Moved them up to 1 litre pots which had the bottom half filled with foxfarms happy frog, I topped up the upper half with more pro-mix.
Also added dynomyco to the roots when I transplanted, i think it took a couple days for it to really kick in but I'm getting pretty good growth especially considering they're still under the blurple (another week or 2 before they go under the marshydro)