Agriculture accounts for roughly 70% of global freshwater withdrawals, creating strong demand for plant-centered irrigation methods that detect water stress earlier and use water more efficiently. Plants under drought emit airborne ultrasonic sounds, but most prior studies treat these emissions only as diagnostic outputs. This study tests a closed-loop concept in which drought-associated plant acoustics are first decoded and then reused as biologically informed ultrasonic stimulation. In Phase 1, Ixora plants were recorded with a SONAPHONE system at 1 h and 9 h after watering. Well-watered plants showed sparse, short pulses (~7 ms) with dominant frequencies above 50 kHz, whereas early-drought signals were denser, longer (~16 ms), and lower in frequency. Across the analyzed drought spike set (n = 12), mean pulse width was 16.36 ms, mean amplitude 27.25 dB, and mean dominant frequency was 25.86 kHz. In Phase 2, well-watered Ixora leaves were exposed to 22 kHz or 30 kHz ultrasound for 20 min within a 1 h trial; controls received no ultrasound. Infrared thermography measured leaf temperature change (ΔT) as a non-contact proxy consistent with stomatal-linked evaporative cooling. Mean ΔT increased from 1.00 ± 0.23°C in controls (n = 6) to 2.07 ± 0.31°C at 22 kHz (n = 3) and 1.73 ± 0.21°C at 30 kHz (n = 3). These findings support a proof-of-concept precision-irrigation framework in which plants are both sensors and responsive biological systems within an irrigation feedback loop.