What's Wrong with My Pampas Grass?

Q. My question is about our pampas grass which is now about six or seven years old. In the beginning the plumes were white, but now are brownish yellow. In fact, they look dirty. I notice too most of the plumes are coming on only half of the plant. 

Pampas grass flowering

A. Pampas grass is native to the grasslands and plains of South America. It has evolved with fire which is a clue about how to manage it. In the wild, range fires every few years keep these things burned to the ground and renewed naturally.

            By the way, the standard size pampas grass is very large and should not be used in landscapes that do not have the room to support its growth. There are dwarf forms of this plant that would be more suitable and in a variety of colors.

They are a pain in the neck to prune and some people burn them to the ground every three or four years where burning is permitted. If burning is not permitted, they may be cut to the ground and hauled off. This avoids the problems surrounding fire. Burning or pruning helps renew the plant and keeps its growth more evenly balanced. 

When pampas grass first blooms, the plumes may be an assortment of colors depending on the type of pampas grass. After a short time the flowers may begin to turn an off shade of the same color.

Pampas grass continually puts on new growth from short rhizomes on the periphery of the plant. As it does this, the center may stop being very productive. In some cases parts of the plant may die as they get older, larger and overgrown. 

Giving the plant adequate water, fertilizer in early spring and pruning it properly should help quite a bit in maintaining good growth and color.