Happy ornamental grasses need to be divided every three to four years. Smaller species (those less than 2 feet wide or so) are easy to cut in half with a sharp shovel or to dig up and gently pull apart with the help of a soil knife. Bigger grasses can prove more of a challenge. The important thing is to do something about the overgrown grass as soon as you notice a possible problem. Don’t walk away and think, “I’ll do it next year”; doing so only makes rectifying the issue that much harder. I like to divide grasses in spring just as I start to see the new growth starting. This is easier to do because there isn’t a lot of tall (and often sharp) foliage to fight through. Actively growing grasses will keep growing after division. In fall/winter most grasses are dormant, and they can struggle to recover. I have two methods everyone can use for dividing behemoth grasses.

See more:

The Best Ornamental Grasses for Every Season

Get Four-Season Interest Using Ornamental Grasses in the Landscape

Let’s Argue About Plants Podcast Episode 147: Great Native Grasses

Method 1:

Carefully take a sharp shovel or pitchfork around the outside edge of the grass. Go into the main part and cut out a portion about the size of a 1-gallon container. Get as much of the root ball out as possible so you can transplant the sections. Continue cutting out chunks around the edge, eventually leaving just one good portion in the center, which will happily regrow in the same spot (just starting off as a much smaller plant).

Method 2:

The second method is a little more involved and should be used when the grass is so overgrown that the center is dead. In this case you need to dig up the entire grass, getting as much of the root ball out as you can. At this point I use a small chain saw with a “dirty” chain to cut the root ball in half (pictured) and then into smaller sections. The chain I use is just for cutting things with dirt on them. I also use it for large roots or timbers full of soil that need to be cut. Cut sections off and replant (much like the first method), but throw away the dead section in the center.

Susan Calhoun is the owner and principal designer of Plantswoman Design in Bainbridge, Washington. She is also a FineGardening.com regional reporter for the Pacific Northwest.

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