I planted these, probably, end of October last year. Tough buggers. Took them several weeks to germinate but once they had they kept growing throughout the winter, and really took off in Spring. Their time has come though, and I chopped them down with the sickle this morning, composted the upper parts, (the leaves are rich in nitrogen, apparently). I can turn over the whole bed now. I've kept a few WFB stragglers by the path, see how they go to seed.