What I would do and have with lots of different types of fruit and veg is plant the whole peat pot/paper pot in the permanent spot or you run the chance of losing roots and run the chance of killing the weed. @daz49 maybe able to help.
I hope you mixed that Supper thrive with the gal of water. Next water add some hydrogen peroxide this will help your roots
Keep us posted on how there doing,
I’ve had similar root loss and never lost a plant. For future reference, you can plant peat pot and all. Just make sure the top is below the soil. You can tear the top down sone and/or slash a few holes in the pot.