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Tuesday - February 19, 2008

From: Murrieta, CA
Region: California
Topic: Shade Tolerant
Title: Selection of shade tree and distance from house
Answered by: Barbara Medford

QUESTION:

I live in California in zone 8b. I have seen the lists of trees for my area. I am still not clear on what tree to select. I would like to plant a nice tall shady tree very close to my house, but I want to make sure its roots do not cause a problem later. Any suggestions?

ANSWER:

We're assuming that when you refer to "a problem", you mean both for the tree and for the hardscape, like foundations, sidewalks, and driveways. Since your city of Murrieta, California is in southwestern Riverside County and thus near San Diego, we thought you would find this article prepared by The National Wildlife Federation/San Diego County of interest. Most of the current information on preservation of trees has to do with protection of the tree during construction. However, if we correctly understand you, you want to plant a shade tree that will grow pretty tall close to your house.

The operative term here is probably "close". When a tree is being planted, there needs to be an area designated around it as a protected root zone. The smallest definition of a root zone would be the dripline or area beneath the branches. Another measurement for a protected root zone is that it should be 1-1/2 to 3 times further than the height of the tree. If you plant a small, immature tree, its branch dripline area might be no more than 10 feet in circumference; however, you said you wanted a large shade tree, and what do you expect that small tree to do? Grow, of course, and it's going to grow in all directions, above and below the ground level. One suggestion we saw was that trees be planted no closer than 10 feet from the house, depending on how big the tree and roots will grow; also, the advice was not to plant trees above or near a water or sewer line.

When it comes down to selecting a specific tree to plant, there are many variables: how quickly do you want the shade? how big will this tree grow in 5 years? 10 years? is there space on your property for that large a tree? This article, Trees for Shade, addresses many of those questions, along with information on planting and care of trees. Without knowing the size or orientation of your property, we can't really recommend specific trees for your purposes. However, we searched our Plant Database for trees for California, and here are four possibilities you might investigate.

Cupressus arizonica (Arizona cypress)

Fraxinus velutina (velvet ash)

Populus tremuloides (quaking aspen)

Pinus contorta (lodgepole pine)

Cupressus arizonica

Fraxinus velutina

Populus tremuloides