How to water pots The most effective way to water small to medium pots is to dunk them in a bucket of water. Add seaweed to the water as a plant tonic. Hold the pot under the surface until all the bubbles stop. The soil is now thoroughly wet. Don't let pots sit in water longer than a couple of hours. During the warmer months, all indoor plants will need watering about twice a week. Remember to always check the soil moisture with your finger prior to watering. Never water a already wet plant.