Do you mean the pointed shaped ones like Dutchman and Heart ?
I find they do best as an early summer crop. I will be sowing some seeds soon in the cold greenhouse. They get hardened off and planted under a net tunnel on the plot much like any other cabbage, with a handful or two of pelleted chicken manure in and around the planting holes. Then you just need to keep them watered if we have a dry spell.
I do another sowing of sweet tender cabbage a few weeks on for late summer and autumn, but I find the round headed ones do better for me and are a bit hardier so stand quite well at the end of the season.
