Edgy Sedges for the Landscape

Carex<br> Edgy Sedges for the Landscape

Sometimes a landscaping solution for a troublesome area might be right underfoot. And sometimes, solutions require thinking outside of the traditional “landscape-design box.” Finding the right plant for partially shaded areas that do not require a lot of babying can often be challenging. That is where the world of sedges can come to the rescue.

By sedges, I am referring particularly to plants in the genus Carex. This genus contains thousands of members that are distributed worldwide. It is estimated that Carex contains close to 2,000 species, and about 500 of those are in North America. Chances are good that, unless you live in a desert, there are native Carex species in undisturbed places near your neighborhood, maybe even in your own yard. Many of the different native sedges look quite similar and often need to be distinguished from one another by examining maturing seeds under a microscope.

Sedges are in the Cyperaceae family. That name might remind you of cyperus, a plant mentioned in the Bible. We commonly refer to it as papyrus, which was used for ancient parchment. Also, let’s get something straight at the outset — I am not referring to nutsedge, often called nutgrass. This nuisance lawn weed is in the Cyperaceae family but in the genus Cyperus.

Members of the Carex clan look a lot like grass and are often mistaken for grass. Carex leaf blades can range from thin and bright green, to wide and blue-green, which might be mistaken for wild liriope or lilyturf (which is neither a sedge nor a lily, but rather a member of the asparagus family). Many of the more-popular Asian sedges have long, flowing variegated leaves.

The Cyperaceae family is characterized by their angular stems, which gives rise to the saying “sedges have edges.” The whole saying that helps to distinguish sedges from grasses from rushes is, “Sedges have edges, rushes are round, but grasses have nodes from their tips to the ground.” If you twirl the flowering stem of Carex in your fingers, you can feel its triangular shape. Twirl a grass or a rush stem, and you will easily feel its round shape.

Sedges can be found in many different kinds of soil, ranging from mucky and moist, to sandy and dry. Because of this adaptability, there is probably a sedge that would work where you live. Many of the popular ones being used in landscapes are well adapted to typical soil and moisture conditions, but to be sure it will thrive where you want to plant it, learn about whatever variety you might want to use.

Many of the sedges that are being used in commercial and private landscapes grow in partially shaded woodlands in their native habitat. Some tolerate more shade than others, and most will grow well with a lot of sunlight if not too stressed by drought. It is hard to generalize since there are so many; so, it pays to research what conditions are best for the varieties that interest you.

Whether growing native sedges or one of the popular introduced cultivars from other parts of the world, it is important to note that they are all cool-season growers. This means that they rest in the summer, resume growth in the fall and bloom in the spring.

There is a growing interest (pun intended) in using Carex in the landscape. Several native species are being used as groundcovers. They fit in well with a natural-looking landscape or with a mixed meadow featuring other perennials, places where low maintenance, water conservation and a less-than-tidy appearance are appreciated. It is also reported that several species of butterflies use Carex as host plants for their young.

Carex are also used in rain gardens and bioretention plantings. Some of the cultivars from Asia make great accents or can be used as border plantings. Australian and New Zealand varieties, many of which have foilage with a bronze tone, and the Asian variegated varieties are popular additions to container plantings.

If you are thinking about sedges for a groundcover application, keep in mind that although Carex can tolerate occasional foot traffic, they would not make a good lawn substitute where kids, dogs and sport activities regularly impact the area. Also, since Texas is such a large state with varying climates and soils, choices of Carex for a naturalistic meadow or groundcover application should ideally be of species known to grow in, or have a track record of thriving in, your region of the state.

When using sedges for groundcovers, remember that they are cool-season growers. Many can tolerate infrequent mowing to tidy up their appearance after a hard winter. But be sure to have your mower set to its highest level. It would be best to not mow them during the heat of the summer, when they go partially dormant. In my recently acquired, partially shaded woodlot, there are several native Carex species that have survived regular weekly mowing and no irrigation from the previous owner. I am now taking a no-mow (or infrequent-mowing) approach and letting them naturally reseed; so hopefully they will eventually shade out competing annual weeds.

Let’s take a quick look at some of the ones you might run across in your local garden center, botanical garden-plant sales or online sources.

A popular and readily available group of Carex are those in the EverColor series. Bred from the Japanese species C. oshimensis, they all have variegated foliage and grow in attractive mounds. Some cultivars you might see include the eye-popping ‘Everillo’ with long, flowing bright golden-yellow-to-chartreuse foliage which acts like a bright spotlight in a partly shaded landscape. There are several green-and-white cultivars in this series, including ‘Everest’, ‘Everglow’ (C. morrowii), ‘Eversheen’, plus a few others. Their colors are brightest when grown with some morning sun.

A new hybrid that is showing up on nursery shelves is Carex ‘Feather Falls’. Its narrow, variegated foliage makes a large mounding clump about two-feet tall and five-feet wide. It looks similar to some of the C. oshimensis cultivars but is a hybrid that includes some more sun-tolerant species.

Another Japanese Carex is C. morrowii, with variegated cultivars like ‘Ice Dance’ and ‘Silk Tassel’. I particularly like the Japanese sedge Carex phyllocephala ‘Sparkler’, which grows unlike most other sedges. Its green-and-white variegated leaves whorl around and up the upright stems to about 15 inches. In a few years, it will form a colony through spreading rhizomes.

One sedge that is not bright green or variegated like so many others is C. buchananii ‘Red Rooster’ from New Zealand. Its foliage is bronzy brown, and to some it looks like it is dead, even though it is actually quite alive. I have seen it effectively used in a mixed container planting, which I think may be its best use. Another New Zealander is C. testacea ‘Prairie Fire’, which is recommended for container and mass plantings in sun. Its bronze-and-green foliage, tipped in orange, can take more sun than many other sedges.

Chinese pink-fairy sedge (C. scaposa) is unlike any other sedge, with its highly visible spikes of pink flowers. Native to Southern China and Vietnam, this wide-leaved evergreen is listed as hardy in Zones 6b to 9b. I haven’t grown it, but it is on my wish list!

Native Sedges

As mentioned earlier, the best choice for native sedges would be ones that are known to grow in your part of Texas, whether ones that occur naturally or others that have been successfully used in landscapes in your region.

A couple of species that are used in naturalistic plantings that are native in Tyler, where I live, are Texas sedge (C. texensis) and Leavenworth’s sedge (C. leavenworthii). These both look similar, with the difference being some fine details in the inflorescence. Both are recommended and used as lawn substitutes for areas with infrequent traffic. They have fine-textured foliage and low overall height (about 12 inches).

Both of these species grow in clumps and spread by reseeding, so eventually they will nicely fill in an area. They can tolerate infrequent mowing (best on the highest cut-setting and not in the summer), and once established require no additional irrigation. They grow naturally in well-drained soils but are adapted to a variety of soil types and moisture levels.

Texas sedge is mainly found in East Texas from the Red River all the way to the Gulf Coast. Leavenworth’s sedge has a greater distribution in Texas and occurs from North-Central Texas to the Coast, and east to the Louisiana border.

A similar-looking sedge that I saw listed by an online nursery is sweeping sedge (C. bromoides). Unlike Texas and Leavenworth’s sedges, which grow in a range of moisture levels, this one does best in moist soils and might be a good candidate for a rain garden.

A popular Texas native sedge for accents and borders is the Cherokee sedge (C. cherokeensis), which grows in clumps about two-feet tall and wide. In the spring, it produces attractive seed heads that look like little narrow flags hanging among the wispy foliage.

There are a couple of popular sedges with wider blue-green foliage that grow only to about 12 inches tall. These include C. laxiculmis ‘Hobb’ (also sold as “Bunny Blue”) and C. flaccosperma, which I have seen also listed as “Bunny Blue.” As I mentioned earlier, taxonomy of sedges can be confusing, and identities get adjusted after more examination. I have not grown either of these cultivars, but I do have a blue-green foliaged Carex on my property that I suspect is C. flaccosperma, and I am encouraging it to grow. C. laxiculmis is listed as being adapted to USDA Cold Hardiness Zone 9 and colder, and even though it is apparently not native to Texas, it should adapt here. C. flaccosperma is native to the eastern third of Texas from the Oklahoma border down to the Gulf of Mexico.

One sedge you might run across while searching for sedges for groundcovers is Berkeley sedge (Carex divulsa). I have seen it also referred to as grassland sedge and meadow sedge. It is not a North American native, but rather it is from Eurasia and has naturalized in many parts of the U.S. and Canada. Tolerant of heat and humidity, this clumper grows equally well in dry, sunny locations as in moist shade.

As I mentioned, there are hundreds of Carex species native to all parts of the United States, with many native to Texas. As interest in naturalistic landscaping increases, more species are being used and trialed for use in various conditions, including boggy soils, raingardens, drier uplands, as well for drought-tolerant groundcovers. What I have given you is just a small sampling of some of the ones you might encounter if you go hunting for sedges as you seek to make your landscape more sustainable with these tough and attractive plants. tg

By Keith Hansen
Smith County Horticulturist, Emeritus
Texas A&M AgriLife Extension Service