Established Pampas Grass
Plant in East Tennessee. No green on any of my pampas plants.
1) Are they dead?
2) Do I need to prune them down?
3) Must I always need to prune them down? (I love the plumes).
Winter was very hard in most parts of the country, and it may have damaged your plant. There's a possibility that you've lost it. Since no green is showing, go ahead and cut it back to the ground; you could give it some diluted fertilizer too. You should cut it back every year, which will promote more growth from the plumes. This article tells more: https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/growing-pampas-grass.htm