Might try that next year, as I lost everything this year, swedes, various cabbages, cauliflower, kale all eaten to lace by the little fluttery bar stewards.Didn't bother with brassicas this spring, but set some seeds away in October after the bloody caterpillars had gone.
Germinated about 40 seedlings, potted them on, then planted in the unused greenhouse a couple of weeks ago....... doing well now, should have cabbage by Christmas, through to spring.
Still worth a go if you can germinate them inside first.