I went onto the PTR, with a pre-made level 90, and learned apprentice herbalism and mining, then went and found some nodes. The tooltip shows the nodes as orange and they can be mined by characters who have only just learned the profession, with a skill level of 1, as can be seen from the image after the break.
Much the same applies for Herbalism, where I was able to gather every herb I came across regardless of the tooltip colors. These stack in fragments too, called things like Torn Tea Leaf or Silkweed Stem, where again you can combine ten to create one of the full herb. Herbalism gathers also awarded Life Spirits and Water Spirits, just as you'd expect in Pandaria.
So, it's now possible to purely level mining and herbing in the new continent. It will be interesting to see what effect this has on the markets for gathered materials and whether it leads to a massive dip in price. It seems likely that it could, so bear that in mind when planning for patch 5.3.