We investigated the effects of photoperiods (6-, 9-, 12-, or 24-h) on the vegetative growth, flowering and fruiting of two Capsicum frutescens L. lines from the Bonin and Ryukyu islands in Japan and C. annuum cv. ‘Takanotsume’ (referred to as BON, RYU, and TK, respectively). BON, RYU, and TK plants had better vegetative growth as photoperiod lengthened; plants were taller, and the dry weight of shoots and roots was greater. The leaf area of TK was not affected by photoperiod, whereas the leaf areas of BON and RYU were smaller when grown under a 24-h photoperiod than under a 12-h photoperiod because leaf abscission occurred sooner under a 24-h photoperiod. TK also had better reproductive growth as the photoperiod lengthened; flowers and fruits were more numerous, the fresh and dry weights of fruits were greater, and the percentage of fruit set was higher. Under a 24-h photoperiod, however, the flower bud development of BON and RYU was initially not observed. BON finally flowered under a 24-h photoperiod, but RYU did not. These results suggest that BON and RYU responded photoperiods more strictly than TK and there may be various responses to photoperiods in flowering and fruiting among lines of C. frutescens.