Razberry Boogie Woogie

Soil is way too wet. It doesn't need or want shitloads of water right now. You can gently stand her up and with a chopstick or something and tie it, or backfill a little soil around her to help her stay upright. DON'T MIST IT. It's gonna damp off if you keep that stem where it meets the soil too moist. If that happens, it dead meat. It doesn't need fertilizer, just a little water and some full spectrum light. And make sure the light is something like a T-5 fluoressant or some other cool light. Keep it about 8" to 12" from the top of the seedling. Weak light or light to far away will create a stretchy leggy seedling that will fall over.

i would say no fill your space abit more withsome training and defoliation inmy opinion you will get alot more yield if you build a nice canopy :) it will make the most of your grow light and spread the light evenly over the flower sites of the plant look up defoliation and lst tecniques and youll get a really nice plant with a healthy yield that can keep you going though ultimatly this is your plant so do what you want hehe best of luck

I'd almost remove some leaves to help airflow in there. might be a bit to compact. I legit fold the branches into the net and try and fill out every square possible. 90-95%+ coverage is the goal. I have also trimmed off branches that just get in the way as when they flower they won't have airflow and that can lead to rot.

If not light damage, looks like a trace element sympton, which would be unlikely an dmore often caused by pH swings than physical availibility of any trace element (B in this case). easy to eliminate light damage as cause by where it is occurring and looking at the top few nodes/internodes.. if spacing is okay, it's probably not the light. If it is happening outside of teh top-most leaves, also unlikely it is the light, but a mobile nute issue would occur at the top initially, too. elminate possibilities.. take the most likely path. more info needed, and i bet you have more on hand than what is in the question.

Calcium is not available below 6.3 PH, canna flowers need an increase in PH every 2 weeks also. A flush with water (usually 7 PH) would fix this.. 20c if possible