Tomato plants can be grown indoors or outdoors, but either way they like a lot of water. Depending on climate and geography, some will need to be watered more often then others. Without enough water, tomato plants will shrivel up and die. On the other hand, with too much water they can become susceptible to disease. Watering tomato plants with sprinklers is not acceptable because it promotes disease and insect infestation. In addition, the time of day, the temperature and the amount of water are all important.
Water new tomato plants deeply and thoroughly with a garden hose after they are planted. Let the soil dry out for a day or two. Feel the soil. Once it is dry about 1 inch down, water it again.
Lay out a soaker hose near the tomato plant stem, keeping a space of about 1 inch between the stem and the hose.
Turn the faucet's spigot until water is slowly dripping from all holes in the soaker hose. Keep the water running until the tomato plant is soaked at least 3 inches below the soil's surface. This could take from a half-hour to a couple of hours.
Water your tomato plants in the cool hours of the morning so less water evaporates. This is especially beneficial for hotter regions, such as the Southwest and South.
Water your tomato plants deeply every two days on average or when the soil is moderately dry.