Cabbage question...

[pjb]

I've found an un-opened packet of cabbage seeds lurking amongst all the other packets I seem to amass, they are "Mammoth red rock", can anyone tell me if they are suitable for sowing any time soon or are they a spring sowing only type? There's no info on the packet and I couldn't find much on Google, anybody? Thanks.

[pjb]

[ceres]

and I couldn't find much on Google, anybody?

Really?  Got lots of hits from different suppliers.  All give latest sowing as May/June, days to maturity 90-100.  But if you've got the space, what have you got to lose but a few seeds?