- Norway maple (Acer platanoides) - The Norway maple is no longer considered a suitable choice for a shade tree. It has escaped from cultivation and is vigorous enough to squeeze out native sugar maples. The Norway maple has such a dense canopy that virtually nothing will grow under it. We had Norway maples on a previous property we owned. The general consensus is this is a junk tree more akin to a weed than a tree. One Norway maple will quickly see others sprout up. You have to constantly remove the seedlings as they grow very quickly as much as 3 feet per year in height! Choose native sugar maples instead.
- American Basswood (Tilia americana) - The American basswood is an Eastern native that is scrubby when young but matures to a dense globe. It is not a well behaved tree and is prone to insects and disease. Choose littleleaf linden (Tilia cordata) that has a neater appearance and is disease and insect resistant instead.
- Scots pine (Pine sylvestris) - The Scots pine with its reddish brown bark has often been used in reforestation projects. It has become naturalized as a result. However, native pine species that encourage natural woodland ecosystems should be used instead.
- Weeping willow (Salix babylonica) - The weeping willow is a romantic tree with its gracefully drooping branches. It is often planted along river banks to help prevent erosion. We had several weeping willows along the river bank in my childhood home. They provided many a summer afternoon of swinging on the branches over the water. I was elated that our new home had a beautiful weeping willow. We moved in the end of June and by mid October we had our first plumbing problem due to the willow. The following March we had a more serious problem also caused by the willow. The roots are extensive and they make a beeline for tile drains and sewers. They are also prone to disease. The trunk of our tree is about 4 feet so it is an old tree and I do not want it removed. However, I may not have an option as over the winter a severe storm broke a large limb about 1 foot diameter that hasn't fallen completely yet and there are signs of other large limb damage. My husband arranged for the tree to be professionally assessed to see if it can be saved or should be removed. If you are considering planting a weeping willow do keep in mind the expensive problems the roots can create. Plant it only in wide-open spaces well away from sewers and tile drains but don't be surprised if you have a problem later due to the roots.
- Australian pine (Pinus nigra) - The Australian pine has been a favourite in urban landscaping because it is a tough tree that is able to withstand the damaging effects of smog, salt spray and poor soil. In rural settings choose native pines instead.