Ornamental Grasses

by Sharon Stanford

Our garden contains about 40 varieties of Ornamental Grasses. Visitors often ask, when do you cut them back?   My standard answer is, it depends.

Grasses that are mostly evergreen, such as Festuca and Helictotrichon (Blue Oat Grass) should not be cut back.  Instead, comb through them to remove the grass blades that are dried.  This can be done at any time.  My favorite method is to use my hands and wear a pair of gloves with rubberized palms.  The dry blades stick to the gloves and come right out.  You may find that a small garden rake works better for you. Usually, last year’s bloom stalks will pull out in the raking process, but if not, use a hand pruner to clip them.

Grasses that take on a straw like appearance in the fall can be cut back at any time. In most years, we leave them standing and enjoy the winter interest that they provide. However, this year, we cut back several as soon as the December snow melted and left them flat and unattractive. Each year is different.

If you leave them standing, plan to cut them back prior to the start of new growth.  This will vary, depending on your location, but for me is around February 1 for cool season grasses like Calamagrostis (Korean Reed Grass – common varieties Overdam and Karl Forester) or Descampsia.  Warm season grasses like Miscanthus (Japanese Silver Grass), Molinia (Moor Grass), Panicum (Switch Grass), and Pennisetum (Fountain Grass) can be left a little longer, but I try to have them all cut back by March 1. 

Given the right tools, this need not be a difficult chore.  My husband Ed and I have discovered that this is a good team project.  I give the clump a farewell “hug”, while he (the master of power tools) uses a hedge trimmer to cut through the clump low to the ground.  Once it is cut through, I carry it from the garden.

If you don’t have someone to work with you, fasten a bungee cord or rope around the clump a foot or two higher than the point that you want to make the cut. This will hold the clump together and make it easy to clean-up.

Safety is key, particularly when using power tools. We purchased our hedge trimmer specifically for cutting grasses, so we chose a 30" bar to cut through the broadest clumps in our collection. Our model only trims in one direction. I require that Ed always trim AWAY from my legs.

What does the well-dressed grass shearer wear? I recommend covering as much of your body as possible to protect from small cuts from the grass blades. This isn't hard on a cold day, but on a warm day, I recommend an old long sleeve dress shirt with the collar turned up to protect your neck (see top photo for Ed in stylish grass cutting apparel).

- NPA members Sharon & Ed Stanford garden near Olympia, Washington. Their garden was recently featured in an article titled "Autumn Artistry" in Garden, Deck, and Landscaping Magazine from Better Homes and Gardens; has been featured in the Conifer Quarterly, the magazine of the American Conifer Society; and will be open to NPA members on Saturday, September 26, 2009 from 10 am - 4 pm, as part of the NPA Open Gardens program.

Touring NPA members’ gardens is the perfect way to learn about taking care of plants like Ornamental Grasses and solving gardening dilemmas.  If you have stories to share, we’d love to hear from you! Contact us at info@northwestperennialalliance.org.   If you’re not yet a member, joining NPA is the best way to learn about gardening through our Open Gardens program.  You could be touring fabulous gardens like this all spring and summer!  For membership information click here.