Cut back warm-season grasses in fall or by mid to late spring. ... If you leave the trimming until spring try to make sure to cut them back to the ground (you can leave a couple of inches) by late spring, before new growth begins.

What happens if you don't Cut back ornamental grasses?

What Happens If You Don't Cut Back the Ornamental Grasses? As mentioned above, you will find that the green is starting to grow through the brown. One problem that will create is that the brown will start creating seeds. Once grass has created seeds, there is a very good chance that the grass will die out.

Do ornamental grasses need to be cut back every year?

When I cut too close to the crown, I usually lose a few clumps throughout the plant and need to pull out the rotten bits a couple of months into the season. Pruning should be done every year to give the new foliage a clean slate from which to shine.