Stevia ovata Willd. is an invasive weed that has become naturalised in northern Queensland, Australia. To aid management of current infestations, this study evaluated seed germination under a range of constant (13−48°C) and alternating (11/7 to 52/42°C) temperature regimes and quantified the potential longevity of soil seed banks. The effect of different soil types, levels of pasture cover and burial depths on seed longevity was investigated in both the dry- and wet-tropics of North Queensland. Germination of S. ovata occurred under a wide range of both constant (13−39°C) and alternating day/night temperatures (16/12 to 52/42°C), but optimum conditions ranged between 24 and 27°C and 24/20 and 37/31°C respectively. As temperatures declined below the optimum, an increasing proportion of seeds went into a state of enforced dormancy. In contrast, higher than optimum temperatures caused a proportion of seeds to lose viability. Differential responses in seed longevity of S. ovata occurred between the two experimental sites. In the wet-tropics, seed viability was