<![CDATA[The four o'clock flower is one of many plants whose blooming time is influenced by photoperiodism. Long photoperiods can inhibit the initiation of flowering and slow down the development of flower primordia, leading to delayed blooming. This study aims to examine the photoperiodic response of four o'clock flowers (Mirabilis jalapa L.) to shorter durations of sunlight exposure. The research was conducted over one month (September–October 2024), with data collection carried out in Jalan Setia Budi, Tanjung Rejo District, Medan, from 5:00 AM to 10:00 PM. The study involved observing plants growing in the same location to record the blooming times of the flowers. The data were analyzed descriptively and qualitatively, supported by literature reviews. The results indicated that Mirabilis jalapa L. plants under three different conditions—normal, complete darkness, and extreme conditions—showed slight variations in blooming times despite minor differences. On average, the flowers took 10 hours and 42 minutes to bloom. This suggests that minor environmental differences or specific plant factors may influence blooming times. Further research is recommended to include flowers of various colors, such as white, red, and mixed hues, as well as to expand the study to villages with different altitudes to gain a deeper understanding of the effects of photoperiodism. As a member of the Nyctaginaceae family and Centrospermae order, the four o'clock flower (Mirabilis jalapa L.) is an adaptive plant that grows easily in home gardens with minimal care, making it an ideal subject for studies of this nature.]]>
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