Can i extend the lights out time to change my on and off times with out harming them?

[Errly]

Ok so I'm approaching summer and the days are getting hot, I have my lights on at 9am to 9pm but I want to now change it where the lights are on during the night. Any suggestions of how I can safely change the times so I don't mess with the grow cycle too much where it could hermy? Any help pls

 

[Moe.Red]

Just do it all at once. You won't hurt them too bad. But extend the night, not the day portion. So after 9:00PM, lights out, change the timer to come back on at 9:00PM and off at 9:00AM.

If they hermie from that, there is something else going on.