Proper tree pruning is essential for achieving the growth, development and structural
integrity for a strong, healthy and aesthetically pleasing tree.
Trees do not have the ability to regenerate cells, but can only generate new cells and shed
or store old or dead tissue so any wounds or damage that is done to a tree is there for life.
As a result, trees must compartmentalize, or grow over, seal off and form barriers around any
wounds or damage. Small pruning cuts to young or juvenile trees does significantly less damage
than larger cuts to more mature trees as they tend to compartmentalize faster. Large cuts or
wounds to older trees often result in permanent damage and decay with a greater exposure to
potential insect and disease problems.
The establishment of a trees lowest permanent branches as well as the primary scaffold
branches are best undertaken when the trees are young. These scaffold branches will form the
framework of the mature tree. Trees that have developed a strong branch structure will require
less corrective pruning as they continue to grow and mature.
The Urban Forestry Section with the City of Mississauga regularly undertakes routine street
tree elevation pruning programs in various communities throughout the City. These pruning
operations are necessary to ensure that tree limbs are not damaged or ripped off by garbage or
recycling trucks, snow plows or other vehicles using the roadways and that proper clearance is
maintained over the pedestrian sidewalks. Provincial standards require a 4 metre clearance over
roadways and 2.5 metres above the sidewalk. The trees scheduled for elevation programs have
generally been established from between 10 to 20 years.
The removal of the low branches from these young trees often results in temporary
disfigurement of the crown. As the trees continue to grow and mature in height and size, they
will develop into their natural balanced form while providing the required clearances over the
City right-of-way similar to the older trees in more established locations throughout the City.
The Urban Forestry Section employs qualified personnel and Certified Arborists utilizing tree
pruning standards that are consistent with the International Society of Arboriculture (ISA)
which addresses the tree's response to growth and wound closure as well as the proper long term
sustainability and structural integrity of the tree.
For further information, please contact the Urban Forestry Section at 3-1-1 or 905-615-4311
if outside the City limits or visit the International Society of Aboriculture Web