First Outside Grow in midwest (With pics)

Hey guys this is my first time posting on this site im new to it but i just have some problems that I need some help with. This is my first grow that I have been actually spendin time with them and putting lots of effort into them so I really don't want lose them now. They were beans from a bag of some really dank nugs and right now they are 3 months old. They have been doing really really good and looked great up until now. :sadcrying
About 1 to 1 1/2 weeks ago the leaves started turning yellow more towards the bottom at first but now it is starting to work its way up them. And right now i dont have any pics of the yellowing but tomorrow i will post them too. I just really need some help asap right now worried im gonnalose my babies. :sadcrying
So if anyone has any ideas what it could be please let me know. Thanks :jointsmile:
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looks good. the plants are using up the nitrogen in the potted soil. I would continue feeding with bloom specific nutrients and worry not about the yellow leaves. That is normal.

K I have just been using a miracle grow blooming fert. But was also wondering how will I know when it is time to harvest them also...