Possible photoperiods?

I am 99.99% sure that these are autoflowers!!! Photoperiod plants do not strech before switching them to a 12/12 light schedule. Autoflowers do!!!

Can we please get away from telling ppl you know something “100%” for sure when that’s just not factual. It has not FOR SURE initiated flower yet and is under 18/6. It IS indeed possible that it is a photoperiod. Let’s not speak in absolutes so regularly. That said. I see stigmas showing on the 2 in question. This can happen with photos as a sign of sexual maturity. If those begin to cluster into several stigmas/pistils per site - it’s likely initiated flower. This should happen within the next 2 weeks without much doubt.

That is not tough to say... All your 3 plants started to strech already. That is what cannabis does just before flowering. For that reason I am 100% sure that they are all 3 autoflowers when you left the light on 18/6 schedule. I used to run mother plants for clones and they are photoperiod. As long as you do not switch photoperiods to a 12/12 light schedule they do not start to strech! Soon they will all 3 start to make big buds!

That's tough to say but since you tell us the strain is "under development" it would seem to suggest that they haven't gotten it down quite yet and you probably DO have two photos and an auto - the one plant is REALLY in flower and looking good! Flipping to 12/12 would help to determine if that's so BUT the auto is not going to perform well under 12/12 so if you have another way of doing that - another tent perhaps? - that would be the best scenario. Do you have a warm closet you could stick those two in for their 12 hour period of darkness? As long as the temperature difference isn't TOO great (more than 10 degrees difference might be problematic), it would at least answer the question... And then, if they show themselves to be photos, you'd probably have to make a choice as to what you're going to grow - the auto or the photos... that is, if you don't have two tents and two lights... Good luck!