Wispy… billowy… airy…feathery… wavy…are some words we use to describe ornamental grasses. So often, though, they are stripped of all these adjectives.
When it comes to trimming, I find that grasses are one of the most mistreated plants, aside from trees. So many people don’t understand the fine art of trimming grasses. All too often they are just sheared up the sides and then across the top. Bim, bam, boom, done! Sometimes more care is given and they are then trimmed into little meatballs. Whichever shape you choose, the point is that grasses should not be trimmed into a shape.
Although, in our climate grasses go completely dormant much less than in colder climates, most do start pushing out new growth around this time of year. By trimming back the grasses we can easily freshen it up by removing any dead growth and we also have the opportunity to remove any weeds lurking beneath.
The ideal way to trim grasses is by gathering all the blades and holding them upright, much like gathering hair into a ponytail, then shearing them straight across. If it is a large species of grass, you can tie it up with a rope to hold in place before cutting below the rope. You can keep the rope on and compost them in bundles or you can remove the rope. I have also seen this done using a 2’ length bungee cord. The benefit of this is that it is easy to wrap around tightly and quickly hook in place.
To trim this Carex, gather all the foliage in your hand. Take advantage of this time to pull out all the dead foliage underneath, then cut straight across below your hand. 
After cutting, the trimmed foliage falls right back into place, hiding any dead foliage remaining and looking as pretty as ever.
It is quite efficient this way. By using this method, you are giving the grass a nice haircut. How high to trim depends on the grass and how much new growth is showing and how high that new growth is. It could be anywhere from a few inches to a foot.
One of my favorite grasses is Canyon Prince Wild Rye (Leymus condensatus ‘Canyon Prince’, Zones 7-10 ) This grass, like many others, has foliage that can be sharp and cutting.
Before tackling this grass, be prepared with long sleeves, long pants and good, tough gloves. It is not a bad idea to wear safety glasses as well to keep from getting poked in the eye. The Leymus has a tendency to lay down if it gets too much shade or water. Trimming it is a good way to help it keep its upright form and take the opportunity to pull away the dead growth that like to gather in the center.
If you are trimming back small grasses, like carexes, hand pruners do the job most effectively. For larger grasses, you can use hand pruners, shears or a battery operated trimmer.
Trimming time is also a good time to divide or transplant any new plants that have sprung up from rhizomes or seeds.
