Custom Palette Gradient

I have a custom palette for my column chart. I would like the column to be graident colour from itself to a lighter shade of itself.

For example my custom palette is "Blue", "Green" etc
I want to be able to gradient my columns so my question is.
In the Series -  Fill - Gradient I have my primary color as Automatic (based on my Custom Palette).
is there a way to set the Secondary Color to a lighter shade of the Primary color based on the Primary Colour value.

Thanks

Quentin