Subshrubs are plants that possess traits of both woody and herbaceous plants. When it comes to pruning, however, it’s a good idea not to cut them back to the ground since this can result in the removal of their growing points and can ultimately lead to their demise. Depending on the type of subshrub, the best times to prune are in the spring and, in some cases, after the first bloom. During the cooler seasons, limit your pruning to the removal of spent blossoms and dead branches and avoid cutting into live woody stems. Cutting back plant material will promote a growth response. Continue reading how to do that in the source.