Certified Professional Horticulturist (CPH) Practice Exam

What is the purpose of mulching in landscaping?

1. To enhance soil drainage

2. To suppress weed growth

3. To increase plant growth rate

4. To improve soil texture

The correct answer is: To suppress weed growth

Mulching serves a fundamental role in landscaping, particularly in suppressing weed growth. When a layer of organic or inorganic material is applied to the surface of the soil, it acts as a barrier to light, which is essential for the germination of many weed seeds. By reducing light exposure, mulch helps to limit the establishment and growth of weeds, thereby minimizing competition for nutrients, water, and light with desired plants. Additionally, while mulching can have benefits related to soil drainage, plant growth rates, and soil texture, those aspects are secondary to the primary function of weed suppression. For instance, a well-chosen mulch can retain moisture and regulate soil temperature, which indirectly aids plant health and growth, but the immediate and most recognized benefit is the control of weed populations. This not only makes maintenance easier for gardeners and landscapers but also contributes to the overall health of the garden or landscape by promoting better growing conditions for cultivated plants.