cabbage

i have a tray of hispi cabbage in cold poly tunnel.......they seem to be going a blue colour  will they be ok do you think  ty

yes  they have  now in 3in pots  ty

purple tinge on brassicas is sometimes the result of roots being dislodged (for example, wind rocking)  If you have repotted, it's possible the roots have either been damaged or still adjusting to the new potting media - just remember to firm the soil a little like you would when planting out and heeling them in.  It's not a long term problem and should be fine.