Knowing how often to water is crucial for plant health, and the answer differs dramatically between planter boxes and in-ground gardens. The core principle is that plants in containers dry out much faster and require more frequent attention than those planted directly in the earth.
Plants in planter boxes have a limited volume of soil, which means less water retention and quicker drying from sun and wind. Their roots are confined and cannot seek out deeper moisture. As a result, you might need to water container plants daily during hot, dry, or windy weather. The key is to check the soil regularly. Insert your finger about an inch deep. If it feels dry, it's time to water thoroughly until you see water drain from the bottom holes, ensuring the entire root ball is moistened.
In contrast, plants in the ground benefit from a vast reservoir of soil that holds moisture longer and provides more stable conditions. Their roots can grow deep to access water. Therefore, established in-ground plants typically require less frequent but deeper watering. A general rule is to provide about one inch of water per week, either from rainfall or irrigation. This encourages deep root growth. Watering deeply once or twice a week is often better than light, daily sprinklings.
Your specific schedule will always depend on factors like plant type, climate, season, and soil composition. Always let the soil's moisture level—not the calendar—be your primary guide. For both containers and gardens, morning watering is ideal to reduce evaporation and allow foliage to dry, helping prevent disease.