Caring for Ornamental Grasses in SeattleSeptember 23, 2009
Autumn is probably my favorite time of year to really enjoy & care for ornamental grasses. And, by grasses I don’t mean lawn. I do mean ornamental grasses and grass-like plants such as sedges and rushes. Plants like blood grass are brilliant red and showy at this time. Seed heads on Miscanthus are shining and flowing in the breeze (and frost). Little tufts on bunny grasses hop along at the edges of borders. And, hairy carex shimmers, promising interest into the winter ahead.
Well, it promises interest if cared for properly. Too often, all ornamental grasses are treated the same by unknowning humans with scissoring tools in hand. This can cause permanent damage. So to help you wade your way through your grasses, here are some general guidelines. Of course, in each genus there may be exceptions to the rule, but these tips should help you avoid the big mistakes.
- True Grasses:
True grasses have “elbows” or “joints” where the leaves run down the stems to the ground. They may be clumpers or spreaders, and they do well when cut down at the end of the season. What you define as “the end of the season” is your call. If you enjoy looking at seed heads swaying in the autumn sunlight, then you might wait until after a frost or until mid-winter to cut the plants down. If you are concerned about the plants spreading in the garden after forming and spreading their seed all winter, then you might cut them down earlier. Grasses like blood grass are easy to snip at individually to remove. Clumps of bunny grass are tight and with a sheet underneath are easy to shear and then pluck out brown old growth. Tall grasses like Miscanthus are best bundled tightly with string and then cut a few inches above the ground but below the tie. This way the bundle comes away in one bunch. Take care, these plants may have sharp edges.
- Sedges: Sedges have edges and no elbows. They are often mop-like and spreading. Generally, their seed heads aren’t showy.
They do not take kindly to being cut hard. Some will die back for winter. Most ornamental Carex, however, is an evergreen plant that should be combed and very lightly trimmed once or twice a year. I tend to comb mine out in mid-summer and again in fall or winter. After I comb out all the dead and stringy growth and remove any dead clumps, I then bundle the plant in my hands and trim off the dead ends, which should be around 2″ or so of the very tips. Its like giving the plant a little bob haircut. If the plant has been neglected for a long time, the center may be dieing out. In these cases, I dig out the plant to divide it and reinvigorate growth.
- Rushes: Honestly, I don’t do much with rushes. If they have dead growth, I remove those shoots to the ground. That’s about it.
This is basic primer barely skims the surface of ornamental grass care. There are many, many more grasses to choose from and care for. Some are weedier than others. Some are sharper and harder to care for than others. And, many are just plain wonderful and not to be missed for their fantastic, unique forms, textures and colors they add to to the garden. If you aren’t sure which kind of grass plant you have or if you have one that isn’t specifically mentioned here, get in touch for a coaching session for hands on plant care training and identification sessions. Or consider picking up a copy of one of my favorite grass books such as Grasses:Versatile Partners for Uncommon Garden Design or The Color Encyclopedia of Ornamental Grasses.
(This topic was originally published in October 2008 and updated in September 2009.)