Certified Professional Horticulturist (CPH) Practice Exam 2025 - Free Horticulturist Practice Questions and Study Guide

Organic mulch is highly regarded for its benefits in weed control. This type of mulch, which includes materials such as wood chips, straw, shredded leaves, and grass clippings, effectively suppresses weeds by blocking sunlight, thereby preventing weed seeds from germinating. Additionally, as organic mulch decomposes over time, it enriches the soil with nutrients, enhancing overall soil health and promoting the growth of desirable plants.

In comparison, rubber mulch and rock mulch may provide some degree of weed suppression; however, they do not offer the additional benefits of improving soil quality as they do not decompose. Landscape fabric can control weeds effectively by creating a barrier; however, it can become less effective over time as soil and organic matter accumulate on top of it, allowing weeds to take root. Thus, organic mulch stands out not only for its immediate weed control benefits but also for its long-term positive impacts on soil ecology and plant growth.