Check the zucchini bed's soil temperature with a soil thermometer. Wait for the soil to warm to 75 degrees Fahrenheit, and spread a 2- to 3-inch layer of mulch, such as grass clippings, straw or shredded leaves, on the zucchini bed. Mulch helps to conserve moisture, which makes watering more efficient. It also reduces weeds so zucchini plants have less competition for water.
Arrange a soaker hose throughout the zucchini bed if desired. Weave the soaker hose around and between plants, covering the entire root zone of each plant. Using a soaker hose in this way instead of watering with a garden hose makes watering easier and more efficient.
Place an empty, small, shallow dish or can, such as a tuna can, near one of the zucchini plants or underneath a hole in the soaker hose.
Turn on water in morning so it drips slowly if you use a soaker hose in the zucchini bed. Otherwise, water in morning near the base of the zucchini plants by using a traditional garden hose. Stop watering the site when water is 1 inch deep in the dish or can. Dump the dish or can where it was set, and put it back in place. Watering in morning allows the plant leaves to dry before nightfall.
Insert one of your fingers 1 inch deep in the garden's soil. If the soil feels dry at that depth, it's time to water the zucchini again. You'll probably need to irrigate zucchini one or two times each week during the entire growing season, depending on rainfall.