In contrast, for browalia (Browalia speciosa Hook.) and angelonia (Angelonia augustifolia Benth.), both of tropical origin, the estimated Tmin was 8.9and 9.9◦C, respectively (Blanchard, 2009). Breeding efforts have introduced desirable traits such as early flowering, frost tolerance,and heat tolerance. Therefore, depending on the breeding objective, cultivars of the same species may have different Tmin and Topt values, as well as thermal time, for a particular event such as flower-ing. For example, the calculated Tmin for petunia (Petunia × hybridaVilm.-Andr.) ‘Dreams Neon Rose’ was 2.7◦C lower than that of ‘Wave Purple Classic’ (Blanchard, 2009)