When And How To Prune Ornamental Grass Plants
Pruning of ornamental grasses is simple and straightforward. So simple that this may be one of the shortest "How To" articles I've ever written and published. The instructions below apply primarily to the ornamental grasses of which the foliage dies during the winter.

Pruning Instructions

When to Prune
Regarding most ornamental grasses, the foliage should be left standing throughout the winter for visual interest. That being said, substantial clumps of certain types of annual grasses tend to flop (or totally collapse when subjected to heavy winter snows). So, if you live in an area that is known to receive heavy snow you can cut foliage halfway back before snow arrives. Otherwise, wait to prune until late winter or very early spring, before or just when you see new growth begin to emerge. That being said, I usually prune grasses back before seeing any new growth because I don't want to tip the new blades when pruning. 

If you wait too long, and new foliage has already emerged, go ahead and trim the plant back. It's better to do that than to look at dormant, straw-color foliage mixed with fresh green growth throughout the season.

How To Prune

Before pruning your ornamental grass it can make the job a lot easier if you tie the grass up with a string or rope. Simply gather up all the dead blades and tie a string around it. Then proceed with pruning

To prune your dormant ornamental grass, use hedge trimmers or clippers or a sharp pair of bypass hand pruners, such as pictured right, to trim foliage to just above the ground. I usually prune back to about 3 to 6 inches above ground. That's about it!