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Hi, I have a row of a ... #170037

Asked March 13, 2014, 4:20 PM EDT

Hi, I have a row of a dozen white fir that is about 40 feet tall. They were probably planted in 1960. They provided plenty of privacy when we first moved in (30 years ago) but have thinned out at the lower levels and their tops now block the winter sun from our south facing windows. Could I top them at 30 feet? When would be bet time to do it? Or do I need to replace them? If they only have a 50-year life, what happens when they reach the end of their life span? Are there urban foresters that would take them down and make lumber out of them? I've thought about replacing them, what would you suggest? The neighbor's elm cuts down some of the direct light on the lower third of the current firs. Thanks

Hennepin County Minnesota

Expert Response

Topping the trees will permanently disfigure them and may shorten their lives.  If that's of no concern, it can be done, but replacing the trees is a better way to achieve your goal in the long run.

Conifers that age and die naturally decline over time.  Branches damaged or broken by insects, disease and storms are typical signs of aging. The lower level branch thinning you mention is likely to move upward.

It's unlikely that anyone will be interested in harvesting the trees for wood products.  As this subject relates to black walnut trees, a University of Ohio bulletin puts it this way:

"The cost and difficulty of harvesting urban trees also discourages the purchase of urban walnuts. Unless the trees are of truly exceptional value, it is rarely economical for a buyer to invest crew and equipment time in traveling to harvest one or two trees. In addition, many urban trees are close to houses, power lines, or other facilities, making them more difficult, time consuming, and expensive to harvest."

These factors are also likely to preclude harvest of the fir trees. Go here to read the entire bulletin: http://ohioline.osu.edu/for-fact/0044.html

Arborvitae tolerate partial shade and may be a suitable replacement for the firs.


An Ask Extension Expert Replied March 13, 2014, 11:19 PM EDT

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