Pruning elderberries is a relatively straightforward task. During their first three years of life, elderberries should not be pruned except to remove dead or damaged limbs. However, once an elderberry bears canes more than three years old, these less-productive canes should be removed to make way for younger, more fruitful canes to grow.
Remove any dead, broken or under-producing canes from the plant at the trunk with your pruning shears.
Remove any elderberry canes that are more than three years old at the trunk with your pruning shears. The average peak production age of an elderberry shoot is two years, although some varieties still produce well at three years of age. However, canes any older than three years will not produce enough berries to warrant their energy drain on the plant and are more prone to winter damage.
Thin your elderberry if desired or necessary. Removal of elderberry canes older than three years is important to the health of the plant. However, further thinning your elderberry will encourage existing canes to be more productive.
Elderberries generally only need between six and eight canes to survive. If your elderberry is restricted by limited space, inadequate water supply or low vigor for any other reason, you may need to reduce the number of canes.
A good rule of thumb is to leave an equal number (anywhere from two to five) of one-, two- and three-year-old canes.
Trim long canes by cutting them on a diagonal with your pruning shears. This will to strengthen the plant. Plus, berries on long canes often droop to the ground or break under the weight, especially after rain.
Mulch the cuttings (this can also be done with your pruning shears) and use them to fertilize your elderberries.