Hi Pippi
I grew this for the first time this year (planted last fall), and it came back this year nicely. I planted mine next to an Oriental poppy too, and they looked so pretty together! I had the same flopping problem though. I read somewhere that you should cut the flower stems all the way back after they are done blooming, and you may get another bloom. I planted mine in the fall, so this is really the first year for me, and I know nothing else about it, like where to collect the seeds from. And, since I've already cut all of the stems down to the ground, I won't have a chance to find out! They were in the way and had to go. I'm pretty sure that you leave the foliage though. Mine still looks good even without flowers, so it can stay as long as it keeps looking good!