Cabomba, also known as Carolina fanwort, green cabomba, or Brazilian fanwort, is perennial aquatic plant that grows fully submerged with the exception of the flowers (and occasional leaves) of mature individuals, which float atop the water.
It’s considered native to portions of South America, including southern Brazil, Paraguay, Uruguay, and northeast Argentina, as well as the southeastern US. Some sources list it as native to the west coast, but this is contradicted by the fact that it’s an established invasive species throughout California, Washington, and parts of Oregon. It’s spread throughout the US due to its popularity in aquaculture.
Species in the genus Cabomba are well known for their thin, fan-shaped leaves, and has earned this genus the common name of the fanworts. Believe it or not, Cabomba used to be listed as part of the water lily family (Nymphaceae). However, it’s now placed within the family Cabombaceae (which was previously considered a subfamily of Nymphaceae until 2016 with the emergence of improved phylogenetic technology, techniques, and understanding). Some sources still place the two together. Cabombaceae contains two genera – Cabomba, containing four species, and Brasenia, containing two species.
Facts, Benefits & Uses of Cabomba
Regardless of the exact species, all members of Cabomba are naturally subtropical plants, and their branching, fan-like leaves make them excellent oxygenators while also providing protective spawning habitat for fish and aquatic invertebrates. Carolina fanwort is no exception to this. In addition, Cabomba species have a few unique adaptations to help them survive and reproduce. Not only do they have attractive white, yellow, or sometimes purple flowers, but they also have nectar glands at the base of each petal. This means that pollinators are rewarded with not only pollen, but also nectar, making this an exceptionally valuable plant to bees, butterflies, moths, and other prospective pollinators.
Interestingly, the flowers of Cabomba species close and pull underwater at night, presumably as a means of conserving energy when pollinators are not active. Furthermore, three out of the four Cabomba species (including Carolina fanwort) possess trichomes. These serve as a defensive structures, excreting mucous that coat the plant and protect it from predators like insects. The trichomes themselves as well as the mucous also help to protect the plant from being overly disturbed by currents, though these plants do prefer still or very slow-moving waters.
When water levels are low, Cabomba is able to drop its lower leaves to conserve energy. Some of these newfound nodes can instead become roots if necessary, to better anchor the plant and access more nutrients in times of drought.
Cabomba Growth, Hardiness & Climate
Cabomba is a hearty plant, and a very quick grower – in the right conditions (ample sunlight, pH ideally between 6 and 8, temperature between 72 – 82° F (22 – 28° C), Carolina fanwort can grow as much as 2 inches in a single day! It can grow in water as deep as 10 meters, and has been known to reach nearly 7 feet in height (though closer to two or three feet is more common, and it prefers water 5 meters in depth or less).
In late summer and into fall, green cabomba will begin to toughen and branches will start breaking off. These then float to different areas, which help facilitate the plant’s spread as these sit dormant (so long as the water doesn’t freeze) and take root as new plants the following year. Subtropical climates suit the best, but they do just fine in hardiness zones 6 and up, so long as they have access to at least partial sunlight. Blooming typically occurs from May through September, though may start sooner and end later depending on the location and climate.
How to Plant Cabomba In Ponds
Cabomba is most easily grown from cuttings. These can initially be found in store and planted in an inch of substrate or anchored to the bottom with a weight. Once established, however, you can have more cabomba by simply trimming the tops of existing plants and then anchoring these cuttings in your pond. They should establish roots within a few weeks. Cabomba can also be allowed to simply float in the water, but floating individuals don’t tend to be as successful as rooted ones.
If you’re planting cabomba that already has roots, be gently as their roots are thin and delicate. Before planting, swish the plant around gently in a container of clean water to help remove any potential pests as well as loose leaves that would otherwise float about your pond or tank. Place the roots in approximately an inch of mud topped with substrate to help hold the plant in place, deep enough that the plant will be fully submerged (at least a foot deep, ideally, to allow for continued growth). Since it’s capable of growing quite tall, you may consider placing cabomba in areas where they won’t overshadow other small plants or hide your fish too much if you wish to see them.
How to Care For Cabomba (Fanwort)
Carolina fanwort is a relatively easy plant to grow. In the right conditions (appropriate lighting levels, pH, and temperature as discussed above), these plants can really take off and create a dense, forest-like look in your pond. This means that they are likely to need to be trimmed, maybe as often as every few weeks. In some cases, the plant can spread out of control via its own dropped foliage and seeds, so you may need to remove some individuals to prevent overcrowding.
To mitigate this, you can plant cabomba in areas that are partially shaded or waters that are a bit on the cooler side. This will slow their growth, and deter overcrowding. This may be a slippery slope, though, as too much shade can cause the plants to go dormant or simply die.
If you opt to trim the plants as needed, you can replant the cuttings (this will, of course, add to the population, which may be beneficial at first but a possible nuisance later), or dispose of the cuttings. When disposing of them, don’t simply throw them aside, as they may be able to establish themselves in nearby natural waterways and cause potential ecological upset. Instead, throw them away or compost them. The same goes for any naturally dropped foliage – dispose of them in the trash or compost where they can’t spread, and don’t leave them in the pond where when decaying they may degrade water quality.
How to Winter Cabomba (Fanwort)
Cabomba does not need to be brought to an indoor aquarium for winter. Most individuals are capable of going dormant for several months through winter, unless the water freezes entirely, and then coming back up the following spring. A top layer of ice won’t harm them, as cabomba has been found thriving in Canada and Michigan, outside of its native range, in lakes that get quite cold and freeze over in the winter. In particular, broken fragments lie dormant on lake and pond bottoms, becoming green once the water thaws and putting out roots.
The only step that you need to take is cutting the cabomba down as low as you can before winter and removing the trimmed portions from the water. Otherwise, dead and dying cabomba, particularly when large, release a great amount of manganese and deplete oxygen levels if allowed to die and decompose in the water.
Is Cabomba Toxic, Poisonous or Invasive?
A native of southeastern South America and the west and east coasts of the United States, Carolina fanwort is considered invasive in the central and midwestern US, Australia, Canada, Asia, and much of Europe (including the UK). Do take care to check if the plant is native in your area, or legal to own, before purchasing. In non-native areas, green cabomba is harmful in that it forms dense mats, decreases oxygen levels, alters pH levels, outcompetes native plants, and clogs waterways so that animals and watercraft cannot get through.
The methods of introduction into these areas is thought to be due to naïve aquarists disposing of plant bits and entire aquarium tanks via dumping outdoors, intentional cultivation in these areas in natural lakes, ponds, and rivers, by ignorant but often well-meaning individuals, etc. It can also be spread to a lesser extent by birds and aquatic animals, such as muskrats and turtles, as they pass through and bits of the plant break off and stick to them.
Its popularity as an oxygenating aquarium and pond plant have led to its distribution to consumers worldwide. As state above, please dispose of this plant properly (directly in the trash or compost) and if you live outside of its native range, absolutely do not plant it in a naturally occurring waterway or in a garden pond that is fed by a natural waterway, as the seeds and dropped branches will travel.
Cabomba caroliniana is not toxic to humans or animals, and in fact provides a valuable food source and habitat for aquatic invertebrates, which in turn are fed on by fish, turtles, and waterfowl. Some fish and waterfowl may directly feed on the tender leaves.
Is Cabomba Edible? Will Fish Eat it?
Cabomba is indeed edible. It doesn’t seem to be overly coveted by pond fish (goldfish generally don’t touch it), but some koi and, interestingly, Siamese algae eaters, have been known to occasionally munch on the plant. This shouldn’t harm it, though, particularly since cabomba is such a prolific grower.
Where to Buy Cabomba & Seeds? (UK & US)
As a popular garden plant, Carolina fanwort can be found readily in most aquarium and pond retail stores, as well as online nurseries. It tends to sell out fast, so you may have the best luck ordering online, or requesting that a shop order it in for you.
