So I’m starting my plants indoors, it’s march 21st, and moving them outdoors in May, June. The natural daylight hours outside here in southern Indiana are at 12h:14 min long, plus the civil twilight witch is 56 min witch makes it 13h:10 min long. I’m starting them Inside under led lights and following the outdoor photo period so when I move them outdoors they don’t go into light shock or revegetation. So is 13h:10 min long enough to start my seedlings on under a LED light indoors?
Or should I put the light on 18 hours to start the seedlings and slowly decrease the amount of light per day until I get back to the natural photo period outdoor?
I would keep doing what you are doing
Start at 18 hours and work your way down to daylight time outside.