[CANUFNET] To Mulch or Not To Mulch

[terri smith]

We are planting in individual holes which are surrounded by turf.  I spoke with Ed Gilman and Hannah Mathers after their talks and they both agreed there is little benefit to mulching beyond the tree wells in this case.  Each year, we remove grass from around the tree wells so mower/trimmer damage is not an issue because they don't need to mow anywhere near the trunk.  Applying 2-2.5 inches of mulch outside the tree well is not sufficient for weed control.  We have been using 3 inches of mulch for years now and each year we are required to weed the mulched area because weed seeds blow into the mulch and germinate, we also find ourselves removing grass that continues to grow under the mulch.
 
I am curious to know what type of organic mulch you have been using.  We only have access to wood chips and it has been proven time and again that wood chips take nitrogen from the soil.  I understand leaf litter benefiting native tree stands however wood chips are an entirely different matter. 
 
Thank you for directing me to the Illinois conference.  This is a paradigm shift and as always, it is stimulating a lot of debate, which is good.  We will be changing our practices this year and pulling mulch off the tree wells, not removing it entirely.  Whether we discontinue mulching altogether is another matter and it will depend on further findings.
 
Terri Smith
Urban Forestry
City of Saskatoon    
 
> From: aschill at oldscollege.ca
> To: canufnet at list.web.net
> Date: Thu, 31 Mar 2011 07:41:49 -0600
> Subject: Re: [CANUFNET] To Mulch or Not To Mulch
> 
> Landscape Below Ground III was held in Illinois in 2008 and there were several presentations and demonstrations about mulches. I would highly recommend purchasing the proceedings. Basically, organic mulches improve shoot growth, root growth, as well as soil physical chemical and biological properties. I was amazed to see how quickly an urban soil (compacted, layers of different fill soils, etc..) was able to develop some structure under a mulched situation.
> 
> Ed Gilman is one of the editors of the proceedings. I too have recently heard Ed talk about mulches and I think there may be some misunderstanding. What he said was it was not beneficial to place mulch directly on the rootball surface at planting but, by all means, mulch to the rootball. I don't think that deviates too much from our practices unless we are still planting individual trees in individual holes surrounded by turf. It's worth testing. Anytime you plant large mulched beds with several trees, remove the mulch from the surface of the root ball on some trees and not to the rest. Let the rest of us know your findings.
> Anita Schill, PAg.
> RCA #421
> ________________________________________
> From: canufnet-bounces at list.web.net [canufnet-bounces at list.web.net] On Behalf Of pwynnyczuk at richmondhill.ca [pwynnyczuk at richmondhill.ca]
> Sent: Wednesday, March 30, 2011 1:30 PM
> To: Canadian Urban Forest Network
> Subject: Re: [CANUFNET] To Mulch or Not To Mulch
> 
> Hi Terri,
> What happens to exposed soil around the base of the tree or anywhere, .....erosion, soil compaction...heat build up...are these factors that affect recently planted trees survival?
> No mulch, could attract weed seeds, which then germinate and attract string trimmers....
> 
> A couple of inches helps address the above and allows for the creeping of grass to the base of the trees over a few years.
> This is based on a few years of Blvd tree planting.
> 
> Look forward to the continuation of this question.
> 
> Regards,
> Peter Wynnyczuk
> 
> Urban Forestry Supervisor
> Town of Richmond Hill
> Community Services Department
> Telephone: 905 780-2930
> Fax: 905 780-2928
> Internet: pwynnyczuk at richmondhill.ca
> 
> 
> 
> 
> From: terri smith <janedatsun at hotmail.com>
> To: Canufnet Canufnet <canufnet at list.web.net>
> Date: 03/30/2011 02:57 PM
> Subject: [CANUFNET] To Mulch or Not To Mulch
> Sent by: canufnet-bounces at list.web.net
> ________________________________
> 
> 
> 
> I would like to know if there are any municipalities that have stopped applying mulch on newly planted boulevard trees. Current research indicates that mulch should not be placed over the root ball because it causes roots to grow up into the mulch area, it also causes roots to remain within the root ball area instead of growing out laterally, and it actually prevents the water from penetrating deep into the soil. Dr. Ed Gilman and Dr. Hannah Mathers both agree that no more than 2 – 2.5 inches of mulch should be applied outside of the root ball area (if mulch is still going to be applied) and both are in agreement that mulch provides no benefit to the tree. At 2 inches of mulch there is little to no weed suppression.
> 
> These new findings contradict our current mulching practices and have created much debate within our department. I would like to hear from other municipalities that have either discontinued mulching or have never mulched their blvd trees. Is there a need to increase the amount or frequency of watering?
> 
> Terri Smith
> Urban Forestry
> City of Saskatoon
> 
 		 	   		  
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