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Monday - June 28, 2010

From: California City, CA
Region: California
Topic: Non-Natives, Septic Systems, Grasses or Grass-like
Title: Non-native smoketree for California City, CA
Answered by: Barbara Medford

QUESTION:

I was wondering if you could tell me if it would be a good or bad idea to plant a Smoke Tree (most likely European) in the vicinity of a septic tank. We are looking for something which will provide a moderate amount of privacy, since we live in the middle of the desert, and have very few neighbors. We are also considering Cordylines as an scattered around the smoke tree. Any help that you would be able to provide would be greatly appreciated. Thanks in advance. Ian Kelly

ANSWER:

Sadly, you have presented Mr. Smarty Plants with several ideas he considers bad. First, you should never plant a woody plant, like a tree or shrub, over a septic system. Those woody roots underground are larger than the tree visible aboveground, and relentless in their progress. They can lift sidewalks, crack foundations and certainly play havoc with a septic system. Our recommendation for use over septic systems is always grasses native to the area. Their long fibrous roots will hold the soil, draw up some of the moisture in the septic lines, but will not interfere with them.

Our second version of a bad idea is to plant the European smoke tree, Cotinus coggyria, (from Floridata) which is native to southern Europe, central Asia and the Himalayas. The Lady Bird Johnson Willdflower Center is dedicated to the growth, protection and propagation of plants native not only to North America, but to the area in which that plant is being grown.

And, in spite of it being native to North America, we don't think it's a good idea to try to plant Cotinus obovatus (American smoketree), in your location in the Fremont Valley of the Mojave Desert. Although both the native and non-native smoketrees are listed as being viable in USDA Hardiness Zones 5 to 8, and your area on the eastern border of Kern County is Zones 8a to 9b, it still is a long way from the nearest area where either of them is believed to grow. A few counties in Central Texas are shown on the USDA Plant Profile as having the American smoketree growing, that is as far west as they go. The European smoke tree grows in the East and north up into Canada.

Both of these trees are relatively rare in trade and difficult to transplant. Since you should not plant it over your septic system anyway, why waste your time and effort over a tree that will probably not survive there?

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