Take a look at today's blog on color, value, and scale for some great tips on morphing the colors.
Are you planning to make the roses or just use some of the gorgeous fabrics out there with roses in them?
What type of pattern are you planning to use - there's another blog today about making the perfect 1/4" seam that has a great idea about bargello quilts and how to get around the matching up of seams. Personally, I wouldn't do that type of quilt as a beginner, but if you cut your materials into strips and make something like the zig zag quilt mentioned in the 1/4" blog, you could do multiple rows of the various blends of colors.
Good luck and let us know what you are doing!