Several pruning methods work for Sambucus nigra. The method that works best for you depends on whether you grow the shrub for fruit, for flower production or strictly as an ornamental shrub. Pruning an elderberry bush to the ground yearly in early spring causes the plant to produce up to 20 percent more fruit than any other pruning method. This method is known as rejuvenation pruning. If you wish to obtain enough fruit to use, you can opt to prune the shrub selectively instead and still induce an increased fruit yield, although it won’t be quite as high of a percentage increase as the rejuvenation pruning method produces. Selective pruning involves the removal of specific branches, such as non-bearing branches or branches that grow where you do not want them. Always use pruners that are clean and sharp, remove the dead wood first and make smooth cuts at a 45-degree angle.
Bushiness or Shape
Selectively pruning a Sambucus nigra to encourage bushiness can prevent damage to the branches from high wind, heavy snow and ice. It also is a way to control the mature size or shape of the plant. Regular pruning prevents the branches from becoming too long and gives you the opportunity to grow a larger plant in a smaller space as long as adequate room is underground for the roots to grow. Shorter branches withstand snow, ice, heavy rain and high wind better than longer branches. Birds and other wildlife also appreciate bushier plants because it gives them a place to hide from predators and to nest.
Creating a shrub with a specific shape is another reason for selectively pruning an elderberry. Whether you want a smaller shrub, one that is square, rounded or another shape altogether, selectively pruning is the way to accomplish the project.
Removal of older wood allows more sunlight to reach the Sambucus nigra's interior branches. More sunlight encourages more flower production along the branches instead of just at the top of the plant where sunlight reaches easily. Sambucus nigra flowers during summer months; so once growth commences in spring, pruning can remove some of the flower buds, which is not always bad. The shrub expends a lot of energy to produce masses of flowers. Selectively pruning the elderberry to remove some of the forming flower buds can result in larger flowers that reach maturity.
Pest and Disease Control
A number of diseases affect Sambucus nigra, including canker, powdery mildew, dieback, rust, fungal leaf spots and various viral diseases. Additionally, elderberry shrubs are prone to attack from spider mites, aphids and borers. Rejuvenation pruning can eliminate a lot of those problems, but so can selectively pruning. It is important, for the health of your elderberry, that air can circulate around the branches and that sunlight can reach the plant's interior. Remove older wood that is non-productive as well as branches that have signs of pest infestation or disease. Also remove branches that cross over one another. Removing all dead, weak and broken branches is wise because they are an invitation to pests and disease. Eliminating the potential causes before pests or disease have a chance to take hold is the best way to ensure your Sambucus nigra continues to thrive.