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Tuning in to trees


Published: 06/27/2012


 One doesn't so much plant trees in the garden as invite them in as honoured guests. If that sounds fanciful, just remember that many of them will still be around long after we have moved on, and that during our time together they become partners in the gardening process by influencing what can or can't be planted in their vicinity.

As honoured guests, trees deserve the most thoughtful treatment. We may be choosey, whimsical even, over which specimen to invite to share our landscape, but once in, no decision concerning a tree's well-being should be taken lightly.

In this column we will discuss trees in general while citing the maple family for examples. A future column will cover the selection and care of trees in greater detail.

Traditional landscape painters learn early that the vista before them may be divided into three parts: foreground, middle ground and distance. When considering which specimen of tree to plant, you may regard your garden, from the house, in much the same way as the painter and select small trees for the foreground, medium trees for the middle ground, and large trees for the distance. Strict uniformity in any form of horticulture can be boring, however, so by all means break the rule from time to time.

Similarly, it is logical to try to maintain a sense of proportion by matching your choice of trees to the lot and building size, but a whole neighbourhood so laid out would look utterly boring.

Be especially careful about planting large trees up close to the house. That winsome sapling you spot at the nursery may grow to become a 15-metre giant with a huge spread. While it might provide your house with welcome shade in summertime, its root system can play havoc with the foundation and sewer line in its endless quest for moisture. And the closer to the house, the more frantically the roots forage, since the house tends to screen the tree from the rain and to deprive it of the runoff.

When you consider that a tree's root system is about the same size as its above-ground growth, you realize the problems that can occur under the ground when a tree gets desperate for moisture.

People living with overhead utility lines must also be careful as to what they plant and where, for few things look as sad as a tree whose main stem, or leader, has had to be lopped off to accommodate a power line. Leaves plugging the eavestroughs are another drawback to planting large trees too close to the house.

Not unnaturally, the maple (Acer) in such various forms as Silver, Red, Manitoba and Norway is a favourite of Canadian gardeners but it can be a selfish, greedy guest. Generally, its root system is shallow, which means it will compete vigorously for nutrients in the topsoil all around. Since it creates dense shade too, other plants will not readily grow in its vicinity. In fact, many gardeners, me included, have given up on the task of gardening directly beneath a maple, resorting instead to building a deck and growing shade-lovers on it in pots.

Some gardeners say you can raise the bed below a maple and plant in it but that's only a temporary fix: Those roots soon wise up to the situation and work their way to the surface. Besides, it is bad news to mound soil around the trunk of any tree, except perhaps as winter protection for new plantings. Mounded soil can suffocate the roots and encourage bugs to attack the bark and underlying cambium. Once the tree has been girdled, it dies, unless you get in fast and fix it with a transplant.

I don't wish to pick on maples but another reason you may wish to avoid them is that there are already so many of them in our area, and if they get struck by blight or ravaged by a pest such as the Asian Longhorned Beetle, the gaps in our landscape will be frightful. This is reason enough to diversify and select less common specimens for our yards, though there are other valid reasons, including aesthetics and the conservation of certain minerals and trace elements in the soil, since different plants (trees included) have different needs.

Of course, any admonition with regard to the maple does not apply to ornamental versions such as the Japanese Maple, which makes an excellent foundation or specimen tree.

In Toronto , the Urban Forestry Services group will plant a tree for you on city street allowances fronting residential properties for free. Just call 416-338-TREE. You may select from about 30 specimens, with about a half being native to North America. This department will also perform repairs and maintenance to trees on city street allowances, including stump removal.

For tree planting in the backyard, you may contact LEAF (Local Enhancement and Appreciation of Forests), which is a local non-profit group. It offers Toronto residents a subsidized tree planting service, including on-site advice on appropriate species and planting location, a 1.2-m to 1.8-m tall native tree, and the physical planting. Native shrubs are also available. You cam contact LEAF at 416-413-9244.

Finally, under the Toronto Municipal Code, healthy trees are protected once they reach a certain size (a trunk of 30 cm diameter at 1.4 m above the ground), even on private property, and you will require a permit before felling them or taking any other drastic action such as moving them. Diseased or dead trees may be removed without a permit, as long as their condition has been identified as such by a registered expert.

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