The lilac is a shrub that gives off sublime fragrances in spring. However, its pruning is subject to controversy, with some gardeners insisting that it should be pruned only rarely and very lightly, while others do not hesitate to prune it back. Wouldn't the middle way be the best solution?
When to prune lilac?
The lilac can be pruned in two stages: in spring just after flowering to remove the faded flower clusters, then in autumn or winter for maintenance and cleaning. Note that this type of pruning will not be done on a young subject that is still too sparse. Wait at least 4 years after planting to consider a thinning out or a 'transparent' pruning.
Be careful, the lilac blooms on the previous year's shoots, if you prune too short and without restriction late in the fall or winter, you risk not enjoying its flowers the following spring!
How to prune lilac after flowering?
Use pruning shears whose blades have been disinfected beforehand (methylated spirits, flame...) and sharpened to ensure a clean and straight cut.
Just after flowering, cut back the deflowered stems by cutting just above the first big bud present under the flowering stem. Cut neatly, beveling away from the bud so that rainwater does not run directly onto it but on the other side. The bud will have time to develop and form a flowering stem for the following spring.
How do I do a cleaning pruning on the lilac?
As we have seen above, this pruning should only be considered on an old subject whose structure needs to be aerated.
Take a pruning shears whose blades will have been disinfected and well sharpened beforehand.
- In the fall or winter, cut back ¼ of the oldest stems at the base of the plant. This operation will encourage the birth of new stems while preserving enough branches to obtain a beautiful bloom.
- Take the opportunity to remove all the dead wood and branches that cross in the center of the shrub. The silhouette will thus be aerated and the shrub will be less prone to harboring pests. Better ventilated, the lilac will also be less likely to suffer from diseases.
- Cut off any suckers at their base.
How to prune lilacs back?
Rejuvenation pruning can be considered for very old trees that are not flowering well and have a gangly habit. This pruning is done at the end of winter in March or even a little earlier in the mildest regions, just before budburst.
- Take a pruning shears or a hand saw. Do not forget to sharpen and disinfect the blades beforehand.
- Remove all dead branches at their base and 1/3 of the oldest branches.
- Cut back the other branches to 30 cm from the ground by pruning just above a bulge in the bark (bud) facing outwards.
