That entirely depends on the plant. Some plants have adapted to grow in wetlands and need to have their roots constantly submerged in water. Succulents (cacti) may prefer to go weeks without water....
Tomato plants that are planted in the garden should have a minimum of 1" of water per week. If the plant is growing in a container it should have at least 1 gallon of water per day.
Water your tomato plants when 1'' of soil is dry. You stick your finger in and if it feels dry 1'', then it is time to water them.Tomatos like misture but do not like being flooded with water.Too...