A sure sign of springtime is the scent of lilac – its recognizable, sweet-smelling aroma greets us for a few weeks each year. While we all love these scents and sights, finding our lilacs with less blooms and more scraggly branches each year is discouraging and many are left scratching their heads about the cause. Oftentimes, what lies at the heart of these sorts of issues is a matter of pruning.
Pruning: the task we all know is important, but usually the most confused about. When to prune and how to prune can be daunting, but with a little knowledge on how these spring-blooming beauties work, you’ll be able to prune effectively in no time.
It’s helpful to understand this about spring-blooming shrubs such as lilacs: after blooming has completed, the plant produces next year’s flower buds on the old stems. Therefore, you need to prune the lilacs immediately after flowering, which is about 2-3 weeks for appropriate pruning. The flower buds for next year will come in 3-5 weeks after flowering. Timing is everything when it comes to pruning lilacs. If you’re too late pruning (summer, fall, or even early spring before flowering begins) you will sheer all of the flower buds off and see no blooms next year.
It’s wise to deadhead your lilac once it’s finished blooming for the season. With a clean, good quality pair of pruners, cut the spent blooms off.
To help maintain the shape of your lilac, trim off any old branches that are unproductive or weak. Broken branches or dead wood should also be removed. Cut these branches close to the base to direct the plant’s energy to the stronger, more productive branches. You should also look to the top of your bush and trim the tops of branches to help keep your bush within reasonable height (6-8 ft. is average).
Take a look at the base of your lilac. Remove suckers that look weak, but think about keeping a few stronger looking ones to eventually replace your main branches down the road. Try to give your bush some space by pruning off any side growing branches or branches that are low to the ground as well. Cut away branches that are crossing one another or creating heavy crowding to help air flow and prevent disease at base of your bush.
Take a look at the branches that are tall and have produced blooms in the past. Remove a few branches that are beginning to look old or were weak performers on the bloom front this year. This will help make room for the better performing branches to fill out and grow, and give your selected suckers space to shoot up in the coming years.
This is the most drastic of all pruning, and is only required when the lilac has been badly neglected for a number of years, is very aged and consisting of mostly dead wood. These types of old lilac bushes require a rejuvenation pruning, which is pruning the entire plant to about 20cms off the ground. It will take the plant a few years to grow back, but it will reward your lack of bush and bloom for a few years with a fresh shape, rejuvenated branches and blooms, and an entirely new plant. After rejuvenation pruning, continue to give your lilac some shape and maintenance pruning each year to create a new and improved lilac sensation.
There are always many questions surrounding pruning, and we understand how confusing it can be! That’s why we’re here to help. Snap a few pics of your lilac bush (or any other plants you have pruning questions about), stop by, and one of our garden experts would be happy to help guide your pruning endeavours.