Burn or deficiency? Or something else?

Time to think about getting them out of those solo cups.

 

Lets try 'Root Bound" the lack of nutes(yellow leaves) shows that
pot them up

good luck

 

I dont think that's light burn; looks more like iron deficiency, brought about by an imbalance...

 

put them in their final pots and use some decent soil is my advice take it easy on the nutes though

 

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I too was thinking a Mineral Deficiency

 

Just saying ....... Compost = nutrients .............never becoming dirt/soil nor minerals except sodium mainly.
This is why we have salts in the oceans.
Dirt/soil= minerals

 

I screwed up It's dirt/soil = Minerals