Thirty-six Hibiscus L. species were grown for 20 weeks under three lighting treatments at 15, 20, or 25 ± 1.5 °C air temperature to identify flowering requirements for each species. In addition, species were subjectively evaluated to identify those species with potential ornamental significance based on flower characteristics and plant form. Lighting treatments were 9 hour ambient light (St. Paul, Minn., November to May, 45 °N), ambient light plus a night interruption using incandescent lamps (2 μmol·m-2·s-1; 2200 to 0200 hr), or ambient light plus 24-hour supplemental lighting from high-pressure sodium lamps (100 μmol·m-2·s-1). Five day-neutral, six obligate short-day, six facultative short-day, three obligate long-day, and one facultative long-day species were identified. Fifteen species did not flower. Temperature and lighting treatments interacted to affect leaf number below the first flower and/or flower diameter on some species. Hibiscus acetosella Welw. ex Hiern, H. cisplatinus St.-Hil., H. radiatus Cav., and H. trionum L. were selected as potential new commercially significant ornamental species.
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