Liquid smoke is a by-product of the lignocellulosic pyrolysis process and has long been used for various purposes, including as a plant growth stimulant. The use of liquid smoke for the growth of medicinal plants, especially Orthosiphon aristatus (Blume) Miq., is yet to be widely carried out. This study aimed to determine the effect of liquid smoke concentration on the phytotoxicity of cat whiskers, the growth response of cat whiskers in a wick hydroponic system for sustainable production practices, and the phenol and acetic acid contents in the liquid smoke solution. The measured growth response parameters included leaf, stem, root, total biomass, plant height, root length, stem diameter, and sinensetin levels. This study used liquid smoke collected using the stratification technique at 200 ⁰C and 400 ⁰C from three raw waste materials: pine wood, teak wood, and bamboo. The concentrations of liquid smoke in the hydroponic solution media were 0.25%, 0.5%, 1%, and 2%. The results showed that liquid smoke at 400 ℃ and concentrations of ≥3% caused significant phytotoxicity, including leaf wilting, necrosis, chlorosis, and plant death, owing high phenol and acetic acid levels. Furthermore, Andong bamboo liquid smoke (ABLS) at a concentration of 0.25% collected at 200 ⁰C generally gave better results for the growth of the cat whiskers plant on hydroponics. It increased sinensetin content compared to the control and other treatments. These findings suggest that stratifying pyrolysis temperatures and properly diluting liquid smoke can be used as growth stimulants while minimizing phytotoxicity.