http://apps.rhs.org.uk/rhsplantfinder/pfregions.asp?ID=109542

The RHS Plantfinder lists a number of stockists. Copy and paste the link I've given you.

We grow loads at the nursery for spring time. Very popular, but not many suppliers. But thats for 100 plug plants, so RHS will have more of an idea. I dont think that they are 100% hardy, i think the cold and wet kills or damages them,

thanks for the replys