Shallow Tree Roots

80 to 85 % of a tree’s roots are found in the top 18″ of soil. Roots will be even more shallow in clay or compacted conditions.

The reason trees don’t root deeper because they need oxygen and moisture and nutrients to survive. Heavy clay soils, and soils compacted by traffic, have little air space, so roots must stay in the upper levels to have enough air, nutrients and moisture to survive.