Make the most out of limited rainfall in the arid Southwest with these landscape techniques.
In the arid Southwest, rainfall is scarce and evapotranspiration ( ETo ) 1 rates are high. In Tucson the average historical ETo rate is approximately 77 inches and average rainfall is 11 inches, in Phoenix average historical ETo is approximately 80 inches and average rain is 10 inches. For Tucson, this is a 7:1 ratio between water that is evapotranspired and what is available from rainfall, for Phoenix the ratio is 8:1. Only natives and some desert-adapted plants (plants from other desert areas that can flourish in our soils and our climate) can live on 10 or 11 inches of annual rainfall. Other desert-adapted plants may require some supplemental irrigation. Plants from non-arid climates require a great deal of supplemental irrigation. (1998) University of Arizona publication.