KC Gardens

Groom your ornamental grasses in time for their spring debut

Ornamental grasses are hardy and low-maintenance.
Ornamental grasses are hardy and low-maintenance.

Ornamental grasses have long been a staple in the Kansas City landscape. They are prized for their tolerance to our local conditions and provide interest in the landscape. And although they are low-maintenance, there are a few chores that should be undertaken to keep them looking good year-round.

Cut back old growth

Ornamental grasses are rejuvenated each year by removing the old brown growth. Cutting back is best done late winter through early spring, before the new growth starts to emerge from the base. Removing the old growth is a no-brainer, but tackling the project is a challenge.

Old stems are fibrous. Their edges can be sharp and leave battle wounds. Work gloves and long sleeves are highly recommended.

The best way to start is by corralling old growth. Wrap the stems with duct tape, twine or a handy bungee cord. Wrapping keeps the debris together, making cleanup a breeze. The bundle is tied up, ready for removal.

The best approach to cutting back is what I call the warrior method. This is not for small hand tools but rather larger hand or power tools. Electric hedge clippers are my go-to method; I let the motor do the work. A pruning saw can also be handy but requires more effort.

Once the proper tool is ready to go, cut the grasses back as low as possible to the ground. This removes all the dead, brown growth, letting the fresh green shoots emerge for another year of beauty.

Divide to stay ahead

While caring for ornamental grasses is easy, dividing the overgrown clumps is anything but. If left to grow, these plants can quickly spread to several feet or more. Large clumps can look unkempt and overgrown, losing their beauty.

Overgrown clumps are difficult to get out of the ground to divide. Jokingly, it takes a jack hammer. Many gardeners have broken shovel handles trying to pry the extensive roots out of the ground. In my own garden, I have taken an ax and power tools to a mature clump to divide.

Our extension master gardeners have adopted this guideline when working with ornamental grasses in our demonstration gardens: We divide when the clump reaches 12 to 18 inches in diameter. This means a clump is usually divided about every three years. At this size, a sharp shooter spade can get around and under the root ball so that the plant can be lifted with less work.

Avoid replanting large divisions. The larger the replanting, the sooner the need to divide it again. A nice size clump is about 4 to 6 inches in diameter.

It should go without saying, but these plants don’t need fertilizing and, once established, rarely need watering either. Too much good care means it’s time to divide again.

Dennis Patton is a horticulture agent with Kansas State University Research and Extension. Got a question for him or other university extension experts? Email them to garden.help@jocogov.org or visit KCGardens.KansasCity.com.