Hi Axlera,

If it is Saccarum ravennae (it was Erianthus before the genus was reclassified!), the most often used common name in zone 5 and colder is "hardy pampas grass."

Whether or not you cut it down depends on if you like the look of it with the foliage from the previous year(s) combined with the new foliage, of if you want a "fresh new look" with all new foliage from the current year.

I love Saccarum so I got one for my backyard--knowing it was gonna be too big for my very small backyard--but I wanted it anyway! As I tried to pretend wouldn't happen, in a few years it was getting too big, I was constantly cutting off the ends of the grass blades so I could mow the lawn, and, knowing it was just gonna keep getting bigger I decided to dig it up and give it away!

Here's a pic the last year I had it for the full year. A little hard to see because it was behind a blackberry lily which has similar foliage!

Here are pics of it the day I "dug" it up! The hardest "digging" job I've ever done! It took me 3-4 hours, required a couple shovels, two crowbars, my hand-held sledge hammer, several little trowels, and a collection of the very sharpest knives I own! If you ever decide to dig yours up for any reason, I wish you luck! Sometime while I was digging it up I got two, very obvious, "insect" bites. Two weeks later I found out I had West Nile Virus!!! Ok! Not tryin' to blame that on the Saccarum, but it was Quite The Day!

Here are pics of The Digging, and what I'm really posting them for is to show you that this is how far I cut mine down every year, around now. If you wait too long there's more new growth that you'll be cutting off and it'll take a while for it to come back again. I recommend cutting ornamental grasses down as soon as you start seeing the very first of the new growth at the base. I'll also sometimes cut grasses down on a nice day in the middle of winter if they've been too knocked down by snow or winds to provide anything that could be considered Winter Interest anymore! I cut all mine down--just cut my Panicum/switchgrass down about a week ago--because I prefer the way they look with just the new growth each year. If you've been happy with the look with both the old and new growth you might want to just leave them alone. From what I've seen, most people cut them down. You can often find OGs along roads and in/around shopping centers (lots of them in the Thornton area), and if you watch, they're almost always cut down--right around now. Since you have two of them, depending on how close to each other they are, you might want to cut down one of them and leave the other so you can see it both ways to decide what you like best.

As with all gardening, there's no "right" answer! It's your garden/yard, so however you want it to look IS the Right Way!

Welcome to RMG,
Skybird

P.S. If you have time, go to the Who's Here in 2014 thread and introduce yourself to all of us! We're glad you found us!

Thanks for the warm detailed reply Skybird!
I'm on the fence about cutting them down, but we might start with one knowing they'll come back easily.

We have a corner lot and the previous owner elected to xeriscape with 2" crushed rock half way up the yard...guess they didn't like mowing! I spent a week filling pickup truck loads to remove the rock but ran out of steam once the front was clear...that was 12 years ago and the front yard is now an aspen forest.

Here's that hardy pampas grass we planted in the crushed rock garden...

I had a huge one in the front lawn at my previous residence. The landlord said he cut it back to about 4-6" ever winter, after it had turned brown and suggested I follow the same routine with it. I noticed the first time when I cut it, much of the inner growth was actually very much dead and starting to rot, so I pulled all that stuff out, too. It grew back like gangbusters. I think it's pretty common to cut them back. However, I planted some ornamental grass at my parents house many years ago and they have never cut them and they come back the same every year. I think they are a pampas grass of some kind, though, I couldn't be sure, they have never gotten much more then 4'. Though, I think I will trim them this weekend and see how they fare.

One last thing, when I cut back the pampas at our house before, it always gave me hives on my arms from all the hairs.