Ornamental grasses are one of the first plants to greet us come spring. You’ll see little green shoots coming up from the cut-off crowns and know that spring is finally really here. Decorative grasses can be warm season, cool season, or evergreen grasses. Warm season and cool season grasses are sometimes called “deciduous grasses”, meaning that the foliage of these types of grasses turn brown in the fall but tend to remain standing. These grasses when left as they are can provide winter interest to a landscape, particularly when they are in the background.
While you can leave these grasses without care all year, they will tend to look more attractive if you cut back ornamental grasses in the forefront either in late fall or early spring.
Cutting these grasses may seem like a difficult task, especially the kind with razor-edged leaves, but it doesn’t have to be. To cut back the grass, first, take twine or string and wrap it around the grass creating a sheaf. This will be easier to manage and cut through. Then, take your hedge shears—or for an easier job, a hedge trimmer or power hedger—and cut the grass about 4–6 inches above the crown of the plant. You want to protect the crown because it helps to insulate the roots through the winter, so don’t cut the grass at ground level.
Once you’ve cut your grass plants down you’ll want to take the dead material and place it on the compost pile. Dead grass is a great way to get nitrogen into the soil, so it’ll help your compost pile do its job. If you happen to have a shredder you can also run the grass through it and make a great mulch for your other plants!
Remember, ornamental grasses grow not only tall but wide as well. Eventually, in addition to cutting them down, you may also need to split them so they stay manageable in your landscape layout. We’ll cover how to split grasses in a future post! In the meantime, find that string and get going on your trimming!
Early spring, before the warm season really starts, is a good time to do a special kind of herbicide application known as a pre-emergent herbicide. Pre-emergent herbicide applications help to eliminate weeds before they can grow. Some of the common summer grassy weeds that this treatment can prevent are crabgrass, foxtail, goosegrass, and sandbur.
Once the soil temperature rises it will be the perfect time to apply a weed preventer. The correct temperature means that it should be 55 or above for at least 2 days. Usually, this is at some point between March and April.
For most granules or liquids are the two main methods used to apply pre and post-emergent herbicides. It is vital that the active ingredient reaches into the soil, so if you are using granules you’ll need to water them in. If you’re using a liquid, it will seep in on its own.
It is important to make sure you’re applying pre-emergents before the growing season because once weeds—such as crabgrass, or broadleaf weeds like dandelions, clover, ragweed, and carpetweed—are visible it’s too late and you’ll have to use different treatments such as a post-emergent herbicide weed killer. When using a post-emergent weed killer be careful during application because lawns and decorative plants can be burned or killed by these chemicals.
Apply pre-emergent herbicides in both late summer to early fall as well as early spring because this is when most weeds bloom. These pesticides have an active ingredient which does not stop weed seeds from germinating, but instead keep them from sprouting. This means that the application is best done just when the seeds germinate. This usually happens twice a year. For the fall application wait until temperatures drop to the mid-70’s for three to five days in a row. For some weeds, such as annual bluegrass, multiple applications over consecutive years may be necessary to achieve the level of control you’re looking for.
Pre-emergent herbicide applications will not last through consecutive seasons so it is necessary to apply them each year, twice a year, to get the weed control you want for your lawn.