There is a growing interest in understanding the mechanisms involved in seed germination stimulated by smoke and smoke-derived compounds. In this study, we aimed to determine the possible role of gibberellins (GAs) and reactive oxygen species (ROS) in the seed germination of three smoke-responsive and fire-adapted species, viz. Onopordum caricum (Asteraceae), Sarcopoterium spinosum (Rosaceae), and Stachys cretica (Lamiaceae). We conducted four germination experiments using smoke water, karrikinolide (KAR₁), cyanohydrin mandelonitrile, gibberellic acid (GA₃), paclobutrazol, hydrogen peroxide, and several agents generating ROS at different concentrations. The three species had a positive germination response to KAR₁. Sarcopoterium spinosum seeds were also sensitive to mandelonitrile. Exogenous GA₃ promoted the germination of all KAR₁-responsive species in a concentration-specific way. Furthermore, GA biosynthesis was found to be required for the induction of germination by smoke water and KAR₁. Finally, ROS treatments stimulated the germination of KAR₁- and cyanohydrin-sensitive S. spinosum seeds, but not only KAR₁-sensitive O. caricum and S. cretica seeds. In conclusion, we showed that smoke-promoted germination is far more complex than previously believed and that future studies should be carried out using species with different sensitivities to smoke chemicals.