[CANUFNET] To Mulch or Not To Mulch

[Ward, Greg]

Taken from the University of Florida website (Gilman is an author)...

Robert J. Black, Edward F. Gilman, Gary W. Knox and Kathleen C. Ruppert2

A mulch is any material applied to the soil surface for protection or
improvement of the area covered. Mulches are frequently applied around
plants to modify the soil environment and enhance plant growth. The
mulch material may be organic such as bark, wood chips, leaves, pine
needles, grass clippings or similar material; or inorganic such as
gravel, pebbles, polyethylene film or woven ground cloth. 

BENEFITS OF MULCHING
Mulching has the following beneficial effects upon the soil and plants.


Mulches can prevent loss of water from the soil by evaporation. Moisture
moves by capillary action to the surface and evaporates if the soil is
not covered by a mulch.


Mulches suppress weeds when the mulch material itself is weed-free and
applied deeply enough to prevent weed germination or to smother existing
small weeds.


A more uniform soil temperature can be maintained by mulching. The mulch
acts as an insulator that keeps the soil cool under intense sunlight and
warm during cold weather.


Mulching will prevent crusting of the soil surface, thus improving
absorption and percolation of water into the soil and, at the same time,
reducing erosion.


Organic materials used as a mulch can improve soil structure and tilth.
As mulch decays, the material becomes topsoil. Decaying mulch may also
add nutrients to the soil.


Mulches also add to the beauty of the landscape by providing a cover of
uniform color and interesting texture to the surface.


Mulched plants will produce roots in the mulch that surrounds them.
These roots are produced in addition to the roots that a plant produces
in the soil. As a result, mulched plants have more roots than unmulched
plants.


HOW TO APPLY MULCH
Mulch entire plant beds with a layer of mulching material. When mulching
individual trees in lawns, create a circle of mulch about 2 feet in
diameter for each inch of trunk diameter. Increase the size of the
mulched area as the tree grows.

Pull mulch 1 to 2 inches away from the stems and trunks of plants. The
high moisture environment created by mulch increases the chances of stem
or trunk rot which can result in plant death. 

HOW DEEP TO APPLY MULCH
The amount of mulch to apply will depend on the texture and density of
the mulch. Many wood and bark mulches are composed of fine particles and
should not be more than 2 to 3 inches deep after settling. Excessive
amounts of these fine-textured mulches around shallow-rooted plants can
suffocate their roots causing chlorosis and poor growth. Course-textured
mulches such as pine needles and pine bark nuggets, which allow good air
movement through them, can be maintained as deep as 4 inches.

Mulches composed solely of shredded leaves, small leaves (oak leaves),
or grass clippings should never exceed a 2-inch depth. These materials
have flat surfaces and tend to mat together, restricting the water and
air supply to plant roots. 



GREG WARD | MANAGER, URBAN FORESTRY AND ENVIRONMENTAL PROGRAMS

Parks, Recreation and Culture
14645 - 66 Ave, Surrey, BC, Canada V3S 5M2
T 604.501 5170 | F 604.501 5177   www.surrey.ca

Please consider the environment before printing this email




-----Original Message-----
From: canufnet-bounces at list.web.net
[mailto:canufnet-bounces at list.web.net] On Behalf Of Anita Schill
Sent: March-31-11 6:42 AM
To: Canadian Urban Forest Network
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