Age

A plants growth rate is determined primarily by nutrition, hydration and light availability. Temps and humidity are secondary factors and unless either are extremely high or extremely low, have very little to do with real world growth rates. Going to 18/6 would be more plant friendly and is the optimum lighting schedule for cannabis, autos and photoperiod plants in veg. Plants do actually need to sleep and undertake certain metabolic processes at night that they can not do during "lights on time" and 3 hours of darkness may just not be enough. I like to think of the six hours of darkness as 2 hours to recover, 2 hours to rest and 2 hours to prepare for the day ahead and this is basically what plants do during the "lights off" cycle and just 3 hours is probably not enough for these things to occur. Otherwise your plants look healthy and should give you much joy over the coming weeks! Hope this helps,.............. Organoman.

Looks good to me growmie . But with no data it’s hard to give you advice. The best thing I can tell you is that a plant’s growth rate is determined by the relationship between humidity and temperature ... right now you should around 65/70% humidity and 24C , hope this helps ! 🚀