Cornflower are Centaurea cyanus, and are annuals, so they will die after flowering, you can collect seed and sow them straight away, or leave them till next spring before sowing, if you do a few sowings next spring you can extend the flowering season, sow them where you want them to flower, Derek.

Thanks will do that because they really were very pretty when at their best .

I cut mine back down to ground level and they start growing again!! The new leaves are about 3" high at the moment