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Lilaca Maintenance #926602

Asked March 23, 2026, 5:09 PM EDT

My lilacs got hit last year with two diseases and I'm wondering if cutting them all the way back is the best way to save them. If so, is it wise to cut back as close to 9-12" from the ground? When is the best time to cut them back? I appreciate your support. Thanks. Anne

Ramsey County Minnesota

Expert Response

Hi Anne, 

Thanks for reaching out! Here's a great article with tips about pruning lilacs: https://extension.umn.edu/trees-and-shrubs/lilacs

For general pruning, it's best to prune them immediately after blooming. This encourages good bud development for next spring. 

In your case, you may wish to follow "renewal pruning" (https://extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs#hedges-and-shrubs-1336763). This is when you remove 1/3 of the thickest stems every year, pruning them right down at the ground. It may take a few years to take care of all the stems. Once removed, you can go back to standard pruning. 

Finally, you could consider "rejuvenation pruning", which is where you cut the entire plant back to within 6-8 inches: https://lancaster.unl.edu/rejuvenating-older-lilacs/ Now is a good time to do this if you choose this method, but it will remove all flower buds and it may take up to three years to get them all back.

I hope this helps. 

An Ask Extension Expert Replied March 23, 2026, 6:55 PM EDT
Thanks for your quick reply. I'll make a decision soon.
Cordially,
Anne

On Monday, March 23, 2026 at 05:55:42 PM CDT, Ask Extension wrote:


The Question Asker Replied March 24, 2026, 1:20 AM EDT

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