EARTH SCIENCE > LAND SURFACE > SOILS > SOIL ROOTING DEPTH
he distance in inches that plant roots extend into the soil. Knowing the
average root depth for the plants in each watering zone is important to
determine an efficient watering schedule. Shallow roots require more frequent
watering than deep roots, which can draw water from a larger soil profile.
Average root depths vary with plant type. Trees will have root depths of 24
inches or more. Xeriscape plants will have root depths around 10 inches. Shrubs
and perennials will have roots of 8 inches or more. Grass can have deep roots
(greater than 6 inches, depending on region). Annuals and bedding plants have
the shallowest roots at 4-5 inches.
Adapted from the Water Conservation Glossary.