they dont need to be warm like weed. Poppy seeds like it being cool. i just germed a load by chucking them inbetween some paper towells with water. no heat source just left them in a drawer. or chuck them directly into light soil. Nothing clay like.
Over here, (New Zealand) they're growing all over the place and it's cold as fuck. At our old flat they used to grow easily along with sun flowers etc;