Yes, you should cut back ornamental grasses once a year if you grow warm-season types. Switchgrass, maiden grass, and little bluestem all go dormant in winter. They need last year's dead foliage removed so fresh spring growth can push through strong and healthy.
Pruning ornamental grasses the right way makes a big difference in how they bounce back each spring. I learned this from years of doing it wrong and then fixing my approach. With my small blue fescue clumps, I just grab the dead blades by hand and comb them out with my fingers in about two minutes per plant. My tall switchgrass is a different story. That job takes heavy-duty hedge trimmers and a good pair of gloves because the leaf edges can slice your skin open fast.
The reason annual cutbacks matter comes down to simple biology. Old dead foliage blocks sunlight from reaching the new growth buds sitting right at the crown of the plant. If those buds can't get light, your grass comes back thin and patchy instead of full and dense. Even worse, wet dead material packed against the crown traps moisture through spring rains. That trapped moisture creates the perfect conditions for crown rot, which can kill an entire clump you spent years growing.
Timing is everything with this job. The University of Missouri Extension says to cut back in late winter before new green shoots show up. For most gardeners, that means February through March based on your climate zone. Watch for the first tiny green tips poking up at the base. That's your signal to grab the trimmers. Cut too early in fall and you lose the winter interest from dried seed heads. Wait too long in spring and you'll chop off new growth along with the old.
Here's the height guide that took me several seasons to get right. Cut warm-season grasses down to 4 to 6 inches (10 to 15 centimeters) above the ground. This leaves enough stem to protect the crown from late cold snaps while clearing away the dead mass above. Cool-season grasses like blue fescue and tufted hair grass don't need a hard chop. Just run your fingers through the clump and pull out the dead blades, or give them a light trim to remove any brown tips.
The big exception to the annual cutback rule is evergreen grasses. Types like sedges, carex, and some fescue varieties keep green foliage through winter. They don't go dormant the way warm-season grasses do. Trimming decorative grasses in this group means pulling out brown or dead leaves by hand. Never shear an evergreen grass to the ground. That kind of hard cut will shock the plant and can set it back a full growing season or kill it.
I once skipped the annual cutback on my maiden grass to see what would happen. The results were ugly. New green blades tried to grow through the thick mat of dead foliage, came up bent and pale, and the whole clump looked like a tangled mess by June. I had to cut it back in the middle of summer, which stressed the plant badly. It took two full seasons to recover to its former glory. That taught me to never skip the yearly trim again.
One tip that saves me hours of cleanup each spring is tying the grass clump with baling twine before cutting. Wrap the twine around the whole bundle about halfway up and make your cut below the tie. The entire dead portion lifts away as one neat sheaf. No raking, no mess, and you can toss the whole bundle straight into your compost bin. Your grasses will reward you with their best growth yet once that old material is gone and sunlight hits those crowns again.
Read the full article: 10 Best Ornamental Grasses for Your Garden
