A New Tree
by Rena Viehbeck, Urban Forest Program Specialist with the City of Thunder Bay
Published in the Thunder Bay Chronicle Journal, Saturday, May 10, 2014
If the warmer weather has got you thinking about tree planting this spring then species selection will be
one of your main decisions. There are a few important considerations to keep in mind when you head
out to your local nursery.
Plant Hardiness:
To begin, you will need to consider our local climate when selecting the appropriate tree. You will want
to ensure that the tree species you select is cold tolerant to our Canadian Plant Hardiness Zone 3A (Zone
2b for Kakabeka Falls and 2a for Lappe areas). If the tree does not have a label indicating its plant
hardiness then be sure to ask someone at the retailers that knows. Unfortunately, there are many tree
suppliers who will sell tree species that are not appropriate for our plant hardiness zone and although
the trees may look nice in the spring and summer they will not survive our winters.
Urban vs. natural forest:
It is also important to note that the urban environment is not a natural setting for tree growth, and
conditions can be very difficult, especially if the trees are located in proximity to a road or driveway. For
this reason cultivated species that are tolerant to many of the urban growing conditions are great
alternatives.
Native species vs. cultivars:
If you are looking to plant a native species, the Thunder Bay forest region has a limited number of
species appropriate for urban tree planting, in comparison to more southerly ecosystems. Native conifer
species found in the region’s forest are great options if you are looking to plant in an open space or to
create a living buffer.
As for deciduous trees, there are two that previously did well in our region but are now unsuitable for
planting. Ash (Fraxinus) and birch (Betula) are both threatened by present or imminent pests, namely:
the bronze birch borer (birch trees) and the emerald ash borer (ash trees). All ash trees will either die
and need removal, or will require treatment with a costly pesticide when emerald ash borer arrives.
Birch trees also suffer in drought conditions and will most likely require additional watering throughout
their entire life.
Native poplars sprout many sucker shoots, drop sticky buds and produce copious amounts of seed.
They are also a fast growing tree that do not have long lifespans and require investment of pruning in
order to remove hazards. These are important considerations if planting close to a building.
Native sugar maples rarely survive in urban environments although sugar maple cultivars are a great
alternative.
Elm trees were once planted on mass and did well in Thunder Bay until the arrival of the Dutch Elm
Disease (DED) which eliminated most local elm. DED is still a threat to local elm trees however there are
some elm cultivars that are resistant.
Bur oak and mountain ash are some native species that do well locally and are planted frequently by the
City.
If you would like a list of trees that are being planted by the City and doing well in Thunder Bay please
visit thunderbay.ca/urbanforestry and click the ‘Request a Tree link’.
Location:
Two additional thoughts, both in regards to tree location. Ensure that the right tree is planted in the
right place. This means that before you plant your young tree you need to consider the space
requirements of the tree above and below ground when it has reached maturity. Look above the tree
and all around to ensure that the tree will not interfere with power lines or visually block an important
feature. Short stature trees, such as crab apples and many others, are great alternatives when space is
limited. And finally, be sure to call ‘ON1Call’ before you dig and find out what is underground in order to
prevent potentially very serious damages.