I've never found these easy plants to grow but every year I buy one more just to try to keep them going! I've got three or four all looking healthy right now, and all planted directly into a south facing bed with pretty poor soil. They are shaded by tulips until late May, and then by the 'Bowl of Beauty' paeonies so they don't get too much full sun. In the past I have planted them in shade but they've not survived the very harsh winters. Growing them from seed is something I have never managed to achieve so I've given up buying expensive seeds. My dream of a huge drift of these lovely plants is just that, I'm afraid, a dream.
I have hundreds of the blowsy bright scarlet double oriental poppies, which I can't eradicate ( even if I wanted to! ) which grow and proliferate like weeds! Peaty soil, lots of rain, cold winters, late frosts ( Aberdeenshire ). And of course the bright lemon Welsh poppy just about everywhere.
Like Yvieh I have never managed to grow ANY variety of poppies from seed, so I would tend to agree that it's more a question of luck! Keep trying with the meconopsis, Rosemary, and maybe try buying different varieties as some may be tougher than others ( I buy whatever happens to be in the garden centre and my three are all blue, but slightly different shades ). They're worth it.