I believe they need to be stratified (fool the plant into thinking it is winter), then nick the seed coat and wait.
The easiest way is to winter-sow. The plant will self-seed quite successfully which is very much the same as winter-sowing.
I recently harvested some seeds if you need some; although they will flower more quickly if you can find someone with the little bulb thingies.
http://garden.org/ideas/view/g...
