Tips for Watering during a Heatwave. During a heat wave, it’s crucial to water plants effectively to prevent them from wilting or drying out. Water deeply and less frequently, focusing on the soil rather than the leaves, ideally in the early morning or late evening to minimize evaporation. Consider using soaker hoses or drip irrigation, and adding mulch to help retain moisture. Avoid Overhead Watering. Sprinklers that spray water on the leaves can cause leaf burn and are less efficient