Lay a soaker or drip hose between each planned planting row. Water doesn't soak through plastic mulch, necessitating irrigation beneath the mulch layer.
Lay the black plastic over the top of the garden bed and irrigation hoses. Weight the edges of the plastic with rocks or a soil mound so it doesn't blow up during windy conditions.
Cut 3- to 4-inch-diameter planting holes in the plastic for each cantaloupe seedling. Space the holes 2 feet apart along each row, setting the rows 5 feet apart.
Plant the cantaloupe seedlings into the mulch holes once all danger of frost is passed and after the soil beneath the mulch warms to a minimum temperature of 65 degrees Fahrenheit.
Inspect the mulch after rain. Poke small holes through the plastic in any areas that collect puddles of standing water. The holes allow the rain water to drain through the plastic and into the soil below, where the moisture can benefit the cantaloupes.