Which of the following is essential for third-party verification in sustainable landscaping?

Sub-metering for irrigation is essential for third-party verification in sustainable landscaping because it allows for precise measurement and monitoring of water usage in landscaped areas. This capability is vital for assessing the efficiency of irrigation systems, determining whether the water is being used sustainably, and ensuring compliance with the water conservation goals that are often part of sustainable landscaping practices.

By using sub-metering, it becomes possible to track actual water consumption, which can then be compared to benchmarks or expected usage. This process helps verify whether the landscaping practices implemented are effective in minimizing water waste and aligning with sustainability criteria. Furthermore, it provides quantifiable data that can be utilized during third-party audits to ensure adherence to LEED certification standards.

While maintenance contracts, soil testing results, and plant growth monitoring are all important elements of landscaping, they do not directly contribute to the third-party verification process in the same way that accurate water usage measurement does. Each of these other factors can support sustainable landscaping efforts but does not serve the specific function of verifying water management practices.