July 4, 2009

1 - There are options if a tree is too close to a house.

Yard and Garden July 4, 2009


I have a question about an ash tree that was planted about 3 years ago near our house. It is 10 ft. away from the foundation. The circumference of the tree is currently 12 in. (about 12 inches from the ground). A landscaper was concerned that we had planted the tree too close to the house. It is also about 12 ft. away from our septic system. If we needed to remove it, what would you suggest?

- Jeannie K.


The tree is quite close to the house. Removing it may be a wise thing to do. Your concerns should be about the branches damaging the roof and the potential for damage if the tree falls on the house in a wind storm. Root issues are also a consideration, but this may not be as great a problem as you are thinking. Significant root development will not occur under the house unless there is a leak in the plumbing, the soil around the house is overwatered (allowing seepage under the house), or if the house is on a slope with water flowing underground under the house. Roots cannot grow in dry soil, so unless there is some source of water under the house it is unlikely that roots will grow under the house. This is one of our benefits from our arid environment (moist climate locations do not have this benefit). When houses are built, there is often a deep footer surrounding the foundation, in the absence of water, roots are unlikely to grow under the footer and under the house. Thus, root damage is less likely than damage from the above ground portions of the tree. The septic system is another, major, concern. The tree is close enough to be a possible problem for the septic system. Your tree seems to be growing quite vigorously, so I wonder if it is already into the septic system.

If you do decide to remove and replace the tree, consider a smaller tree. The extent of the root system is usually related to the size of the tree. Roots can extend to 4 or more times the height of the tree away from the tree, so smaller trees will have a less extensive root system. There are some other considerations such as species (junipers tend to have roots spreading more widely than the "rule of thumb" given above). Some replacement trees to consider are flowering trees such as flowering crabapples, hawthorn trees (many have vicious thorns), and redbud trees. Chinese pistache (can have excellent fall color in some regions of New Mexico) and other smaller shade trees can also be used in a more confined location. If shade for the house is an important concern, you can consider a large trellis and vines planted several feet from your house instead of a tree. Vines grow quite rapidly and a well-constructed trellis should provide adequate support. I have seen this architectural feature used to shade a house. A high free-standing wall about 5 feet from the house shaded the house. This wall had windows positioned so that they provided views from the windows of the house. A trellis and vine system can be built (and vines pruned) to provide windows to allow views from house windows, yet shade for the house. There are many vines to consider: grapes, trumpet vine (vigorous and invasive), honeysuckle (not as invasive in New Mexico as in other regions), silver lace vine, and other vines of your choice.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.


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