Calea zacatechichi seeds

My friend gave me some Calea zacatechichi seeds. I've looked for some suggested methods of germination, but so far all I have found is that it's hard to germinate. And suggestions would be greatly appreciated. Thanks in advance.

They are hard to germinate. I got some seeds (they might have been not fresh) sowed them 6 weeks ago and just 1 germinated yesterday. They need light to germinate, so don't cover the seeds.
Since I had hardly germination, I also started them in vermiculite 10 days ago, but still waiting for germination for those.
I think (but I'm not sure) they need a lot of time to germinate. I keep them on a warm place, since I'm in zone 6.
Will keep you updated if there is any progress.
Still have some seeds left, so if you're succesful some way, please let me know.

Jonna

Olá Amigos!
Consegui algumas sementes de Calea, estou tentando germinar, mas, na minha região Sul do Brasil é muito difícil pois o inverno é rigoroso. Coloquei elas sobre o substrato de terra e vermiculita e estou aguardando, já passou 2 semanas e nada ainda.
Consegui muda de um tipo de Calea não amarga, chamada Calea zacatechichi var. Macrophylla. Vocês conhecem essa variedade?
Mando uma foto anexa.
Desculpem os erros, estou usando o Google tradutor, pois, conheço pouco do seu idioma.

Grande abraço para vocês e bons cultivos!!!