Old World Flatsedge: A Hardy Sedge for Wet Areas
Looking for a tough, water-loving plant that can handle challenging wet conditions? Old World flatsedge (Cyperus cyperinus) might catch your eye. This sturdy perennial sedge has made itself at home in many tropical and subtropical regions, though it comes with some considerations for the environmentally conscious gardener.
What Exactly Is Old World Flatsedge?
Old World flatsedge is a grass-like perennial that belongs to the sedge family (Cyperaceae). Don’t let the name fool you – it’s not actually a grass, but rather a sedge, which you can identify by its characteristic triangular stems. Like other members of its family, it forms clumps and produces distinctive brown, papery seed heads that give it a somewhat rustic charm.
You might also see this plant listed under its synonym Mariscus cyperinus, so don’t be confused if you encounter both names in plant catalogs or botanical references.
Where Does It Come From?
Originally native to tropical and subtropical regions across Asia, Africa, and Australia, Old World flatsedge has traveled far from its ancestral homes. In the United States, you’ll find it established in Hawaii, as well as in the territories of Guam and Palau, where it reproduces on its own without human intervention.
The Non-Native Question
Here’s where things get interesting from a native gardening perspective. While Old World flatsedge isn’t classified as invasive or noxious in available databases, it is considered non-native in Hawaii and other Pacific locations where it’s currently established. This means it’s not originally from these areas, even though it’s part of the broader Pacific Basin flora.
If you’re committed to native-only gardening, you might want to explore indigenous sedge alternatives that provide similar benefits while supporting local ecosystems.
Growing Conditions and Care
Old World flatsedge is remarkably adaptable when it comes to moisture levels. It’s classified as facultative upland in Hawaii, which is a fancy way of saying it usually prefers drier ground but won’t throw a tantrum if its feet get wet occasionally.
Ideal Growing Conditions:
- USDA Hardiness Zones 9-11
- Moist to wet soils (though it tolerates some drying)
- Full sun to partial shade
- Can handle periodic flooding
- Tolerates a range of soil types
Garden Applications
This sedge shines in specific landscape situations where its water tolerance and low-maintenance nature are assets:
- Rain gardens: Handles both wet and dry periods like a champ
- Bog gardens: Perfect for consistently moist areas
- Erosion control: The root system helps stabilize soil
- Naturalized landscapes: Fits well in informal, low-maintenance designs
- Water features: Great around ponds or streams
What About Wildlife?
While specific wildlife benefits for this species aren’t well-documented, sedges in general provide habitat and nesting material for various birds and small mammals. However, native sedges typically offer more robust support for local wildlife communities, since native insects and animals have evolved alongside them.
The Bottom Line
Old World flatsedge is a hardy, low-maintenance option for gardeners dealing with challenging wet conditions. It’s not going to win any beauty contests, but it gets the job done reliably. Just remember that if supporting native ecosystems is a priority, you might want to research native sedge alternatives that could provide similar benefits while better supporting local wildlife.
If you do choose to grow it, you’ll find it’s pretty much a plant it and forget it situation once established – which can be either a blessing or a concern, depending on how you feel about plants that are really good at taking care of themselves!
