I need to make the transition smoother between the 2 different colored objects in my scene, somehow like one of the colors fades into the other one, while still keeping the line between them.
Create some materials- basic Orange and Pink materials (the ones you want to blend), Transition (this material'll be used for blending the ones above using material nodes) and Gradient (this'll be used to create a gradient texture for blending materials).
With Gradient material selected go to the Texture header, set the texture type to Blend, check the Ramp checkbox in Colors panel, then press the Linear and Vertical buttons in Blend panel. Also set the Mapping coordinates to UV. Your gradient texture is now ready.
Go to Node Editor and set up nodes as pictured below. First add two Material nodes- the Orange one and Pink one (Shift+A-->Input-->Material) and mix it using MixRGB node (Shift+A-->Color-->MixRGB). Use the Texture node (previously created Gradient texture) as a factor for blending. Plug in the UV output of the Geometry node (Shift+A-->Input-->Geometry) to the Vector input of the Texture node as shown below.