I have several different grasses, some tall, some short. I have always thought one needs to cut these back rather drastically in the early spring, which I have usually done. Sometimes this works well (Karl Foerster), other times not so well (orange sedge). I totally dislike the look of a newly shorn grass, so likely put off the haircut too long. Sometimes I've had grasses just kind of die out following their annual haircut (which they may have done anyway). I've tried experimenting with cutting and not cutting on the same grass, and am getting a better feel for those who really don't need to be sheared back. Looking for feedback on which grasses you cut, when you cut, and which ones you might just leave alone. Here's what I have:

Karl Foerster feather reed grass -- I let this stand all winter and cut it back to new growth when it wakes up in spring. This seems to work well. The main problem I have with Karl is differentiating between his new growth and quack grass that insists on sharing his space..

Sedges (carex) - I think I've found that giving these a haircut when they are laden with seedheads works to both perk them up and prevent rampant reseeding. Usually mid-summer (?) and I just cut off the outer edges that are laying on the ground. The rest then springs up nicely. The ones I have sheared hard seem to take a long time to recover (and there's that icky look).

Mexican feather grass - I've tried letting this go and also cutting it back, not sure which I prefer. It seemed to take forever to recover from a short haircut, maybe it just needs a trim? This does reseed for me, but I'm OK with either pulling them or transplanting the babies. Seems to take the new seedlings a few seasons to really get in their stride.

Switch grass (panicum) - new last fall. I let it stand over winter then cut back to 4" or so. Not sure how this will do, it is in an outlying area that gets little attention.

Fountain grass (pennisetum) - if these overwinter for me I cut them back to the ground. Some are more tender and I guess out of my zone, I've lost several. In containers on my back deck (full sun).

Miscanthus - I don't think I currently have any of these, but have in the past. I do like them, not sure what they need to stay healthy.

Thanks for your input, always so great to find out what works (or doesn't) for others.

I cut my Hakonechloa Aureola back very short in October. If I let it go too long the individual pieces come flying out with the first strong wind and I hate running around trying to get them all. I also cut back my carex (Siderosticha). Both bounce back beautifully.

Here is some good info---http://www.bluestem.ca/april-03.htm#cutting

I cut most of my grasses back hard in the early spring.
All of these:
Pennisetums (except Little Bunny and those like that because I have NEVER been able to get them to over winter).
Panicums
Eragrostis Purple Love Grass
Muhlenbergia Pink Muhly Grass(some years it does not over winter, I'm just on the cusp of its survival zone)
Calamagrostis (Karl and Overdam)
Korean Feather Reed Grass

I have Carex Evergold for the first time. I looks a little ratty but not too bad. I'm not going to cut it back. Maybe just trim out some bad spots

But I have Carex Frosted Curls and I give that monster a hair cut late summer and hard cut in early spring.

I have Juncus. I'm not sure if that is really a grass. I have the corkscrew version. I do NOT cut that back. Just a bit of trimming. But if I had the regular straight variety I think I would cut that back partially in spring (I cleaned my neighbors beds and she had some, I cut it back )

I no longer have any Miscanthus. They were thugs in my gardens. But I did cut them back hard when I had them.

All deciduous grasses can be cut back in fall or spring. I prefer spring since the dead foliage holds a little structure during winter and also protects the crows that bit more. Also when the regrowth start you don't end up with a messy tangle of new, green and dead, brown stuff; it's odd looking.

Evergreen grasses can just be 'combed' out with your hands.

I have some miscanthus giganteus planted along one side of the driveway to provide some privacy from a neighbor. Cutting it back each Spring is a big job. One of the few things I wear gloves for. Have really sliced up my arms doing it.