Overhead sprinklers are the easiest way to cover large expanses, but they’re inefficient, losing up to half the water to evaporation. Trees are better served by watering methods that apply water slowly, right at soil level. It may take several hours to properly water a single mature tree. A soaker hose applies water slowly so it soaks in rather than running off. Soaker hoses are an efficient way to water trees because they’re porous and release water slowly. Encircle a tree with a spiral of soaker hose and run it for an hour or more — as long as it takes for water to penetrate 6″ or 8″, using the screwdriver test.