[A. Fallowfield]

I have two trays of igloo caulis in my polytunnel that don't seem to be doing well. I planted green trev at the same time, and they're ready to plant out!
They're very small (they are a small cauli) and the tips of some of the leaves have gone brown. The ones in the foreground are easiest to see. As you can see, they are still upright and are growing slowly! Anyone any ideas?