Pampas Grass Pruning, how late in spring?
Near my house I have a large patch of pampas grass, given to me by a neighbor in 1995, so yes, by this time it is a big patch. Over the years my mom and I both worked every spring to prune it down by hand. She has passed away, and I am in my 60s with arthritic hands and bad back. NO way will I try to prune this down again by myself. I have been able to get it down with the help of lawn mowing guys with power saws (Mom and I did it with elbow grease!) and very soon expect to get it down the same way. But in former times we did it in March before any green shoots appeared. Just in case the job doesn’t get done this year before it begins to sprout, is that OK or will it harm the plant’s progress later in the season? Right now it is a big brown eyesore in my front yard. The cleanup job is a royal pain you know where. But about August when the “brooms” are tall and swaying in the wind, it can be quite handsome, especially if it’s been a good year, not too much strange weather and bad storms.
The guy that I have hired to mow might have a Sawzall, as he is a professional. My clump is so large and thick (I would guess 10 ft circumference) that we were leaving parts of stalks a few inches high at the bottom. It’s a big ring now, rotted away at center, but interesting stuff grows down in there! Mostly giant weeds, but one year it was vegetables! Anyway, for the past 10 years or so, I have left brown stalks about knee high, my mother suggested that because it seems to help support the heavy growth, which often will fall down in storms.
You can cut down pampas literally anytime. Obviously you don't want to cut bloom stalks but it's OK if some green gets clipped. To preserve the arching, tall blades, have your clump cut before the end of April. Because you're unable to make a sharp, clean cut there may be ragged tips that turn tan/brown on new growth. You may want to recut those with sharp hedge shears for appearance's sake. If it is May before it gets cut down, it will still form seedheads but the overall appearance and size will be different. Do you have access to a sawzall? It has a better blade for this purpose than a chainsaw.