What is the downside of cutting pampas in August?

Question

I have 2 major stands, one is doing great but full of old dead growth; the other seems to be “disappearing”…any help would be greatly appreciated! I love these plants but obviously haven’t shown them enough love!

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Answer 1

I can't see any problem with cutting it back now except that you won't have any nice plumes for winter interest. Pampas grass is a warm-season grass so it has already passed its growth spurt. Once the leaves start browning it is OK to cut them back. Many cut ornamental grasses back in fall to keep the garden tidy. Others like the winter interest so wait till just before new growth begins.
https://www.gardeningknowhow.com/ornamental/foliage/pampas-grass/pruning-pampas-grass.htm