Hygrophila Polysperma, also known as Dwarf Hygro, is an aquatic plant that is often used in aquariums. They are indigenous to India and Malaysia and may also be referred to as East Indian Hygrophila and Indian Swampweed. Hygrophila polysperma derives its name from the Greek words hydro, meaning “water,” and phila, meaning “love.”
It is infamous for its slow invasion into parts of Florida, eventually becoming invasive in the southern state’s tropical waters. A long, gangly aquatic plant reaching heights of up to 24 inches, it carries small, vibrant green leaves, which grow in alternating patterns opposite to one another. The Dwarf Hygro buds bluish-white flowers with two lips and sports a fascinating square-shaped stem.
Due to their invasive status in Florida, the plant has a long and complicated history in the United States, where it bears questionable standing, which will be expanded upon later. Even with its invasive label, Dwarf Hygro does have some notable benefits. It has been reported that its seeds have been used in medicine, and the plant itself is also commercially sold as an ornament. It may even raise water clarity in large numbers. This guide will explain how to care for this plant in an aquarium.
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How to Plant Hygrophila Polysperma in an Aquarium
Hygrophila polysperma is incredibly easy to grow. Simply pinch any part of the plant off, preferably the stem, and plant into the substrate. You can even use a single leaf from the plant. Make sure to leave plenty of space, as it will quickly grow and overcrowd other plants. Due to its quick growth rate paired with its maximum height of 60 cm, or 24 inches, it should be placed somewhere it will not interfere with other plants, preferably in the background.
Other methods include allowing a fully grown Hygrophila plant to reach the water’s surface and trimming the extra shoots you can plant. Hygrophila already requires a lot of trimming as part of its maintenance, so you will undoubtedly have spare leaves and shoots to plant. You can also take the same mature plant and cut it up into several pieces, allowing you to grow multiple simultaneously.
Hygrophila Polysperma Care
Most plants and animals require adequate sunlight, and Hygrophila polysperma is no exception. As a general rule, Dwarf Hygro can thrive even under low lighting. For best results, it will flourish under bright lights, such as a high-quality CFL, LED, or fluorescent light that outputs 2 WPG (watts per gallon). The run-of-the-mill aquarium light may be lower than this, which makes sense since low lighting is fine for raising fish. Plants, however, require more lighting to grow.
Time is also another important factor to consider. You may need to keep your aquarium lit anywhere from 8-12 hours daily. Consider the other aquatic life in the aquarium before doing so, as the species of fish and plants will require different conditions.
As for the condition of the water, due to its hardy nature, Dwarf Hygro can withstand a surprising number of environments. Dwarf Hygro will thrive in a wide range of temperatures, notably anywhere between 64 and 86 degrees Fahrenheit (18 to 30 degrees Celsius). This makes it a perfect plant for most aquariums, as little consideration is needed when planning one’s planted tank.
The levels of pH that Dwarf Hygro can comfortably live in sits as low as 5.0 and as high as 8.0. Seeing as how most fish live to do well in a neutral pH level (7.0), that may be your best option. Again, Hygrophila is quite resilient, which is worth considering as a decorative plant.
Hygrophila Polysperma Growth Rate and Height
As you may have guessed at this point, Hygrophila polysperma are not shy about anchoring down their roots and rapidly multiplying. In an environment filled with adequate lighting and abundant nutrients like trace minerals, Hygrophila will grow at an astounding rate, growing up as much as two inches in the span of one week.
It is worth noting that they are not often suited for smaller-sized tanks. As mentioned earlier, Hygrophila polysperma can grow up to 60 cm (24 in), so it is advised to keep them in a medium or large aquarium, the absolute minimum being about 10 gallons (or about 37.8 liters).
Owing to their tremendous ability to grow and propagate rapidly, it is vital for owners of Dwarf Hygro to maintain a habit of trimming them down to a medium height, as they will quickly overtake their aquarium environment. You may also find it helpful to clean up any dead leaves found at the lower half of the stem to maintain its appearance. Trimming down your Hygrophila is beneficial not only for the surrounding life but also for the plant itself. Trimming encourages growth and rejuvenation, leaving a healthier and more beautiful plant.
Now, Hygrophila’s immense growth rate may seem entirely like an impediment to your aquarium life, but it does bring something to the table besides acting like the rabbits of the aquatic botanical world. Hygrophila’s large presence and fast growth actually soak up any leftover nutrients needed for algae to grow in your aquarium. As a result, Hygrophila helps prevent the growth of these murky microorganisms.
How to use Hygrophila Polysperma in an Aquascape
Adding Hygrophila polysperma to your aquascape may seem daunting after all the information you just read, but it is doable and worth the effort. First of all, placement and spacing are absolutely crucial to maintaining an aquarium that has to juggle both fish and plants. As mentioned earlier, Hygrophila works best when decorating the background of a tank, where its long stem and leaves do not block your view of the fish and decor.
It works well in sand, gravel, and aquarium soil. If you have a large tank, you can experiment with planting it in the middle of the tank. After it begins to sprout, you can either keep it there or move it to the back. Just keep in mind that it requires a lot of pruning, so if you plan to keep it in the center of all of the action, attention to pruning its shoots and leaves is a must. If you can give your Hygrophila the time and attention it needs, it will reward you with lustrous, aqua-green vegetation that will bring a natural and earthy charm to your aquarium.
How to Create a Hygrophila Polysperma Carpet
Hygrophila polysperma is not commonly used for carpeting, as its fast growth rate means you will have to trim it regularly to prevent it from getting too high. This weakness, however, is also its strength. One of the most frustrating parts of carpeting is its slowness. People tend to use other plants, but Hygrophila will yield faster results in comparison. For this, we will use the Dry Start Method, resulting in even quicker carpeting. You can buy hygrophila seeds, but it might be easier to use any part of a mature plant simply.
First, begin with an empty aquarium and layer the bottom with either soil or sand for the substrate. Decorate the inside of your aquarium as desired and spray down the substrate with water to get it moist. You are not going to want to over-hydrate your soil or sand. When you finish, there should not be any pools of water, only a darkened substrate. Next, plant the hygrophila pieces into the substrate, and cover the top of the aquarium with plastic wrap, which locks in the moisture.
For the next couple of weeks, you will have to provide moisture and light to your tank until you begin to see the hygrophila spread and take root. The plastic wrap is going to stay on your tank for the duration of this time, only coming off for hydrating and for half-hour breathers that will help to prevent mold. You will need to moisten your soil 2-3 times a day and provide it with 12 hours of light from an aquarium or gardening lamp. Make sure to check on it so that it doesn’t go dry. Otherwise, you’ll have to start over if the plant dies. How long this process takes will vary, but Hygrophila grows like no other. When you start to see results, you can fill the tank with water and proceed to set up the rest of the tank.
Can you Grow Hygrophila Polysperma Emersed?
Most Hygrophila grow emersed in the wild and aquariums, and Hygrophila polysperma is no exception. Unattended hygrophila will not only grow and expand horizontally within the confines of its aquarium but also begin to peek over the surface of the water if there is no cover on top. In the wild, Hygrophila grows both in and out of the water, further showing its hardiness.
Is Aquarium Co2 Injection Necessary for Hygrophila Polysperma?
Hygrophila polysperma is robust and hardy enough to live in most aquarium settings without the need for additional aid. Although CO2 would definitely give the plant a boost in growth, it is not necessary, and as a matter of fact, may even be a detriment to your aquarium. Hygrophila, on its own, tends to dominate tanks if left to its own devices. CO2 and other growth enhancers, such as mineral supplements, can be left out. That is unless there is another plant life that needs the boost.
Hygrophila Polysperma Types
There are a few types of Hygrophila Polysperma that are common in the aquarium hobby. This includes Hygrophila Polysperma Sunset and Hygrophila Polysperma Ceylon.
Hygrophila Polysperma Sunset
Also going by the name “Rosanervig” in Europe is a variant of Dwarf Hygro that was named by a Danish aquatic plant nursery known as Tropica. One defining characteristic of this variety comes from its white-colored veins. This is caused by a virus targeting the Rosanervig plant and preventing the tissue around the veins from photosynthesizing. What sets it apart visually from regular Dwarf Hygro is the fact that it has a deep red tint to its leaves and white veins, giving it a unique and beautiful look among the other varieties.
Hygrophila Polysperma Ceylon
This unique variety originated from Sri Lanka and was first cultivated in the year 1977. The distinct bronze shade painted on its leaves sets it apart from its brethren. This Autumn-like brown appears when its environment has sufficient amounts of iron.
Is Hygrophila Polysperma illegal in the U.S.?
Hygrophila polysperma is on the USDA Federal Noxious Weed List and the FDACS-Florida Prohibited Aquatic Plant List due to its high invasion risk. Dwarf Hygro has a rocky history with Florida, where it quickly spread and became an invasive threat to the tropical ecosystem in the southern part of the state. As a result, it is impossible to buy, sell, or import the plant. So if you live in the States, you are plum out of luck. It is sold commercially in other countries, such as the Danish run botanical business Tropica.
Don’t let Hygrophila polysperma’s rapid growth and environmental history scare you away from this wonderful plant. Its strength also just happens to be its greatest weakness. In the wrong ecosystem, it can go awry, but it also has the potential to produce medicine, help in the fight against aquarium-borne algae, make speedy carpeting, and with its beautiful leaves that come in vibrant colors, it’s hard to turn your back on it.
Even though it may be limited to aquarists outside of America, hopefully, it will one day make a reappearance in public aquariums, where it will finally get the opportunity to flourish and show off its natural beauty.