Pruning blue elderberry
Asked July 8, 2018, 11:35 AM EDT
I planted a native blue elderberry shrub last fall. It's growing rapidly. How can I encourage it to grow into more of a tree vs. sprawling shrub shape that's blanketing widely a large planting bed? Is this even a good idea?
Blue elderberry, Sambucus caerulea, most often grows as a multi-stemed wide bushy shrub or small tree. I don't find any scientific or university articles about how to prune it into a tree form. You'll be experimenting, as I don't have a proven technique to share,.
Check out the photos in the Oregon State University Landscape Plants page for it, https://landscapeplants.oregonstate.edu/plants/sambucus-caerulea. There are a couple of photos where it looks tree-like, though always with multiple trunks. In my experience, the plant forms "canes" that tip as the top gets heavy, and weaken with age.
It grows fast and lanky, so I've usually cut back the oldest canes or trunks every few years to keep the new growth that's heavy with blooms lower. You'll find common pruning advice online, and try image searches for elderberry growth habit and tree shape. This can give you an idea of the range of shapes and sizes and is a method I've used for learning about a new plant.