Rejuvenating a shrub is the process of removing old stems to reduce the plant’s size and increase its vigor. Reduction, in contrast, means removing just a few large stems to reduce the plant’s size. To rejuvenate a shrub, you remove about a third of the stems each year for three years. Most shrubs require rejuvenation at some point, as they outgrow their space or become leggy. Because I planted a lot of shrubs on my small property, I pretty much have to rejuvenate continuously. And because last winter was too brutal for much pruning, my shrubs are in dire need of reduction/rejuvenation. So I started early, and here’s what one ninebark (Physocarpus opulifolius) looks like before (above) and after (below) pruning.
Note how crowded the plant at the top of the post looks. The largest stems are about an inch in diameter, and the plant is about 8 or 9 feet tall. It’s part of a hedge that was originally planted with coralberry, small hemlocks, two species of viburnum, and elderberry, in addition to the ninebark, with spring-blooming perennials below. Because of the ninebark’s large size and dense foliage, the other plants were getting shaded out, and because everything was so crowded, the ninebark itself developed an ugly case of powdery mildew last summer. So this winter I decided on radical rejuvenation: I removed much more than a third of the stems. On some plants I removed half or more.
Here’s the same plant after pruning:
The structure is the same, but the plant is considerably shorter and more open. I will be pruning all my shrubs, plus those of clients, in much the same way over this winter. I look forward to lots of young, vigorous growth in spring!