Population outbreaks and failures in controlling Tetranychus urticae Koch (Acari: Tetranychidae) were reported on ornamental plants in Miami-Dade County, Florida. We compared the susceptibility of two T. urticae field populations collected from commercial nurseries with a laboratory population to one new generation (cyflumetofen) and two conventional (abamectin and pyridaben) acaricides. The field populations were collected from hibiscus (Hibiscus rosa-sinensis, Malvaceae) and croton (Codiaeum variegatum, Euphorbiaceae). Resistance ratios based on LC50 values of the field and laboratory populations revealed high resistance levels to the two conventional acaricides (9.64 and 19.28-fold abamectin, 12.34 and 34.08-fold pyridaben), and low levels (1.88 and 2.39-fold) of cyflumetofen resistance in the hibiscus and the croton populations, respectively. Rotation of acaricides with different modes of action and biological control should be implemented to mitigate T. urticae resistance problems in ornamentals in south Florida.