Fiber optic plant, also known as slender club rush, low bulrush, or slender bulrush, is a native of southern Europe, the Mediterranean, and portions of Australasia. It can also be found in coastal parts of Africa, South America, and the west coast of North America.
Though also sometimes called fiber optic grass or cotton bud grass, this interesting plant is a sedge (more specifically, a bulrush), not a grass, belonging to the sedge family Cyperaceae and the bulrush genus Scirpus. Formerly, its scientific name was Isolepis cernua. Among gardeners and plant nurseries, it is also known by the names livewire grass, fairy lights, and, amusingly, Tina Turner grass.
This plant’s name is a result of its appearance when flowering. During the summer months, pale brown to white small, fluffy flowers strikingly contrast the bright green, slender, grass-like leaves. Particularly in sunny lighting, this gives the plant the appearance of fiber optic lights, particularly if there’s a breeze that results in the flowers swaying in and out of the leaves, resembling blinking, shifting lights.
Facts, Benefits & Uses of Fiber Optic Plant
Often chosen for garden ponds for its unusual appearance, fiber optic plant grows best in damp or wet locations. In its natural range, it can often be found on sandy banks, in peat-rich wetlands, along pond and lake edges, and along sandy, peaty coastal wetlands. Like other members of Scirpus, fiber optic plant is excellent at stabilizing soils and controlling erosion, soaking up excess nutrients and pollutants from the water and soil, and they provide habitat for a variety of wildlife, such as small passerine birds and waterfowl. If allowed to grow partially in the water, the drooping leaves can also provide refuge for fish and frogs.
Additionally, a study focused on natural methods of remediating a polluted wetland found that bulrushes are able to break down and effectively remove close to 40% more diesel fuel from the wetland than the control environment that didn’t have bulrushes present. If planted directly in water, fiber optic plant can also aid in oxygenation.
Fiber Optic Plant Growth, Hardiness & Climate
Fiber optic plant is not one that will quickly overtake your garden, having a rather slow growth rate. In ideal conditions in which it is able to grow year-round (ample sunlight, temperatures that don’t drop below 20 degrees Fahrenheit (-6.6 degrees Celsius), and plenty of moisture), fiber optic plant can grow up to a foot tall with its leaves spreading to reach a similar diameter. In less-than-ideal conditions, it can range between 10 to 30.5 cm in height (4 to 12 inches), the latter of which likely taking several years to accomplish.
Blooming typically occurs from May through September but can occur earlier or later depending on the location and season’s conditions. In colder regions where significant freezing occurs (below hardiness zone 8), fiber optic plant typically becomes an annual plant unless transferred indoors for winter. Higher hardiness zones (8 through 11) will yield an evergreen perennial plant capable of living many, many years.
How to Plant Fiber Optic Plant In Ponds
Fiber optic plant can be grown directly from seed by gently pressing the seeds into damp soil that has consistent access to moisture but isn’t saturated. However, it’s often easier to propagate this plant from cuttings of already matured plants. A hardy plant, cutting off parts of the plant and replanting them should result in fairly quick rooting, and this plant will also readily self-seed. Alternatively, many plant nurseries carry this novelty plant.
Seeds and established plants should be planted in Spring after the threat of frost has passed. If you wish to plant from seed but want them ready to bloom in the summer, you can plant your seeds indoors in pots with peat-rich, damp substrate and then transplant any successful plants in the spring. Seeds should not be fully covered with soil, as they need ample sun to germinate, so consider placing the pot in a well-lit windowsill or sunroom protected from the cold and elements.
If planting an already-established fiber optic plant around a wetland or garden pond, take into consideration its original growing conditions. If it was previously exposed to standing water, then you should be able to transplant this same plant or cuttings from it to marginal areas without issue. If, however, it was grown simply in damp soil but you wish to plant it marginally in water, you will need to gradually expose the plant to more water for several weeks so the roots can adapt without rotting. Start off with just a centimeter or two of standing water, then gradually double this each week. Fiber optic plant isn’t overly picky and generally loves water, so don’t worry too much if you don’t get the timing or amounts perfect. Just so long as it’s gradually introduced to more moisture, it’ll very likely re-establish just fine.
How to Care For Fiber Optic Plant
Fiber optic plant is wonderfully low maintenance. So long as it has continual access to moisture and full or at least partial sun, your fiber optic plant is likely to thrive. It can be grown in full shade, but this most often results in lankier leaves with no or stunted flowers, which rather diminishes the fiber optic effect of this plant. To help mimic natural growing conditions, you can add some peat pellets of peat humus to your soil; this will help retain moisture, as well as increase acidity moderately. This isn’t necessary, however, as fiber optic plant can also be found in sandy, more alkaline conditions, as well. In the autumn, placing peat humous or mulch around them will help them to survive colder temperatures, so long as they don’t consistently drop below 20° F (-6.6° C).
Fiber optic plant doesn’t spread quickly and is easy to control if it does begin to pop up beyond where you’d like it to grow. Simply dig up and divide the plant as desired. During the growing season, you can trim several inches off of lankier plants if desired. This will not harm them, and will stimulate new, bright growth while preventing overgrowth. Don’t trim them during winter while the plant is dormant.
How to Winter Fiber Optic Plant
Fiber optic plant is relatively hardy, meaning its flowers and leaves cannot tolerate significant cold or frost, but it can survive winters if they’re not overly harsh (below 20° F). If you live below USDA hardiness zone 8, consider bringing S. cernuus indoors for the winter and keeping it in a well-watered plant in a bright, sunny window or insulated patio. This isn’t necessary, however; as mentioned previously, fiber optic plant self-seeds readily, so you’re likely to find new plants come Spring even if you live in a region with winters that regularly fall below freezing.
Is Fiber Optic Plant Toxic, Poisonous or Invasive?
Though any plant grown outside of its native range (mentioned in the introduction) has the potential to become invasive, fiber optic plant is not listed as an invasive species even outside of its native ranges. This is because it’s a slow-growing plant that doesn’t readily overtake areas. Nonetheless, we always encourage readers to only utilize plants that are native to their area. If you live outside of the fiber optic plant’s native ranges, consider either growing it indoors, or obtaining similar sedge or bulrush species that are native to your area.
If you’re in the United States, this native plant finder can help you with that task: https://www.nwf.org/nativeplantfinder/. Alternatively, a quick online search of a plant’s Latin name can tell you where it’s considered native and invasive. We also include guides like this one for many other sedge and bulrush species in our plant guide section.
Unfortunately, all parts of fiber optic plant are toxic if ingested to animals, dogs, cats, and horses alike. Though no known research exists on the topic, it’s reasonable to assume that this plant would be toxic to fish if they ingest it, as well. Young shoots typically result in the greatest reactions, as the toxins are more concentrated during this time. We’re unsure of what exactly causes the toxicity, but it can also cause mild skin irritation, so it’s best to wear gloves when handling.
Is Fiber Optic Plant Edible? Will Fish Eat it?
Fiber optic plant is not edible, and in fact is moderately toxic. Consuming the plant can result in nausea, vomiting, loss of appetite, headache, and other flu-like symptoms. If you have fish, consider not planting S. cernuus directly in your pond, as leaves may trail into the water, and it may also drop seeds in the autumn. As always, be sure to clean any dropped foliage from your pond to help maintain water quality and fish health.
Where to Buy Fiber Optic Plants & Seeds? (UK & US)
Mature fiber optic plants can be found at a variety of local, in-person nurseries throughout its native range (though it seems to be most easily found in-person in the Americas and Europe), as well as via online plant outlets. You may also find seeds and cuttings online and in local nurseries.
