Which ornamental feature might benefit most from supplemental irrigation?

Supplemental irrigation is especially beneficial for ornamental grasses because they thrive in a controlled moisture environment to achieve optimal growth and visual appeal. Ornamental grasses can be sensitive to drought conditions, particularly during their establishment phase or in periods of extended dry weather. Regular watering helps to support their growth, enhances their vibrant colors, and maintains their overall health and resilience.

In contrast, features like waterfalls, concrete pathways, and rock gardens do not have the same water requirements. Waterfalls are designed to recirculate water, so they don't require irrigation; they benefit from the water that feeds them through their system. Concrete pathways, being hardscapes, do not require any moisture for their functionality. Rock gardens typically consist of drought-resistant plants that thrive in well-drained conditions and do not benefit significantly from supplemental irrigation.

Overall, ornamental grasses specifically require more attentive watering practices to maintain their aesthetic qualities and health, making them the feature that benefits most from supplemental irrigation.