Cleome and Polanisia germination is non-uniform, requiring plug growers to continuously manipulate germination conditions. Germination and yield potentials remain significantly lower than bedding plant standards. However, cleomes have been reported to germinate prolifically in gardens, escape cultivation and naturalize. The overarching objective was to compare germination of Cleome and Polanisia seed lots in response to planting depth, stratification, temperature and photoperiod regimes that simulate field and greenhouse conditions. Three experiments were conducted. First, field germination of P. dodecandra fresh and one-year-old seed (0, 1 cm below soil surface) was evaluated (Expt. 1). Second, the effect of stratification (0, 3, 6, 9, 12 weeks at 4°C), photoperiod (0/24, 12/12 and 14/10 h light/dark) and temperature (21/17°C and 19/15°C day/night) regimes on P. dodecandra germination were studied (Expt. 2). Third, the effect of stratification (0, 6 weeks), photoperiod (0/24, 12/12, 14/10 h light/dark) and temperature (21/17°C, 19/15°C) on germination of 11 seed lots of Polanisia and Cleome were compared (Expt. 3). In Expt. 1, buried seeds had significantly greater germination (66%) than non-buried (5%). In Expt. 2, higher germination was observed in stratified seeds (16%) incubated in complete darkness (35%) and at warmer temperature regimes (21%). Expt. 3 confirmed these findings with greater germination in darkness (32%) and warmer temperature (41%), but the effect of stratification varied among seed lots. Significant three-way interactions among seed lot×age×depth (Expt. 1), duration of stratification×temperature×photoperiod (Expt. 2) and seed lot (Expt. 3) confirms lack of uniformity in commercial production and may contribute to spread in non-cultivated environments.