This review is simply a warning to people who are colorblind: Don't bother, find a different game.
From the Microsoft store - "Plant beautiful flowerz, set up matches and cascades, and keep planning ahead to make your garden flourish round after round. Make your matches at a leisurely pace or strategize your placements for higher scores. Includes the Standard and Expert version of Flowerz. Based on the popular MSN game, Carbonated Games brings you Flowerz for Windows Phone..."
This is true, and as others have said, the challenge kicks in with multicolored flowers, where after once the primary color is cleared, the flower turns into the secondary color. What makes this game difficult for the colorblind is that at level 10 standard mode, there are 3 flowers that look identical, but aren't. I have been told that the flowers are light pink, light blue, and white, but they are indistinguishable to me.
I'm basically guessing for the light colored flowers on level 10+. I feel like I can somewhat tell the difference due to the shading at the edges of the flowers, but I'm often wrong, and I can't make it to level 19 or a 9k score.
If you can't see the differences in the image above, do NOT play this game. In my opinion, this is poor design, and it's completely unnecessary to have colors this similar.