Ornamental Grass

A week’s worth of unseasonably warm weather has me thinking about one of my first garden chores of the season: trimming ornamental grasses.

So you trimmed yours back in the fall? This year, consider waiting until the spring. The dormant grass and seed heads (inflorescence) add a beautiful component to the frozen landscape.

Grass laying down with frost

After a winter’s worth of cold and wind, typically ornamental grass will begin to fall apart in early February. This is the cue that tells me it’s time to trim last year’s growth. Trimming ornamental grasses early prevents accidentally damaging  new growth that has grown into last year’s. Cutting into the tips of the new, emerging grass results in a ragged, torn look through the season.

If the ground has thawed enough to work, also consider dividing your grasses. Over time clumping grasses can become quite large, overwhelming walkways and adjacent plants.

Sometimes you’ll notice that the center will begin to die out. This is typical of many ornamental grasses, and another reason to revitalize the plant by division. If you decide to divide your grass, make sure to water the split sections, as they can dry out and die even when the weather is still cool.

If you’re tough, or just need to work out some frustration, you can use hand trimmers, but I’d recommend using a high quality electric trimmer like Stihl’s HSE 70.

STIHL HSE 70

First, make sure whatever tool you use is sharp. Dull trimmers can quickly become gummed up by the high levels of cellulose found in ornamental grasses.

This drift of grass in our yard has just started to fall apart.  The shorter clumps are Miscanthus strictus (Porcupine grass), and the taller grass in the center is the appropriately named Miscanthus giganteus.  Known also by it’s common name, Giant Chinese Silver grass, this clump reaches twelve feet by the end of the summer.  In addition to ornamental cultivation, Miscanthus giganteus is also grown for biofuel production.

Porcupine Grass

Begin by tying up the grass with garden twine. This will make it much easier to move, and a bit less of a moving target to clean up, should the wind begin to blow.

Tying up tall grass

Cutting tall grass at the bottom

The cut lengths of the Miscanthus giganteus are similar to bamboo and I use them much the same way, constructing tomato cages and using them as stakes around the garden.

Bamboo type grass

I find that moving the trimmed ornamental grass is much easier on a tarp than trying to stuff it into a garbage can.  We cut our grass into smaller pieces and compost it along with the rest of our garden clippings.

Dragging away grass on a tarp

  • Jo

    How short do you cut the grasses without damaging them?

    • Jason Doran

      Since most ornamental grass haven’t pushed up new growth yet, you can trim pretty close to the base of the clump. Later in the season you’ll begin to see what looks like sharp, tiny pinkie fingers- that’s the new growth you want to avoid trimming.

      You can also damage the new growth with a rake during spring cleanup (I write from experience!).