If you have ever wished your plants could tell you when they need water, you may not be paying close enough attention to the clues in the soil around your plants. The key to keeping your outdoor plants adequately hydrated lies in attentive observation. As you go through the growing season, check moisture levels in outdoor plants daily to assess their growing conditions. Observe your outdoor plants every day, and as you learn to check the soil around your plants, you will know that they are getting adequate hydration.
Lift the plants you grow in containers every day to assess how heavy the containers feel. If the containers feel especially light, the soil inside the container is dry. Provide a thorough watering for these plants immediately until water runs out the drainage holes underneath the containers. Lift the plants in the containers again after you water them so you can learn how heavy the container feels when the soil is properly moist. If a container feels heavy when you lift it, the plant does not need water.
Insert your finger to the second knuckle into the soil around plants that are growing in the ground. Pull your finger back out of the soil and examine it. If your finger has moist soil stuck to it, the soil is moist enough, and the plant does not need water. If your finger is free of moist soil, the soil needs water immediately. Provide a thorough watering to the soil around the plant--avoid spraying the foliage because this can contribute to plant disease.
Assess the overall moisture level of your soil. This is particularly useful for checking moisture levels of grass. Pound a spade into the soil between 6 and 12 inches deep. Pull the spade back up and assess the soil that is clinging to the spade. If the soil is moist, there is no immediate need to water. If the soil is dry, provide water for the planting area.