Trimming ornamental grasses

Asked January 27, 2020, 11:56 AM EST

I have heard that it's important to trim back ornamental grasses to a couple of inches in late January/early February. I am curious as to whether this is necessary. Does it improve the plant's health or appearance? I have many of these on my property, and if it isn't significantly beneficial, I'd just as soon not bother. Thanks.

Baltimore County Maryland

3 Responses

Many ornamental grasses used in landscapes in our area are warm-season grasses, meaning that they sprout once the soil has warmed and their growth occurs in warm weather (as opposed to spring or fall, like our cool-season Fescue turfgrass). Keeping the old growth on the plant is thought to help protect the crown in winter; seedheads of native species will be of benefit to overwintering birds. If an extra-tall grass that may lodge (get pushed-over) in winter from snow or ice, you could do a partial cut-back any time to reduce its bulk.

Cutting warm-season grasses back is best done at the end of winter or any time in early or mid-spring prior to emergence of the new grass blades. Cutting the grass back too short could damage these growth points, so be sure to leave a few inches of "stubble" to avoid this. In the wild, grasses would be grazed down by wild animals or have their old foliage burn off in wildfires; our yearly trimmings are a substitute for this to keep the grasses attractive. Old growth left on may look a bit unkempt but will not hurt the plant. Sometimes, as they dry and wither, much of the old foliage blows away by the end of winter on its own.


Thank you! That's a big help.
(Also it's the answer I wanted to hear...)