What was in the soil besides Promix before you got it? I don't think Promix has much in it to begin with, so if you've only given them that and a bit of 4-4-4, they may very well be deficient in nutrients...the 4-4-4 is gonna take a few weeks to start working, though.
And no need to mix the 4-4-4 in water, it's more effective if you scratch/mix it into the top couple inches of soil. And while you're at it, you could also add some compost or worm castings. When I top-dress dry ferts, I usually mix them with a few handfuls of worm castings, then mix that into the top layer of soil, and water it in.
And if you're worried about them getting too big, just take clones and in a few weeks you will have smaller, more manageable plants to work with.
Good luck!
