I've had my plant in 12/12 from seed. 9am to 9 pm. I want to Change it to 5am to 5pm. How can I do this just a longer dark hour one night?
Id rather give it the extra few hours of light. Ive been testing with varying lighting schedules with some of my flowering plants. Its not 12/12, I took the timer out and do it when I can as close as I can. Sometimes I am 4 to 6 hours off (frequently). It started 7 to 7 its now 11 to 11 but its been all the times in between. My plant still flowered when it should have and is very comparable to other plants that are on a strict light schedule. Just about everyone would argue with me but I am finding strict scheduling isnt amazingly important as I used to think it was. yeah you need less daylight to induce flowering but I dont think it has to be 12/12 continually to get optimal results. Id just turn it off at 9pm one night and turn her back on at 0500 and let her run until 5pm. (or vice versa, turn on at 9pm and off at 0500 starting your new schedule) You could do it the dark route too I just am a fan of light = growth
Key piece of information missing: is it flowering yet? You can do this in a single change, as follows: While in veg, change your hours by extending light or shortening dark, never by lengthening dark. While in flower, change your hours by extending dark or shortening light, never by lengthening light.