Tomatoes grow best over the summer, when the temperatures are highest and conditions are often driest. They require plenty of water, approximately 1 to 2 inches a week. They do not tolerate dry soil and lack of water leads to fruiting problems or plant death. Fortunately, there are ways to make the most of the water you provide the plant so it may need less frequent watering. This is especially a concern if you live somewhere with water restrictions.
Lay a 3- to 5-inch layer of compost over the garden bed before planting. Till it in to a 12-inch depth with a power tiller. Compost adds organic matter to the soil, which helps retain moisture without becoming soggy.
Lay black or red plastic mulch over the garden bed before planting. Anchor the edges of the mulch down with soil, then cut a 3- to 6-inch hole for each tomato plant you are sowing. Plastic mulch retains moisture in the soil while preventing weeds, leading to less water evaporation.
Apply a 2- to 3-inch layer of organic mulch over the garden bed, such as straw or wood mulch, if the bed isn't plastic-mulched. Organic mulch also preserves soil moisture.
Lay down drip irrigation hoses along each row, setting them to deliver water directly to the base of each tomato plant. Drip irrigation delivers water directly to the soil, so less is lost to evaporation. Avoid watering the leaves of the tomatoes and only water the soil directly above the roots.
Water deeply once a week, instead of daily shallow watering. Irrigate in the early morning so the water has a chance to penetrate into the soil instead of evaporating under the afternoon sun.