Smooth Vertex Gradients

I'm looking at using a simple vertex color shader for a gradient background effect for my game. I tend to get to quite jarring color banding though.

Is there anything way of influencing how the fragment shader blends the vertex colors to possibly get smoother gradients?

Thanks.

 

I haven't seen any color banding with vertex colors (are you using mobile publishing with 16-bit color maybe?), but you don't actually need vertex colors anyway, you can just use a 2-pixel texture and bilinear filtering will take care of the gradient that way.

--Eric