[Goldfinger]

I have a load of spring cabbage plants in desperate need of planting out, but with all this wet weather, I doubt I'll get them outside before they become (even more) pot bound, so was wondering...

Is it ok to grow them in the 'poly instead?

Do I need to do anything different with them being under cover?

[RichardA]

go for it, I grow spring cabbage regularly in GH and PT, watch for pests incl slugs and mice, water but not excessively as mildew can arise.
I have even planted in PT on occasions and then lifted some with a generous "rootball" and move them outside if in way of something else.
Best of luck
R

[Goldfinger]

Thanks Richard 

Am guessing to water from the bottom to stop any mould spots etc?...

[devongardener]

We grow spring cabbage in our tunnel every year.  Plant it now and it will be about 2-4 weeks earlier than outside.  If you sink a 1 litre pot beside each plant and then do your watering into that then you wont get mildew.