I do not have 'Blue Light' but I have 'Crystal Fountain' they might look similar in photos but the flowers of 'Blue Light' are much bigger and less pinkish. 'Crystal Fountain' is not a vigorous grower for me.

Lauri,
I don't have any experience with Blue Light either, but I do grow Crystal Fountain. Mine is in full sun (in zone 4). It's a strong grower for me and blooms like crazy, but it never grows taller than 4 feet. I've had it for 8 years and it seems to get bushier and wider with each year, but was never interested in reaching the top of its trellis. ;) Something to consider when you pair it up. The color of my Crystal Fountain seems to be pinker than Blue Light, but I also found that it depends on the temperature. Some years it's more purple, other years its more pink. Hope this helps!

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Grow

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Thank you for the input buyorsell and grow-darnit! (Grow_darnit, your name makes me chuckle!âº). These are good pieces of info for me to consider and your pictures are lovely. Considering the pinkiness and not too vigorous height, Crystal Fountain sounds like she'll fit perfectly with Zephirine rose! :-)
Lauri

I don't grow either of these clematis, but I thought that I might suggest that you look at Edith Malek's website. She is a southern California clematis grower who helped to get out the message that clematis can grow in hotter climates than used to be thought. I was really encouraged to try more clematis in my climate because of her book "Simply Clematis".

In her book, she has a page for Blue Light, noting that it is a sport of Mrs. Cholmondeley. She also calls it "a beguiling clematis" and "an attention getter", and she says that it has "tremendous longevity as a cut flower". The listing in the book adds these characteristics:
it blooms early and then repeats
it grows up to six feet tall
it does equally well in sunny or shady conditions
it is colored a pastel lavender blue

She doesn't have a listing for Crystal Fountain in her book (published in 2004), but on her website, she has an article about sports, and she notes that Crystal Fountain is a sport of H.F. Young. She also has it pictured in the gallery section of her website.

Perhaps your library has a copy of "Simply Clematis" that you could borrow.

Here is a link that might be useful: Clematis Queen's website

My 'Crystal Fountain' is about 4' tall too but a lot wider and it is over five years old.

The spectacular 'Blue Light' that I have seen in person in a garden is in partial shade.

I live in zone 5, Crystal Fountain get 6 feet or more for me, it's in full sun until 2 P:M, blooms very well.