My husband, Saint Paul, is a retired foot and ankle surgeon. Before he was a doctor, he was a physician assistant who worked on a heart transplant team. Even so, he is not allowed to prune our trees and shrubs without supervision from a more knowledgeable person … me.
I’m an expert on this topic. Just ask me. That’s why I declared I was taking charge of taming the overgrown lilac bushes in our back yard.
Common lilacs can grow 8 to 10 feet or taller. As they grow, the lovely flowers tend to cluster at the top. Before long, you have to crane your neck to see where the fragrance is coming from. Come spring, you might be tempted to cut those shrubs back a bit, but you’d be making a big mistake. That’s why you need an expert like me.
Lilacs flower on old wood. Through the summer, they actually make the buds that will turn into flowers next spring. If you prune your lilac before it flowers, you’ll have to wait another year until it blooms. I knew that, so I waited until after it bloomed to start cutting our lilac back.
As lilacs mature, they tend to get “leggy.” That means many of the branches are leafless at the bottom. All the action’s taking place at the top. To rectify this, horticulturists recommend a technique known as “renewal pruning.” The idea is to select one-third of the oldest, tallest, woodiest branches, cutting them off at the base of the plant. This will spur the plant to send up new shoots. The next year, you remove another third, and so on, until your shrub is filled out with shorter, robustly growing branches.
So, that first year, I pointed out the branches I wanted removed. Paul was a bit dubious when he saw the number of 3-inch-diameter branches I had chosen.
“Don’t worry,” I told him. “I went to a lecture about this. I know what I’m doing.”
The lilac responded beautifully, sending up new shoots before the summer was over.
The following year, those new branches looked vigorous and leafy and just the right height, but they did not produce any flowers.
“Maybe they need one more year,” I said somewhat less confidently. Nonetheless, I plunged ahead with removing the next third of the old branches.
The following spring, the only flowers on the lilac were those on the remaining third of old branches. Taking a leap of faith, I cut them back because by now they just looked silly and awkward rising so far above the new foliage.
The next year, the sainted Paul had not mentioned that there were still no flowers on this shrub, which was, finally, the right height. I was preparing to admit my fallibility when I was saved by a guest on Larry Meiller’s “Garden Talk” radio program. The guest, an actual expert, mentioned that lilacs often take three to five years to start blooming again after renewal pruning.
In year four, pretty much on schedule, our lilac started blooming, allowing me to continue to believe I know what I’m doing. And that’s blitz.
Patrice Peltier lives in Spring Green and writes regularly for Wisconsin Gardening, Chicagoland Gardening and The Landscape Contractor magazines. Her work has appeared in Better Homes and Gardens and Midwest Living magazines.