Hornwort Care Guide – Planting, Growing, and Propagation

Today, we will be talking about yet another fascinating aquatic plant, which is popular for its use in aquascaping and planted tanks in general. The common Hornwort (Ceratophyllum demersum) has a very unique appearance (horn-like needles) and it adds great value to any kind of tank set-up.

The role of Hornwort plants in an aquarium is numerous: they beautify and decorate the tank, help in oxygenation, provide cover for small fish species and inverts, clean the water, etc.

If you are a beginner in the aquarium hobby, looking to get an undemanding plant, which will grow and survive against all odds, then the Hornwort is one of the best options. This is a very resilient plant, it can adapt to new conditions and survive in your learning curve. In addition, it costs less yet adds a lot of value to your aquarium.

Keep reading to know more about the Hornwort, we will provide you with a detailed care guide about this versatile plant.

Hornwort – check out the price on Amazon

Quick Notes about Hornwort

Common Name	Hornwort
Other Names	Foxtail
Scientific Name	Ceratophyllum demersum
Tank Size (minimum)	15 gallons (~60 liters)
Difficulty	Easy
Lighting	Medium
Optimal pH	6.0 – 8.0
Water hardness	Very soft – very hard
Temperature	68 to 79 (20 – 27C)
Substrate	Not needed
Growth Rate	Moderate to high
Placement in Tank	Background / Floating
Height	Up to 1 – 2 m (3 – 6 ft)
Fertilizer	Not needed – Low
CO2	Not needed – Low
Propagation	Sideshoots and Cutting

Its name “Ceratophyllum demersum” emanates from the Greek words ‘Keras’ (Horn), ‘phylon’ (leaf), and the Latin word ‘Demerses’ which means – Underwater.

Origin of Hornwort

Ceratophyllum demersum (common Hornwort) is native to North America and over time it has spread to all other continents of the world (Africa, Asia, Australia, Europe, and South America) with the exception of Antarctica.

Hornwort is a cosmopolitan submerged plant found in freshwaters in most parts of the world. This is a completely submersed plant and is commonly seen in ponds, lakes, ditches, and quiet streams with moderate to high nutrient levels.

This plant belongs to the Ceratophyllaceae family and is scientifically classified as follows:

Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Order: Ceratophyllales
Family: Ceratophyllaceae
Genus: Ceratophyllum
Species: Ceratophyllum demersum

Habitat/Ecology of Hornwort

Hornwort can be found inhabiting slow-moving water- streams, marshes, ditches, lakes, ponds, and other wetlands/humid areas. They can be seen growing on tree trunks /bark of trees in tropical rainforests.

Hornwort is a perennial plant and can thrive for a long period of time if living conditions are favorable. It is hardy and tolerant towards a wide range of water conditions, which makes it capable of surviving in diverse kinds of habitats.

This plant has been declared an invasive species in recent times because it can spread and disperse easily thereby wreaking havoc on environments. For example, in New Zealand, Hornwort has out-competed native plants and is known to cause disruption to Hydroelectric power plants.

Description of Hornwort

Hornwort has some peculiar features which make it unique and easily distinguishable from other aquatic species.

It is a green to yellowish plant, which bears needle-like filamentous leaves which grow on its tall, slender stems. This plant has no true roots, its base leaves with root-like structure, and the rhizoids help in anchoring it down.

The Hornwort has been observed and known to grow very tall. In nature, it can grow up to 1 – 3 meters (40 – 120 inches!) with a diameter of about 2mm. If adequate care is not taken, this plant can grow out of the tank and completely overrun it.

The leaves are small and produced in whorls of six and up to a dozen. As a flowering plant, Hornwort bears flowers (both male and female) in one plant. The flowers are tiny and inconspicuous, 2mm (0,08 inches), and possess brown petals. These flowers give rise to an ovoid fruit, 4mm (0,16 inches) in size.

In the wild, during the autumn season, Hornwort develops buds, which sink to the bottom of the water that develops into new plants during Spring. Hornwort grows completely submerged but it can be floated on the water’s surface as well.

Tank Requirements/ Water Parameters

The most important thing is to ensure that the Hornwort is provided with a suitable and comfortable tank set-up and that proper water parameters are maintained to support healthy growth and development.

Tank size:

I have to start off by saying that Hornwort is not a good option for nano tanks. The recommended minimum tank size for growing this plant is 15 gallons (60 liters). A larger tank is better in this case as the plant is known to grow at a fast rate and can get out of control if not properly taken care of. In addition, a smaller tank will create a situation whereby the plant will outgrow the tank and can “choke” other aquatic species in the tank.

Water type, Temperature, Hardness, and pH:

Water Temperature: Due to the hardiness and durable nature of this plant, it can survive in a wide range of temperature conditions. However, water temperature is one of the most important factors for growth. Hornwort can grow 1 – 2 cm (0.4 – 0.8 inches) a day.

To ensure the best growth of this species, the temperature should stay in the range of about 64 – 86 °F (18 – 30 F) with around 75 to 79 (24 – 27C) being optimal. You can always check this at regular intervals using a thermometer.

pH: Optimal pH should be between 6.0 – 8.0. You should test this with a pH testing kit at least once every week.
Note: According to the study, in nature, Hornwort can tolerate huge pH fluctuations (from 6.5 to 10.2 with high values in spring and summer).

Hardness: Hornwort can thrive in soft to hard water. It simply does not care. However, for optimal growth, you should maintain water hardness in the range of 3-17 dGH.

Lighting:

Under proper lighting conditions, the Hornwort grows at a visibly fast rate. This plant species thrives best under medium lighting, avoid too weak or strong lighting. LED lighting is your best bet for this purpose, the lighting duration should be about 10 – 12 hours per day.

Related article:

Advanced Guide to Planted Tank Lighting.

Substrate:

Hornwort does not need any substrate. Even more, it can be a real problem to keep it in the substrate, especially if the plant has not developed its “anchors” yet. Do not try to shove the stems into the sand or soil. This part will simply rot away.

However, you can weigh it down with something else or use suction cups for that.

Related article:

How to Anchor Aquarium Plants? Pros and Cons of Different Methods

Supplements:

Hornwort grows at an incredibly fast rate, because of this behavior the plant takes up a high amount of nutrients from the tank water and it will tend to diminish the tank’s supply of nutrients. Therefore, it is recommended that you add fertilizers every week to make up for the lost nutrients been used up by the plants.

Note: Hornwort appreciates Nitrogen and Iron-based fertilizers more for optimal growth and development. The addition of CO2 is not compulsory but it will help the Hornwort and other plants positively, don’t overdo it anyway.

Important: If you keep shrimp in the tank, I would highly recommend reading my articles:
CO2 in a Planted Tank Guide
CO2 in a Shrimp Tank
How Copper Affects Dwarf Shrimp
Shrimp Safe Plant Fertilizers
The point is that a high level of CO2 and Copper (most fertilizers contain copper) is extremely dangerous to the shrimp. In addition, Hornwort is also sensitive to copper. In my article about copper, I also refer to the most popular shrimp-safe plant fertilizers.

Planting Hornwort

Hornwort is a versatile plant, it can be planted on the water surface (free-floating) or ‘rooted’. Although Hornwort does not produce roots, when growing near the bottom, it will form modified leaves, which it uses to anchor to the sediment. Sometimes this plant forms dense mats just below the surface.

As I have already mentioned, DO NOT try to root Hornwort in the substrate. It will not end well. The buried part will start decaying and, in the best-case scenario, you will get bare strings with bushy tops. Hornwort simply does much better floating in large bunches and in aquariums.

Floating Hornwort is easy, just place it on the water column and give it some time to stay put and grow. You can also use suction cups to hold it firmly on the tank walls.

Also, before cultivating the Hornwort you should put the fish species present in the tank into consideration.

Propagation of Hornwort

The propagative means of the Hornwort is by vegetative fragmentation, this is a common method for invasive plant species. In this process, a part of the parent plant is separated from the plant and it grows into a new independent plant. Also, the main stem grows multiple side shoots or buds that may detach, and plunge into the tank water and growth continues.

However, if you want to propagate Hornwort in the aquarium – cut off the stems and let them float on the water surface. Stems from regular trimmings can be used for this purpose. After some time, these stems will grow and develop into a new plant.

Note: It really does not matter where you cut it. You can cut it into 2 or 3 parts and Hornwort will still survive.

Maintenance & Care of Hornwort

Hornwort tends to grow like crazy, you will need to trim this plant regularly to avoid it from spreading everywhere and overstuffing the tank.

Trim the overgrown plant stems with a pair of trimming scissors and dispose of the trimmings in the bin or keep them for replanting.

Once again, Hornwort appreciates fertilizer application because it absorbs a lot of nutrients from the water as a result of its fast-growth nature. Therefore, a liquid fertilizer application is recommended to make up for the huge nutrient requirements of the plant.

Endeavor to keep the plant away from the filter to prevent the dropped leaves (needles) from getting stuck in it. Also, collect dropped needles during regular water changes and dispose of them properly, leaving them inside the tank will disrupt the water chemistry and can breed harmful organisms in the tank.

Look out for signs of nutritional deficiencies in the plants and address them accordingly.

Benefits of Hornwort

Aquascape: Well, certainly it is not possible to use Hornwort in Iwagumi aquascape. However, this beautiful plant with nice needle-like leaves can be an excellent decorative addition for jungle aquascape.

Removal of excess nutrients: Hornwort has heavy metal absorption properties. It is helpful in absorbing harmful chemicals that are emitted from fish waste, decayed plant matter, and tap water such as nitrates, CO2, ammonia, and phosphates.

Clears the water: If you have cloudy water, Hornwort will make it crystal clear!

Outcompetes algae: Its leaves help to prevent the growth of certain types of algae e.g. blue-green algae. Hornwort has allelopathic qualities as it excretes substances that inhibit the growth of blue-green algae and phytoplankton.

Hiding place for fish, fry, and shrimp: Serves as cover and shade for inverts and small fish. It serves as a perfect hiding place for shrimp and fish.

Foraging place: Acts as a buffet of biofilm, which is an ideal first food for newly hatched fry and shrimplets.

Reduces nitrates: Helps in filtration, thereby reducing the load on the filter present in the tank. For example, according to the experiments, the Ceratophyllum demersum reduced ammonium and nitrate by more than 62% and 41.66% in 6 – 18 days. Note: Young plants, rather than older ones, are efficient in removing nutrients because they need these nutrients for their normal metabolic requirements.

Oxygenation: Hornwort oxygenates and aerates the tank water.

Interesting fact: Hornwort is used as a model organism for studies of plant physiology.

Difficulties and Problems of Hornwort

Hornwort may be easy to grow, hardy, and versatile; yet, having it in an aquarium comes with certain problematic conditions. Let’s have a look at some of them:

Hornwort turning brown: If you see something like brown, bronze, or copper color on the tips, this is often due to too much light in the tank. To combat this, tone down the light intensity and trim off the affected/ discolored leaves. Also, check to see if the water temperature is not too hot (more than 30C or 86F).

Needle shedding: This is a condition whereby the Hornwort sheds its needle-like leaves. This often happens when the plant is first introduced to the tank. After a while, the plant gets used to the tank environment and the shedding of leaves gradually decreases. However, if needle shedding lingers on for a long period of time, then it might be due to a lack of nutrients in the tank water or excessive lighting conditions.

Brittle leaves: Hornwort leaves are pretty brittle and cannot withstand pressure. It is easy to damage them during maintenance.

Yellow leaves: This is due to the lack of soluble iron content or insufficient light.

Fast growth/ Overgrowth: As a result of the rapid growth nature of the Hornwort, it will fill up the tank with ease. The plant will require regular stem trimmings from time to time to prevent it from overtaking the whole tank.

Do not use aquarium salt with Hornwort or it will lose all its needles.

You can also read “How to Spot Nutrient Deficiencies in Aquatic Plants”.

Unpredictable Hornwort

Although this part of the article also refers to problems, I still decided to stress it out. As you already know, Hornwort is super hardy and almost unkillable, once it starts growing in the tank. However, there are also many reports that aquarists have problems with keeping it alive at all. They say that it starts dying immediately after buying and introducing it to the tank.

How is it possible? Why?

Well, unfortunately, this is also true. In addition, to make it even worse, it can be really hard to pinpoint the reason! Personally, I think that:

Hornwort can have transplant shock, and maybe that is what happened. Give it some time.
Your water does not have nutrients. In this case, add some to the tank.
Unfair sellers could give you ‘wild’ Hornwort from a nearby lake, pond, etc. ‘Wild’ Hornwort can behave very strangely and sometimes cannot adapt to the aquarium ecosystem.

Hornwort and ‘Tankmates’

Keep in mind that Hornwort is a big plant that usually floats and blocks a lot of light from entering the tanks. Therefore, Hornwort is compatible only with plants that can survive in low-lighting conditions. For example, Java moss, American water weed, Anubias, Java Fern, Vallisneria, Sagittaria can be planted alongside the Hornwort.

In addition, I would not recommend planting other floating plants alongside Hornwort to avoid overcrowding and competition for vital resources. For example, the Duckweed can even outcompete Hornwort for light and nutrients.

Hornwort is suitable for community tanks that inhabit freshwater fish and invertebrates. The leaves of the Hornwort are hardy and do not have a smooth texture, because of this feature aquatic animals will have a difficult time trying to nibble on it. This makes it compatible with most fish species that will use it for their various activities like egg-laying, mating, hiding, etc.

You can easily plant Hornwort in a tank inhabiting the following aquatic species:

Fish (for example, Bettas, Tetras, Mollies, Zebra Danio, Platies, Guppies, etc.)
Snails (for example, Ramshorn snails, Nerite snails, Malaysian Trumpet snails, Japanese trapdoor snails, Mystery snails,).
Shrimp (All varieties of Neocaridina (Red Cherry Shrimp, Blue Velvet Shrimp, Snowball shrimp, Black Rose, Orange Sakura, Green Jade, Rili Shrimp, etc) or Caridina species (for example, Crystal Red Shrimp, Caridina cf. babaulti, Blue Tiger Shrimp, etc.), Amano shrimp, Ghost shrimp, Bamboo shrimp, Vampire shrimp, ). Basically, you can keep any shrimp species with it. They will love it!

Avoid keeping the plant with Gouramis, Oscars, Goldfish, and herbivorous cichlids. These fish species can damage the plant.

Buying Hornwort

Hornwort is widely available in most pet and aquarium stores. Here is what you should look out for when you want to purchase Hornwort for aquarium usage.

Healthy Hornwort should be bushy, having stems covered thickly in needles. It should be bright and vibrant in appearance. Avoid plants with few sparse needles.
The plant’s leaves should be uniformly green. Avoid plants with discoloration and brown or yellow patches.

Hornwort is inexpensive, $5-$10 can get you a bunch of Hornwort which should be enough for planting in a 15-gallon (60-liter) tank.

Note: There is no need to buy a lot of plants. In a month or two, you will have more than enough of Hornwort in the tank.

Quarantine Hornwort

When you have obtained some healthy plants for cultivation, you have to quarantine or sterilize them first (using bleach to get rid of parasites and treating them with alum to eliminate snails) before putting them into your tank!

They can have parasites, pests like snails, or even predators (dragonfly, damsefly nymphs, etc.).
They can be treated with chemicals (pesticides) to remove parasites, snails, etc. However, these chemicals are extremely poisonous to fish, shrimp, and other invertebrates.

To find out more, read my articles:

Note: Peroxide: Hornwort is very sensitive to peroxide. Never use it with this plant. It will shed off all the needles right away. However, it should survive aftershocks.

Conclusion

The common Hornwort is a popular plant used in the shrimp and/or fish-keeping hobby because of its hardy nature and versatility. This plant can be a great addition to your aquarium.

Beginners and experts in the hobby love this plant because of its easy maintenance and essential functions (filtration, heavy metals absorption, shade/cover).

Hornwort is easy to propagate and compatible with most kinds of aquatic species, therefore, making it one of the best plants to have in your aquarium.