Research on pruning has changed our thinking about this activity. There are several times during the year when it is appropriate to prune. Traditionally, pruning of deciduous plants occurs when the plant is dormant or as dormant as possible. That means, for roses and fruit trees, December and January are the months to do heavy pruning for reshaping the tree or bush and preparing for next year’s fruit or blossom crop.
However, research has shown that fruit trees can also be pruned during the summer, usually right after harvest. Rose bushes can also be pruned in the summer. If this is done, especially in roses, buds will break dormancy, and the plant will continue to grow. However, as you might guess, flower production will be curtailed for a period of time. In fruit trees there will also be some regrowth, if summer pruned, and you may need to do some “touch up” pruning in the winter.
If you prune during the summer, the wounds you make will close (seal) very quickly as the plant is actively growing and will quickly produce wound closing structures in active wood. The process of wound closure is slower when the plant is dormant. In some situations, where disease organisms are present which can attack wounds, summer pruning is recommended for the above reason. Also in California there is no summer rain, so wounds dry quickly and become resistant to pathogen attack.