Tomato Irrigation

Irrigation Amounts

• Tomatoes need 1 to 2 inches of water each week, depending on the type of soil and how hot the weather is. If it rains, tomato plants might not need supplemental irrigation, but they usually need regular waterings during dry summer months.

  Experts at the National Gardening Association and the University of Florida Institute of Food and Agricultural Sciences recommend watering tomatoes about an inch each week during moderately warm weather and closer to 2 inches during the hottest and driest parts of summer. Sandy soils with quick drainage also require more water than heavier soils. If the plants start to wilt and the soil feels dry to the touch, they probably need more water. To provide an inch of water, use about 60 gallons for every 100 square feet of garden space.

Watering Frequency

• Water tomato plants at least once every 10 days. The National Gardening Association recommends letting the soil dry out somewhat between waterings, because tomatoes do not grow well when they sit in overly wet soil. Its experts also suggest watering once every four or five days for sandy soils and once every week or so for heavier soils.

Irrigation Time

• Water tomato plants in the morning for the most efficient use of water. Cool morning temperatures mean that water has more time to soak into the soil and be absorbed by plant roots before it evaporates. Watering in the morning keeps plants healthier than watering at night, because diseases can develop when plants stay wet overnight.

Irrigation Strategies

• Water soil deeply so that the water soaks into the soil to depths of at least 6 to 8 inches. Deep waterings help plants develop strong and deep root systems. Deep waterings also mean less frequent watering sessions for the gardener. Do not water tomato plants if the soil is already wet, because tomatoes do not grow well with excessive irrigation.

Mulching

• The World Vegetable Center and the National Gardening Association recommend applying a layer of mulch around the base of tomato plants to help them retain an even amount of moisture in the soil. In lieu of commercial mulch from a gardening store, try using a 2- to 4-inch layer of grass clippings or straw.