|We are starting tomatoes from seeds indoors. Is it harmful to keep the fluorescent lights on 24 hours per day? Do plants really need a dark period?
|Although most experts recommend that you keep the lights on about 16 hours per day, I keep mine on for 24 hours per day when starting seedlings. So far, I haven't had any problems. I don't have a timer, and I have a feeling that if I turn them off at night, I won't remember to turn them on in the morning before I leave for work. If you were growing plants permanently under the lights--as opposed to seedlings that will get transplanted outdoors in a month or so--it might make more difference.