What lies beneath a tree is just as important -- if not more so -- than what grows above. Tree roots stabilize and feed the tree, and if they are damaged by yard tools, the tree can suffer. Tree roots can also cause damage of their own, when they break through concrete sidewalks or damage underground pipes. It's the latter you might need to worry about when it comes to cedar trees (Cedrus spp.), as they have deep roots.
Below the Soil
Environmental conditions help determine how deep tree roots go. Even if a tree tends to develop deep roots naturally -- like the cedar -- it won't do so if the roots have nowhere to go. Hard, packed, dry soil will prevent trees from developing deep, sturdy roots. In ideal conditions, trees have been known to develop roots down to 20 feet below the surface of the soil, but in most cases, the deepest roots are 6 to 7 feet down.
Although some trees have the word "cedar" in their name, true cedars are members of the Cedrus family. Most of them reach their maximum sizes rather slowly -- giving them ample time to develop deep roots. In general, cedar trees grow in U.S. Department of Agriculture plant hardiness zones 6 through 9, although this can vary by species and cultivar.
Choosing a Spot
True cedars need plenty of room to spread out -- at least 6 feet of space around the tree. Some species spread their branches to 50 feet or more. Because of the tree's deep roots, you don't have to worry about surface roots invading the lawn or lifting your driveway, as as long as the tree has room to grow horizontally, go ahead and plant it near your lawn. Keep it well away from underground sewer lines or other underground structures.
Other than plenty of space, the most important thing cedar trees need is rich, deep soil to develop those deep roots. Shallow, poorly draining or compact soil will result in poor growth, which can weaken the tree and even cause it to topple later in life. Cedar trees also do best in full sun and -- again because of their deep roots -- can tolerate drought conditions.