Is it too late in the season to trim back my lilac bush?

Question

This is the regular/common lilac bush that's next to the house and is now a couple feet over the driveway-grew like crazy this year! Do I have to wait until spring after it blooms? Or can I cut it back now?

Answer 1

Yes, it is too late. You can always prune dead or diseased wood at any time, but it's too late for any severe pruning of healthy wood now.

Pinch back your lilac to establish its shape, and remove old blossoms as promptly as you can. Remember that next year’s flower buds form in pairs where the leaves join the stems; severe pruning will mean fewer blossoms in the following year. As with other flowering shrubs, pruning is best done right after flowering if you wish to preserve as many of next year’s flowers as possible. If you need to completely renovate an older lilac or perform severe pruning, the best time to do this pruning is during the winter, while the plant is fully dormant. You can better see the structure of the shrub and disease and insects are not active in winter. A plant's response to pruning is to set out new growth. Now is not a good time to prune, especially if you live where we get cold winters. New growth generated now will not have enough time to harden before winter arrives and can be subjected to significant stem die-back. Also, disease and insects are still active. Pruned wood does NOT heal quickly at this time of the year and is an entry point for these active diseases and insects. Pruned wood heals the quickest in early spring, as the plant comes out of dormancy. Pruning right after a lilac has bloomed does allow the new growth to harden, but you still have created an entry point for disease and insects when they are active. Pruning right after blooming is a compromise that preserves the most blooms versus the risk to a plant's health. Wounds will heal during this period (though not as quickly as in early spring), so there is a slight risk of infections or insect infestations.

Additional Information: GrannyGrunt is absolutely right in that people offering advise here on YA should take the hippocratic oath: Do no harm! Pruning at this time of year can be harmful to your plants.

Additional Information: The original question was: Is it too late in the season to trim back my Lilac bush? I don't want to change the direction of this post to: When is the best time to prune a Lilac? But I feel that this may be pertinent to the original subject. When is the best time to prune a lilac is a simple matter of your priorities. If your priority is the health of your Lilac (& blooms are secondary), you will prune in the winter due to lower risk of disease infection, insect infestation and quickest healing rates following pruning. If your priority is aesthetics (flowering, which is why we plant Lilacs in the first place), then you will say that right after blooming is the best time because it's only a small risk and you have the least disruption of next season's blooms. This is why the experts say this latter period is the best time, because most people prioritize blooms first. Your choice can be different than the experts if you understand the underlying issues for their position & your priorities are different.

Answer 2

Depends on the type pruning. Generally the answer is Do Prune now! Any tip removal will take off next year's blooms. The buds have already formed. However, you can cut back those sections that overhand the driveway......I'd cut them all the way back to the ground or the main stem, wherever they originated. That way they won't be a problem next year. If you aren't up for that, just prune what overhangs and remind your self, next year prune in May-June!

Answer 3

Most of us like to think we are informed and many are. Incorrect information can be harmful. My advice........See what the experts say about it.
They all seem to agree on one key point.
there is a right way and a right time. Now is probably the wrong time. It might not influence next years blooming to cut out and remove old canes/stems/branches.
I have listed 3 links for you to read and decide.

Ron Smith, Horticulturist, NDSU Extension Service
http://www.ext.nodak.edu/extnews/hortiscope/shrub/lilac.htm
Questions on: Lilacs
When is the best time to trim our lilacs so we don't affect their flowering next year?
A:......... Right after they finish
................flowering this year!
The helpful gardner
http://www.helpfulgardener.com/lilacs/03/pruning.html
There are right and wrong ways to prune a lilac bush. There is also a right and wrong time. ...........Most importantly,
.............prune or trim back your bush
..................... immediately after they are
........................done blooming.
The gardners net
http://www.gardenersnet.com/lilac/lilac02.htm
There are right and wrong ways to prune a lilac bush. There is also a right and a wrong time. .....Most importantly,
..............prune or trim back your bush
...................immediately after
...................they are done blooming

Answer 4

No, it's not too late. If the bush is severely overgrown, prune it back by one third. Remove dead/dying branchs and cut back problem shoots at root level.
You won't get flowers next year but, you will have a much stronger shrub.