ok, first off your growing medium is pretty much soilless, it has no nutrients, so you'll have to give it everything it needs to survive, all the NPK, and micro and macro nutrients. Your flush removed anything that might have been residing in the peat. The only thing retaining water and nutrients is the peat, so your pots are going to dry out quickly. I don't think you are rootbound like the guy above me thinks considering the size of the plants vs the amount of medium you have. Yes its been 5 weeks, but the plants haven't been given enough nutrients to grow properly.
You are going to be battling keeping nutrients available for your roots to obsorb, while at the same time not rotting them by keeping them wet. You pretty much have a mixture that would be better suited in a netpot over a DWC bucket.
I would take a sheet of plastic and lay it out on the floor, put the stem between your fingers with your palm towards the soil and gently lift it out on its side, you will probably have alot of medium fall apart on to the plastic which is fine, you can reuse it, set what you have for a root system off to the side and cover it with something dark so you are not exposing the roots to light, and do the same to the other plant(I'd throw the dieing one away...its not worth saving at this point)...
Next take more peat OR some type of potting soil and mix that about 50/50 with what fell off your root system to create more of a medium to hold nutrients. If you go with potting soil it has nutrients, including the macro and micro nutrients you need as most specific fertilizers dont have any. If you go with pete you'll need to purchase some other type of fertilizer that contains those(like calcium, magnesium, iron, manganese, etc)...put this mixture back in your pots leaving a little left on the side, put a hole large enough to set your root ball back in and repot it.
I have a feeling you still have room in the size pots you are using to develop the root system further. IF when you pull this mess out the roots are holding on to the entire grow medium structure, then upgrade to a larger pot, and give it a medium you can easier maintain at this point until your thumb gets a little greener
Hopefully that helps a bit...good luck!