How Do You Prune Lilacs?
Removing Deadheads for Maximum Bloom and Rejuvenated Flowering
How and when lilacs are pruned has a large impact on how much they'll bloom. This article will explain it all.
Lilacs are fragrant, old-fashioned harbingers of summer. The nostalgia attached to lilacs is matched only by the amount of confusion they incite about how to keep them looking fabulous. There are five simple guidelines to follow to keep lilacs looking their best.
Prune After Bloom
If flowers are the goal (and, with a lilac, is there really any other purpose?) the most important thing to keep in mind is that they bloom on the previous season's growth. So, if you were to go out and prune them in late autumn or early spring, in an attempt to “clean up” the garden, you'd be cutting off all of the potential blooms. Let the flowers bloom, enjoy their heavenly scent, and then prune away----Prune After Bloom!
Deadhead
After lilacs bloom, and it's safe to prune them, the most important thing to do is to deadhead them. What this means is that it is necessary to cut off the spent flowers. If you leave the spent blooms on the plant, the lilac will put most of its energy into seed production (seeds, of course, are the ultimate result of flowering) instead of making flower buds for next year. The easiest way to do this is to simply snip the blooms off after they fade. If this is the only thing you ever do to your lilac, you'll be rewarded with blooms aplenty.
Rejuvenate
We've all seen those sad lilacs that look like nothing more than sticks with a bunch of blooms way up at the top, where we can barely see them, let alone enjoy them. This is the inevitable fate of lilacs, thanks to their habit of blooming on the previous season's growth. When lilacs start looking leggy and overgrown, it's time to rejuvenate them. This is done, very simply, over the course of three years.
- Year One: Cut out the oldest, thickest branches, about one-third of the total branches (after bloom, of course!) Cut as close to the ground as possible.
- Year Two: Cut out another one-third of the older branches.
- Year Three: Cut out the remaining older branches.
What this does is stimulate the growth of young branches, which will bloom more vigorously than the old branches did, and at a height where you will be able to enjoy them. By the end of Year Three, your lilac will be vastly improved.
Remove Dead Wood
This is basic pruning that can really be done at any time. Most often, it's done in the spring, when it's easiest to tell which branches didn't make it through the winter. If the branch isn't dead all the way back, simply cut off the dead part just above a live node. If it's dead all the way back, just cut it down to the ground.
Shaping
Lilacs do best when left to their natural habit. Trying to prune them into cubes or spheres is an exercise in folly. Sometimes, though, lilacs will develop branches that cross and rub other branches, or branches that grow taller than the rest and make the shrub just look, well, weird. These should be pruned out as well. In the case of crossing branches, take them off back to the ground. In the case of a branch that's grown taller than the rest, simply prune it back to a more reasonable length, cutting just above a node.
