A rain gauge for garden watering is useful only when it measures rain that can realistically reach the growing area and when that number is checked against actual soil moisture. A gauge under a tree, beside a roof edge, or inside sprinkler spray can give a misleading reading even when the scale itself is easy
A garden water target stated in inches describes depth across an area, not a fixed number of gallons. A useful starting calculation is garden area in square feet multiplied by target water depth in inches multiplied by 0.623 gallons. Rainfall can reduce that irrigation amount, but only when enough of it reaches and moistens the
Garden watering frequency works better as a check-and-adjust routine than as a fixed calendar. Soil moisture, recent rainfall, soil texture, mulch, root depth, plant establishment, and current weather all change how soon a garden needs water again. A useful starting schedule should therefore tell you when to check the soil, not automatically when to turn