huge, old lilac bushes - Ask Extension
I bought a property two years ago and it has three out of control very old lilac bushes. I cut away some old, dead branches recently and am now at a l...
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huge, old lilac bushes #878240
Asked July 22, 2024, 11:52 AM EDT
I bought a property two years ago and it has three out of control very old lilac bushes. I cut away some old, dead branches recently and am now at a loss as to what I should do. I have watched a few Youtube videos and I am pretty sure I am supposed to cut these bushes down to a foot to a foot and a half so that they can rejuvenate. It is a drastic measure for me as I enjoy gardening, but am certainly not a master gardener. Can I use a chainsaw? Is it okay to do this now or should I wait until after they flower next sping as the Youtube video suggests? Is there a master gardener who does house calls? One bush has leaves that are currently wilting and turning brown. What does this mean?
Goodhue County Minnesota
Expert Response
I don't know if this is a required item. I thought I was being specific and detailed. How and when should I prune my lilac bushes? They are old and have not been maintained. They are maybe 12-13 feet tall. Lots of big branches- length and diameter.Leaves are also dying on my bushes-- turning brown. My neighbor says hers are turning brown as well. I don't remember this from last year, so maybe it has to do with all the rain.
https://extension.umn.edu/trees-and-shrubs/lilacs#pruning-1923160
What you should do next depends on what you want the bushes to look like and if you want flowers every year. If you want to start over with short rounded shrubs that may take 3-8 years to resume flowering do renewal pruning. Instructions are in the guide. If you want taller bushes that flower every year take out 1/3 rd of the bush and select the oldest stems first. Do this every year until all the old stems have been removed.
Regarding the lilacs turning brown, unfortunately lilac blight is rampant this year. It may be what is happening to your bushes. I can’t tell from a photo. Please see the information at the links.
https://yardandgarden.extension.iastate.edu/encyclopedia/lilac-bacterial-blight
http://plantclinic.cornell.edu/factsheets/lilacbacterialblight.pdf
What you should do next depends on what you want the bushes to look like and if you want flowers every year. If you want to start over with short rounded shrubs that may take 3-8 years to resume flowering do renewal pruning. Instructions are in the guide. If you want taller bushes that flower every year take out 1/3 rd of the bush and select the oldest stems first. Do this every year until all the old stems have been removed.
Regarding the lilacs turning brown, unfortunately lilac blight is rampant this year. It may be what is happening to your bushes. I can’t tell from a photo. Please see the information at the links.
https://yardandgarden.extension.iastate.edu/encyclopedia/lilac-bacterial-blight
http://plantclinic.cornell.edu/factsheets/lilacbacterialblight.pdf
When should I prune the lilacs? Youtube video said right after they finish blooming and start turning brown. Is it okay to cut a 1/3 of the branches away right now?
Robyn Evans
EL Teacher
Lyndale Elementary Minneapolis Public Schools
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From: ask=<personal data hidden> <ask=<personal data hidden>> on behalf of Ask Extension <<personal data hidden>>
Sent: Monday, July 22, 2024 4:30 PM
To: Robyn Evans <<personal data hidden>>
Subject: [EXTERNAL] Re: huge, old lilac bushes (#0148158)
Sent: Monday, July 22, 2024 4:30 PM
To: Robyn Evans <<personal data hidden>>
Subject: [EXTERNAL] Re: huge, old lilac bushes (#0148158)
You should wait until late winter or early spring when daytime temps at above freezing. Fungal and bacterial diseases are very, very common and widespread this year so this is not the time to make pruning cuts/wounds. During the winter and early spring pathogens are not so prevalent.
