There are so many varieties of poppy there are bound to be differences, but for most I don't think it matters very much, they are tough little things, but they need light to germinate. They say the poppy seeds in Flanders had lain dormant for years, but shelling on the battlefields brought them to the surface and exposed them to light. I suppose if you want poppies in a particular place it is different, but I just shake the ripe seed pods about, there are so many seeds some are bound to make it in the right sort of place, and if they are in completely the wrong place I just hoe them in. Maybe different too if you want something special like a Tibetan blue one.