by Matt Gibson
Different types of tomato plants need different amounts of water to thrive, and how much water your tomatoes need and how often they should be watered can also vary depending on how large your plants have grown and the region in which you are gardening. Factors such as the presence of mulch can also alter a tomato plant’s water requirements. (Mulch locks moisture in, helping the soil to retain it longer to keep it available for plants.)
Baby tomato plants and seedlings are generally grown in seed trays or relatively small containers, so they will need to be watered the most frequently because their soil will dry out quickly. Check on these plants at least once per day to ensure the soil has not dried out, and lightly mist them with a spray bottle to keep the top of the soil moist. Be careful not to give small tomato plants like these too much water at a time. When seedlings start to need water more than once per day, more than likely it is time to either move them into larger containers or transplant them into the outdoor garden.
Tomatoes growing directly in the ground outdoors generally need one or two inches of water per week to thrive at the beginning of the growing season, and they prefer to receive this moisture in daily watering sessions that take place in the mornings. As the season progresses, the weather turns hotter and plants grow larger, meaning they begin needing more water than they did at first. When this occurs, garden tomatoes may need the gardener to water them twice daily. It’s best not to water plants during the hottest part of the day, so wait until temperatures fall a bit as afternoon turns into evening for your second watering session.
When tomato plants are grown in containers, the soil heats more quickly, leading it to evaporate faster than it does in the garden. That means tomato plants growing in a container garden need more water than tomato plants growing directly in the ground. Start by watering tomato plants in containers in the morning, giving them enough hydration that the water runs (not drips) from the drainage holes at the bottom of the container. Check on the plants again later in the day to see whether the soil still feels moist an inch under the surface, and if it is dry at a depth of an inch, water the plants again. For best results, don’t water your tomato plants when the summer sun is at its peak. Instead, wait until temperatures start to fall and afternoon becomes evening to water your plants if they need a second session. Like garden tomatoes, the hydration needs of tomatoes growing in containers is likely to increase as the season progresses.
Want to learn more about watering tomato plants?
University of Missouri Extension covers Growing Home Garden Tomatoes
University of Minnesota Extension covers Growing tomatoes in home gardens