when the Allium has finished flowering, cover the seed head with a paper bag and tie lightly to secure. leave until the seeds are dry (you'll know when they are dry by giving the bag a quick shake!), then cut the top of the flower off, then turn cut head upside down so the seeds are captured in the bag. Then keep in a dry place until you want to plant them. The actual Allium plant should come back year after year.the Allium can be put into plant pots first if wished but I have always planted my dried seeds straight into the ground and they have always flourished.