Generally, sandy, well-drained soils need to be watered twice a week, while heavier clay or loamy soils that hold moisture may only need to be watered once per week. In hot weather, it is recommended to irrigate for 20-30 minutes per day, allowing the water to penetrate the soil completely. A good general guideline is an inch of water per week either by rain or watering; in arid climates, it is double that