MadSci Network: Botany |
Some plants do require daily darkness to grow normally. For example, tomato plants receiving 24 hours per day of light get lesions on their leaves. Other plants, such as some houseplants, seem to grow fine with continuous electric light. Some plants require a daily light period (photoperiod) of less than a certain number of hours in order for them to produce flowers. These are called short day plants. Short day plants, such as chrysanthemum and poinsettia, would certainly require some daily darkness in order to be able to produce flowers. Reference Photoperiodism
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