How Far Do Deodar Cedar Roots Go?

Deodar cedar trees (Cedrus Deodara) have silver-green foliage on graceful, drooping branches, making them a striking addition to a garden, lawn or landscape. They grow from 40 to 70 feet tall with a canopy spreading 30 to 40 feet wide and need a moderate amount of room for their roots to spread. They can be grown in U.S. Department of Agriculture plant hardiness zones 7 through 9.

Size and Root Spread

While a deodar cedar's height and the spread of its canopy varies, so does the spread of its roots. Larger trees have larger root systems. The roots of a mature deodar cedar spread up to 32 feet from its trunk.

Use and Roots

Deodar comes from a Sanskrit word meaning "timber of the gods," and these lovely trees have been successfully grown on lawns at least 6 feet wide, as screens, as residential street trees, in buffer strips around parking lots and on highway median strips. These uses all suggest that the spread of deodar cedar roots is not an issue in urban areas. Arborists at Cal Poly's Urban Forest Ecosystems Institute rate its potential for root damage as "moderate."

Root Spread

Arborists have traditionally accepted the general rule that roots extend about 1 1/2 times the height of the tree. More than 60 percent of the nutrient- and water-absorbing roots grow beyond the drip line or edge of the tree canopy. This guideline is typically used for urban tree root protection zones. Another rough formula is to measure the radius of the drip line and multiply by 5 to get an estimated radius of the root spread.

Root Depth

The general rule for estimating the depth of tree roots is that most of them grow in the top 18 inches of soil. How deep a deodar cedar roots will grow is based on its growing conditions. Tree roots rarely penetrate through urban sites that have compacted soil, poor drainage and dense layers of rock.