Question
I am looking for a tree that will grow tall (for privacy) and narrow ( 6 to 8 feet wide -between existing pyramidal cedars). It will be planted between a fence and the walkway of my swimming pool. The future root is an major concern as I am worried about damaging the pool. The distance between the the walkway and fence is 4 feet. We live in Burlington, Ontario west of Toronto Ontario Canada and we are only 2 miles to Lake Ontario. Also looking for a tree that does not drop leaves, flowers, keys etc during the swimming season-May 15th to Oct-15th. Can you recommend a few different variety of tree we should look at?

Thanks

Answer
You are in a Canadian zone 6a (roughly a USDA zone 5).

Here are some clumnar/narrow plants that might fit the situation:  http://www.agnr.umd.edu/users/ipmnet/99-3nnws2.htm

I would avoid the maples, as they have invasive roots that could lift your concrete...

The Toronto Urban Foresty Service has a list of trees on their website that would grow in your area, but none are "narrow", so you may want to compare the first list, above, with their list (found at www.toronto.ca/trees)

Also, you might consider columnar shrubs like a Thuja or Yew.  ~Marc