Hi Scottish are you asking about the big multi petalled ones or the small alpine one? If the later it shouldn't need protection from frost.

I planted the big, blousey, multi-petalled one, whose bulb looks like a mini jelly fish, last autumn. Planted 250 of each colour and they started coming up about 4 weeks ago. I think they're along the same lines as the larger De Caen Anemones where you can really plant them at any time of year and get flowers all year round. Hope so anyway !!!

If in doubt, plant after frost. They will bloom just a little later. In any case there should be some info on the bag they came in or those little patches which you must scan your I-phone (if you have one- I do not) on to get any information at all.

Thanks folks.
MG They are the big multi petaled jobs. I only discovered today (after researching the others) that there was smaller alpine ones.
Badfish - yes, those are the ones. I've read autumn or spring planting but can't find any info on hardiness. All I can find is they don't like being waterlogged.
Loosestrife - the packaging isn't very clear apart from as I've said above plenty other info apart from frost protection.
I've found a contact us on the breeder's site, so will drop them a line and see what they say. I'll put any reply here for future reference (if I receive one that is!)

Hi Scottish, there are about 400 species of Ranunculus, most of which are completely hardy, R Asiatica is half hardy, and R Lyallii is borderline completely hardy, Derek.

Thanks Derek - the ones I fancy are Ranunculus Cafe Caramel but nothing on the packet to give species type.

Hi Scottish, unfortunately 'café caramel' is a variety of R Asiaticus, just about the only 1 that isn't completely hardy, I think they deliberately don't put the species on the packet, hoping that people will automatically assume that they're hardy, and then buy more, thinking they have done something wrong, and it must be their fault, when actually it's the supplier that's at fault, for not giving the right information, Derek

Checked mine today and i have 7 different colours of asiaticus, all planted in November, all up and looking damn good despite temps going down to -6

Thanks Derek, I think you are right re not enough information. You may remember on many occasions I have passed comments re plant labeling, especially for growers up here. Thanks for taking the time to look up the information for me, it's much appreciated.
Badfish, great that yours have survived temps down to -6, we've been experiencing similar temps here recently too.
Here's the reply I received from the breeders yesterday - it might be useful to someone in the future. I had informed them that I intended to grow them in pots, so their reply reflect this:

"Ranunculus are hardy down to minus 3/4C so I would suggest that newly potted bulbs are best in the cold frame while they are getting established especially with the cold spell we are experiencing. One also has to remember that bulbs in pots are more vulnerable to frost damage because the frost will come in from the side as well as the top. For frost to get down even 2 inches in the border it has to be fairly prolonged and severe. This may well be the case where you live in Scotland but very often of course a long hard frost is preceded by snow which is like a blanket. The other important thing to remember with Ranunculus is that they do like to be well drained."