I researched flower meanings for a project, and was reading up on all of the meanings for different roses...
"By mixing rose blooms of different colors ... you can create a bouquet of emotions. For example, a bouquet of red and white roses would mean I love you intensely and my intentions are honorable. A random mix of roses would convey mixed feelings or send a message: 'I don't know what my feelings are yet but I sure do like you enough to send you roses.' " -the flower expert