Certified Professional Horticulturist (CPH) Practice Exam

How should one properly water the lawn?

1. Irrigate soil to depth of 4-6 inches

2. Apply light application of water

3. Water only the driest areas

4. Water during the middle of the day

The correct answer is: Irrigate soil to depth of 4-6 inches

Watering the lawn effectively involves ensuring that moisture penetrates deep into the soil, which fosters healthy root development and improves drought resistance. The correct depth to aim for is typically around 4-6 inches; this allows moisture to reach the deeper roots, promoting robust growth and a resilient lawn. When soil is watered to this appropriate depth, it encourages deep rooting as grass seeks moisture below the surface. Shallow watering, on the other hand, can lead to weak root systems that are more susceptible to heat, drought, and disease. This method creates a more sustainable lawn care practice since deep roots help the grass to access water more efficiently over time. In contrast, applying light applications of water may only wet the top layer of soil, leading to evaporation and ineffective moisture retention. Watering only the driest areas can result in uneven moisture distribution and can exacerbate potential dry spots. Finally, watering during the middle of the day is generally not recommended because of higher evaporation rates that occur from heat and sunlight, which means less water reaches the soil where it is needed. Focusing on deep and thorough watering promotes a healthy, green lawn that can withstand varying weather conditions.