Things are looking bad for the Wedding Cake plant. It refuses to look good, and no matter what I try the leaves that are turning yellow keep getting worse. It started a super early flower on that plant, and it already has several bud sites forming, mostly along the main stalk. The Northern Lights is also pissed, but not as mad as the Wedding Cake plant. The NL has mostly ceased growth either upwards or outwards, and it has super dense nodes that all stack on top of each other.
At this point I don't know what the issue could be for the plants. While the temperature and humidity were within the acceptable ranges for growing, I noticed the VPD was sitting around 1.2-1.3 for the first couple weeks, and after I saw the VPD hit 1.4 I bought a humidifier. The VPD sits around 1.0 now, and the leaves that haven't gone to shit on the plant look happier, but they still aren't growing at all.
I don't think it's a nutrient deficiency since the plants are only 21 days old at this point, but I'm not far from adding something to see what happens. If the Wedding Cake keeps getting uglier over the next couple days, I might give it a shot.
@bongbong, I ended up using a product called Recharge after visiting the local hydroponic store, and that seemed to help the Northern Lights plant a lot. Not much could be done about the one that went straight into flower. It's mostly a stick with a bud on top. These plants had a very stressful start between a transplant and changing from a cheap Chinese light to a proper one, and then they weren't watered properly while I was gone for Thanksgiving and Christmas.
I'd agree that a root problem was likely my issue. The Northern Lights plant is an auto, but it's just now starting to flower after 2 months. I'm hoping I can give it proper care over its flower cycle and get a reasonable harvest from it.