When your one-finger test says the soil needs water, apply the water long and slow and deep. When people lightly spritz an area, with “making the surface turn brown” as their guide, the water does not penetrate to the root zone where water is needed. Plants are trained to put out surface roots to capture the water, and plants trained this way are far less tolerant of drought and heat conditions. Instead, train your plant roots to dive deep into the earth to get water. Apply the water slowly to the surface of the soil, and allow time for it to soak in deeply. Apply adequate water to moisten the deeper layers of your soil, rather than merely the surface ¼ inch. In many cases, using this technique will result in you needing to water your garden much less often.
John Jeavons refers to a "3 second shiny." That means after you water a well-prepared garden bed, you water until the soil has a shiny layer of excess water which disappears within 1/2 to 3 seconds after watering stops. This is a guideline for a well-prepared bed, and might not be applicable for new gardens or places with tough garden soil issues. Again, ongoing applications of chunky high-organic-material compost will eventually gain you a well-prepared bed.
