pruning ornamental grasses

Asked September 28, 2013, 3:39 PM EDT

How far back should one prune the grasses and when. I think I read 6 inches. The grasses here at Wind Crest were being cut back to about a foot. Many have dead stems and are left in place. Is it OK to pull them out? They look bad with all the dead brown stems in the middle of the grass as well as on the outside edges.

Douglas County Colorado

3 Responses

Thank you for contacting Ask an Expert. Ornamental grasses benefit from being cut back to a height of 2" to 6" just before new growth begins in the Spring. When the grass foliage is cut back/removed in the Spring, the regrowth begins earlier. When old growth is not removed in the Spring it can delay the new growth by up to three weeks. The dead stems left after cutting will help insulate the crown of the plant over the winter.

I'm confused (but that's not unusual for me!) The last sentence sounds like the grasses need to be cut in the fall. The second sentence tells me to cut them back in SPRING. Does that mean the stems cut in the spring protects them the following winter? I live here at Wind Crest in Highlands Ranch and there are hundreds ----- lots - didn't count them. I have pulled out some of the large dead centers, they look better but did I do it wrong?

Hi, this is Leslie, another DC Master Gardener. One reason to leave the cutting back of grasses to the spring is so they can be enjoyed for their winter interest. Cut back the faded stalks in March/April to 2-6". Spring is a good time to divide clump grasses, as well. Divide by cutting and saving vigorous divisions and discard the old center sections. Replant the new clumps and water well. Continue to provide ample moisture as needed until they show new growth.