The plant cultivar name is Maury, but it is also marketed in the US under the name Crater Lake. Choose the vendor wisely (brushwood is one of the good ones) because it is also on the plant list of some really awful mail order sources like Michigan Bulb.

It is a summer bloomer, type 3 prune, which IME are the easiest types to grow, though I have no experience with this particular plant.

There is info on the plant on Clematis on the Web. If you type just the name into the name blank on the search page for the site, linked below, it will give you info.

http://www.clematis.hull.ac.uk/new-clemlistsearch.cfm

Apologies for the slow response. This forum is so slow at this time of year that I only check it about once a week and due to issues the web site had with photo posting this summer, I think many people just stopped posting and checking at all.

Thanks so much saw it on “Clematis on the web” which was recommended on this site. The flower color and form sure ring my bell. I will search under the other names.

If you can't find it, 'Multi Blue' might be a reasonable substitution.

Wow Multi is a beauty love how it matures ... as I am new to clematis in my garden I thought it best to stick to the suggested group 3"s to start. I am just so pleased to learn I can grow them with success in Texas. Not sure where I have been these last 20++ years but missed that memo completely. I want to put them everywhere now.

What a beauty! Love it! Lisa

I bought a Mulit-Blue during Wayside’s sale last summer. Too early to say how it willl do, but it did grow ok. I wonder if it’ll be able to produce double blooms in our heat.

Maury/Crater Lake reminds me of a lighter shade of clematis Franziska Marie. No wonder I like it so much! I can’t find a closeup of Franziska Marie, but you get the idea here.

Ben, I grew Multi-blue in my former garden about a mile down the road. Multi-blue did great for me.(zone 10a). It bloomed double for me, and was lovely. Hope yours does well for you. Lisa