Question from James:
We have a lovely 71 year old olive tree, in Long Beach, CA planted next to a retaining wall (trunk is 4-5 feet from the wall) that is now causing the wall to lean.  The wall needs to be replaced, and cannot be placed farther way from the tree because it is located on the street with a 12 foot setback from the curb.  We are in the planning stages of wall replacement and are at the point of either removing the tree (a heartbreak!) or keeping the tree by containing the tree’s roots so that the wall will not be deformed by the tree’s root structure in the future.  I have two questions for you.   Can a root barrier be used effectively? If so, can you recommend a dependable, experienced landscaper in Southern California, capable of such a task?

Answer from Pat:
First I would like to refer you to the questions and answers on this subject elsewhere on this website. Though your question is slightly different, the information on root barriers, curbs, and olive trees is similar. There is much information given in my answers there which will help you with your problem.

Now for a specific answer to your unique situation: Since the sidewalk is four to five feet from the wall I think a root barrier would work extremely well. Arborists often say roots should not be pruned closer than seven feet from the trunk so the tree does not tip over, but in the case of an olive tree the danger of it tipping over is virtually nil. (Please refer to the detailed instructions I have already given in response to other queries.)  I certainly would not remove the tree. Olive trees are extremely resilient. I was on an olive ranch in Italy only three days ago and saw several 500 year old specimens that had withstood all manner of trauma, including roots cut by a road, and they still lived and continued to bear olives.

As far as a contractor to do the work, I do not know of one. One possibility would be to ask your Farm Advisor for a recommendation. Another idea is to ask the advice of a top flight local nursery near you, such as Rogers Gardens in Corona del Mar. At any rate I would consult with a local professional Arborist before root pruning. As I have stated before however, olive trees are more resilient than most other trees.

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