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Pruning Laurel Hedge - confused

Last post 20-08-2012 10:11 AM by Tom Bainsfield. 10 replies.

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  • 21/09/2010 09:49 PM
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     When can I prune my laurel hedge?

     When I say prune, I mean take off several feet in height to reduce it to about 5ft.  And when I say hedge, I mean several hedges. And I've already started!

     So, I thought you were supposed to prune in winter when the plants were dormant, but I decided to have a little go this week to check if I could do it myself.  Turns out to be easy and really therapeutic. Then hubby says I shouldn't do any more until October at the earliest.  So I look online to check and most sources say that I should leave it until April, except for the ones that say do it in August and the others that say any time when there's no risk of frost because frost means canker will get in and kill the hedge, oh and then there are the  ones that say it is impossible to kill a laurel and to do it whenever.

     There's so much to do that I had planned to do it gradually over the winter but now I really don't know.  Someone tell me what to do, please!

  • 21/09/2010 10:05 PM
    • Phot's-Moll
    • The sunny South coast.
    • 06 Jan 2007
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     If you cut now, there's a danger the plants will produce soft new growth this Autumn that might then get damaged by frost.
  • 22/09/2010 08:07 PM
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     Hi dollydolittle,

    Am I right in assuming that these are mature, well established hedges that need reducing in height?

    If that's so, then you can pretty much trim them when you please.

    Phot's-Moll is right about tender new growth being damaged by frost - with the unpredictability of our weather, it's hard to say if a) the plants will put on any more growth now and b) if they do, will the new growth have time to harden.

    The big advantage of waiting until winter is that the plants will send most of the sugar they slaved away to make during the summer down to storage in their roots.

    Because you are taking off a large amount, chances are that your hedge will look a bit bald for a while. By pruning in winter & letting them save their sap, you will help them bounce back swiftly next spring.

    In the future, you can use this principle in reverse: you have a mature hedge that you wish to keep at a fixed size. By trimming in late summer, you will deprive it of some of the sugars it made, helping to keep its growth in check.

    I reckon leave it a month or two and then get stuck in.

     Have fun,

  • 22/09/2010 10:13 PM
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     Thank you! 

    You are correct, we have large hedges, very deep and in places probably ten feet high. There is evidence that they have been pruned back hard (down to four foot or so) in the past. So they are definitely mature. I think it all got a bit too much for the previous owners to cope with and they just let them go on up.

    What you and Phots Moll say makes sense.  I am keen to prune this winter, not least because there is so much to do in spring that I just wanted to get it out of the way, and it's nice to have something to do in the garden in the winter months.

     Another question - apparently we can't make a bonfire out of the branches as they release cyanide Is that right?  And does that also mean that I shouldn't compost any of the leaves?  We are going to have an awful lot of this stuff  to get rid of..

  • 23/09/2010 12:59 AM
    • AlexS
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    Hi Dollydolittle,

    A Couple of points: I'm assuming we're talking about cherry laurel, prunus laurocerasus.  If so, it has a surge of growth in late April and May, so whenever you prune it, it will look pretty bare until then.  Because of this, I always plan to do any hard pruning of laurels in March or thereabouts, as the new growth follows very quickly.  If you don't mind it looking bare for a few months, I don't think it matters much when you prune it, as it's a tough plant with great powers of recovery.

    I have pruned mature laurel hedges right down to the ground, and they've promptly regrown.  And I've made a bonfire of all the outturn - pretty smoky when it's fresh, but it burns very well nonetheless.  I've never heard of anyone suffering from the ill-effects of the smoke, although no doubt inhaling any smoke is best avoided.

    The leaves are very slow to break down, and I'm told they inhibit the germination of other seeds. However, the wood and leaves shred very easily.  I've mixed shredded laurel leaves and branches with other compostable material and produced good compost. Another thing I've done is to simply put all the leaves and branches back, as a mulch, under the hedge. That works fine.

    The other thought that occurs is that, if your local council has a garden refuse collection scheme, and you're planning to cut the hedges back over the winter, you could feed the outturn bit by bit to the council.  

  • 23/09/2010 01:03 AM
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     Hmm, I'm wary of giving advice about the cyanide aspect. This is all strictly non-legally binding, amateur advice and if anyone dies they are not to come crying to me about it.

    Important to bear in mind that cyanide is not an element (like arsenic), it's a group of compounds of nitrogen and carbon (two otherwise very popular & useful atoms - it's all in the bonding!)

     So a) not all cyanides are the same and b) compounds tend to break down / change when they get burnt. 

    Also , I wouldn't advise anyone to inhale great lungfuls of smoke from any bonfire. Once the smoke has spread a few metres it will be floating up into the sky, increasingly diluted by the air. So I really doubt that that's an issue.

     As for compost, what could be poison for people is food for fungi & several myco-members of your compost crew will say thanks for the cyanide, what's for dessert? Compost away.

     The only note of caution is that cherry laurel gives me an impressive rash when i trim it, so long gloves might be a good idea.

    I always wear eye protection when trimming, but that's more to prevent me from stabbing myself in the eye with the trimmer. Smile

    Have fun! 

  • 23/09/2010 01:31 AM
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     Yes, good point AlexS -  our composting space is limited, so we do use our shredder quite often & laruel leaves are indeed slower to decay than leaves from most other trees.

    I would advise against using the fresh leaves as mulch if you are in a humid area where laurel can be prone to shot hole - a non-serious fungus that does cosmetic damage.

    For easy leaf mulch, it's safer to collect all the leaves, stick em in bin liners, poke some holes in said liners and then leave them somewhere out of the way for a year or two. You'll end up with beautiful leaf mold mulch.

  • 23/09/2010 03:49 PM
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     I promise not to haunt you! 

    I don't think we'll be burning though as hubby is convinced it is A Bad Thing, but I'm pleased I can do the leaf mulch. We're going to have so much woody stuff to get rid of that I think we'll just pile it up and get someone to take it away all in one go. 

     Thanks for the science info as well.  I'm one of those people who has to understand why before I do something.  Oh and get the rash as well, which is another reason to do it in winter because I can be thoroughly wrapped up without overheating.

  • 23/09/2010 04:10 PM
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    I had been led to believe that the thing with laurel is to avoid inhaling the sweet and pleasant smelling "fumes" given off by newly shredded Laurel (wood and leaves) . Apparently these cyanide fumes can do your lungs a great mischief. I would love to have a profession view on this though. I do know far too many old wives!

  • 23/09/2010 09:11 PM
    • jon jon
    • stratford on avon
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    hi there november 5 is a good time for bonfires Big Smile

  • 20/08/2012 10:11 AM
    • Tom Bainsfield
    • Brixham and Central France
    • 20 Aug 2012
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    Reply | Contact Laurel All parts of the laurel are poisonous, though there are few reported cases of serious illness. The berries are the most likely to attract children. A case in Bolton in 2000 involved a child being taken to hospital with drowsiness which was diagnosed as having been caused by eating or chewing a laurel berry. However, there is no doubt it is extremely dangerous if very much is eaten as it contains cyanide. The leaves and stems contain small quantities of cyanide. Bundles of crushed leaves were used in ancient times to poison wells. Emperor Nero used laurel water to poison the wells of his enemies in Rome. Laurel water (distilled from the fresh leaves of the laurel) was used in Victorian times as a medicine. However, there is a case of a death reported when it was mistaken for an alcoholic spirit and drunk by a chemist's cleaner. Effectively, it contains hydrogen cyanide. Crushed leaves were used by butterfly collectors (in a closed jar) to kill the butterflies. Commentators advise against burning the leaves and clippings as they also give off cyanide. It would be wise not to do so or to keep well away from the smoke. There are cases, however, where people have become ill through inhaling the vapours from the shredded leaves, including professional gardeners who have transported the shredded leaves and branches in an enclosed van. It would be advisable not to shred laurel leaves.