That looks like the kind of soil they use to grow trees in 5 gallon pots. That kind of stuff is no good for cannabis, especially young seedlings. If it looks like bark all the way through like it does on top, it is gonna kill those plants. I recommend transplanting them into an organic bagged potting mix that has peat moss and perlite as it's 2 main ingredients. People around here seem to love FoxFarm's Ocean Forest or Roots Organic, but I've used other brands with the same success.
They may call it weed, but you sure can't treat it like one.