Sow them now, put them out where they can be weathered and forget about them for a couple of years.

Thank you Owd. In a pot? should the pot be buried or kept in a sheltered place? kind of compost would be best?

I have done mine in 9cm pots buried about half way down in multi purpose compost. Then place as Owd says.
in the first year you will get a root then the following year the shoot will emerge.

I also have some self sown in the garden and they do very well too.

Exactly as the lady says!

Thank you very much both. I'd better take the plunge - I've had them for about a month while I dithered.... I never expected that you could get self sown ones - they seem such an exotic plant!