Q.Is there anything I can feed Pink Pampas Grass to get more reddish plumes?
Eight plants are in a line spaced about 4′ apart and the flowerbed is rich with chicken manure compost and sphagnum moss which normally grows ANYTHING.
You will not be able to change your pink pampas grass to a red color.
You may see different shades of the original pink plant color, depending on light and growing conditions.
Here is a link about Pampas grass.