cut them down to ground level, they will only fruit in the fall and not in the spring/summer.  Often the spring/summer crop is superior to the fall crop because the flowers are not subjected to the intense late summer heat and generally benefit from better rainfall.  Yet, who can argue with blackberries and raspberries being available up until frost in the fall?

The majority of pruning and training can be done in the winter, but removing spent canes early gives you a clearer idea of which canes no longer serve a purpose.  By keeping brambles thinned out and properly pruned fruit quality should improve, insect and diseases should decrease, and the number of delicious cobblers and pies should definitely increase.

Until next time - STOP, LOOK, and ENJOY!

~ Casey

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