We bought a Vancouver Danielle Clematis (Monrovia) From a garden center because of the beautiful white flowers with purple center. The tag however shows a solid purple flower. When we asked about it the staff were stumped. They said they had wintered them over and thought they had been purple and that they definitely were supposed to be purple. They speculated that maybe they were not getting enough sun (but they looked to be in a sunny spot). What I am wondering is: is this likely to be due to genetics or an environmental change? Can we influence the color, or might it start producing purple flowers? Either color would be lovely, but I just really want to know why! :)

I found an article saying that there were 8 different hybrid Clematis in the Vancouver line created by Fred When, Sr.
Danielle is a cross between The President and Violet Charm and should have purple blooms.

http://www.clearviewhort.com/c...

I'm no expert buy yours looks more like Fragrant Star in the same hybrid line. There is an image on this link...http://vancouversun.com/news/staff-blogs/clematis-back-in-the-spotlight

I'm no clematis expert either, but it does look a lot like Fragrant Star. It's fairly common for nurseries to mix up tags.

You might want to test the soil. I don't know too much about Clematis, but when my Hydranga was blooming pink instead of blue, I added some Aluminum Sulfate to the soil and it changed back to blue. It might be at least worth it to investigate. But it's also possible that the person who labeled your plant forgot and left his/her brain on the kitchen counter when they left for work that day too!

Don't think clematis respond with flower color change due to the soil pH, sadly.

I'd recommend you go back when the clematis are blooming and buy one with purple flowers actually open on the plant, so you're sure what you're getting.