I love ornamental grasses because they come in a great variety, are easy to grow, drought tolerant and give 3 to 4 seasons of interest. By sometime in April you should have your ornamental grasses cut back. You can divide them too if you haven’t done so for a few years and if you have the energy. With some homeowners I have noticed a problem the past few years which falls under the are you “shear”-ious category when it crops up.
I have had samples of turf brought to me the past few years like the one pictured here:
When we have a mild fall and winter season here in Michigan we will get turf samples where Pennisetum ornamental grasses like Hameln or Moundry will seed in the turf. This causes panic for the home owner in spring as it begins to outgrow the desirable turf. Maintain your “composture” if this happens. Repeated mowings of the lawn will usually solve the problem as the ornamental grass will get exhausted and wear out as it is unaccustomed to repeated haircuts and a low profile. This is the best option because if you take the Roundup approach you will be doing some reseeding.
Remember this problem does not occur every year as we unfortunately do not have a mild fall and winter every year. I wish we did. If you have a lot of these ornamental grasses that adjoin a lawn area you might want to get “shear”-ious about cutting them back in late fall to limit seed distribution.