Java Fern (Microsorum Pteropus): Ultimate Care Guide


The Java fern (Microsorum Pteropus) is a highly variable jungle plant that gets its name from the island of Java in Indonesia. Belonging to the Polypodiaceae family, this popular plant is commonly found in rocks, tree roots, and on the ground alongside streams and waterfalls throughout Southeast Asia. The Java fern has many variants, most of which can be found in Thailand, Indonesia, Malaysia, and the Philippines. And – as a true aquatic plant – the Java fern is able to grow while being fully or partially submerged in water.

The color intensity of the Java fern can range from medium green to dark green based on its light exposure. It features thick, lance-shaped leaves that hold up well in tanks with aggressive and plant-eating fish, which makes it an excellent aquarium plant. This plant is also great for providing fish with places to play and hide, as fish love to swim and hide in its leaves.

The Java fern is widely recognized as one of the easiest and most adaptable plants to grow in an aquarium and is a beginner-friendly plant that expert aquarists can also enjoy.

Types of Java Fern

There are many different types of Java Fern, and many of them are widely available in the aquarium hobby. Here are some of the most popular types of Java Fern.

Windelov Java Fern

Windelov java fern (also known as Lace Java fern) is a well-known Java fern variant that features long leaves with wispy tips, and grows up to 12 inches tall.

Trident Java Fern 

Trident Java fern is a less commonly found java fern variant that features leaves with frayed, fork-like tips.

Narrow Leaf Java Fern

Narrow leaf Java fern has thinner leaves than the regular Java fern. Its leaves are grass-like, and it can grow up to 12 inches tall.

Needle Leaf Java Fern

Needle leaf Java fern – like the narrow leaf Java fern – has long, thin leaves. Although the leaves of this variant are thinner and more ribbon-like than those of the narrow leaf Java fern. Despite its delicate appearance, the needle leaf Java fern’s leaves are thick and durable. This Java fern variant is rare and very difficult to find.  

Java Fern Mini 

As its name suggests, the Java fern mini is a miniature variant of the regular Java fern. Also known as the Petite Java fern, this compact variant grows up to about 6 inches.

Many more Java fern variants that can be found throughout Asia. Philippine Java ferns are found in the tropical Philippines and feature long, slender leaves that have a rippled, hammered texture. Latifolia Java ferns (also known as Java fern lettuce) have large, ruffled leaves and can grow to around the same size as the regular java fern.   

Java Fern (Microsorum Pteropus)
Java Fern (Microsorum Pteropus)

Java Fern Care

Because Java ferns can grow up to 14 inches tall, it’s important to choose an appropriate-tank size for them to flourish in. It’s generally recommended to place Java ferns in 10-gallon tanks to grow, although the seemingly ever-growing plant would likely need to be transplanted to a larger tank as it reaches its full maturity level and begins to propagate.  

Where to Plant Java Fern in an Aquarium

It is not recommended to plant java ferns under substrate material at the risk of burying their rhizomes, which could lead to the plants rotting and dying off. Java ferns are epiphytic plants, meaning that – instead of being rooted in the ground – they grow on other plants, trees, and structures for support. Unlike most plants that absorb nutrients through the roots, these aquatic plants take in nutrients through the leaves. Because of their epiphytic anatomy, java ferns need to be tied to rocks or driftwood (or float freely) to grow in an aquarium. (Continue reading to find out how to attach java ferns to driftwood.)

Fertilizing Java Fern

Java ferns do not require fertilizer to grow. They can absorb nutrients – along with carbon dioxide and nitrates – from water. This interesting fact about java ferns is what makes them excellent plants for regulating water conditions and helping maintain cleaner tanks for other tank inhabitants. But even though java ferns can absorb the nutrients they need from water, liquid fertilizer could be beneficial if a java fern is showing no signs of growth, in which case a good-quality fertilizer containing iron and potassium could help move the growth process along. Fertilizer also helps to treat java ferns that begin to show signs of nutrient deficiency.

Java Fern Lighting Requirement

Java ferns thrive in low to medium light. In fact, lighting that is too bright for java ferns can damage them, discolor them, and even cause burn spots to develop on their leaves. Nevertheless, these plants do require some lighting, as a severe lack of lighting could also be harmful to them and stunt their growth. To provide java ferns with enough lighting, it’s recommended to use 5000 –7000k bulbs to light the tank(s) that they will inhabit.

Temperature

The water temperature for java ferns should remain between 68 – 82°F.

Water pH

Water pH levels for java ferns should remain between 6 to 7.5.

Java Fern Growth Rate

Java ferns can take a year to reach their full size. They are slow-growing aquatic plants, growing about an inch per month, and producing one leaf at a time.

Java Fern Growth Height

Java ferns can grow up to 13 ½ inches tall.

Aquarium Co2 Requirement for Java Fern

Although they grow much quicker with additional CO2, Java ferns don’t need CO2 injections to thrive. In fact, java ferns are able to absorb the carbon dioxide that fish produce when they respirate in a tank. One instance where CO2 could be beneficial, however, is if the java fern is in a heavily planted tank with a lot of different plants that are also consuming CO2, as the additional CO2 would ensure that the java fern gets enough of to remain healthy.

Windelov Java Fern
Windelov Java Fern (Microsorum Pteropus ‘Windelov’)

Java Fern Propagation

Propagating a Java fern is a fairly simple process. When the plantlets on a mature plant have sprouted and developed tiny leaves and trailing roots, they can be clipped from the adult Java fern and attached to rocks or driftwood in the aquarium to grow on their own. Another common way to propagate a java fern is by dividing its rhizome. This process is done by cutting up sections of the rhizome to divide it into smaller pieces – allowing some leaves to remain on each piece – and then anchoring the individual rhizome pieces onto surfaces or objects to grow.

What is a Java Fern Rhizome?

The Java fern rhizome is comprised of dark, spindly stems situated between the leaves and the roots. The rhizome absorbs most of the water and nutrients that the plant needs. Rhizomes grow horizontally and enable the plant to attach to various surfaces. Rhizomes also play a major role in the asexual reproduction (or apomixis) of java ferns; each rhizome is divided into nodes that can grow roots to sprout into new plants if the rhizomes contain enough nutrients.

Do Java Ferns have spores?

Java ferns develop spores on the underside of their leaves that appear as brown or black dots. These spores will form a symmetrical pattern and have a bumpy-textured appearance. After a few weeks, the spores will grow into plantlets that are essentially duplicates of the adult plant.

Why is my Java Fern growing roots on leaves?

Mature java ferns can reproduce by growing roots known as adventitious sprouts on their leaves. The adventitious sprouts eventually grow into smaller copies of the mature plant, at which point they can even be removed and anchored to a separate object to grow into full-sized java ferns.

How to use Java Fern in an Aquascape

Java ferns are very low maintenance, as they don’t require added nutrients or need to be trimmed as frequently as faster-growing plants. They can withstand a range of water conditions and adapt to different environments. In an aquascape, these aquatic plants are best situated in the middle or background of the tank where they make aesthetically appealing, lush green accents. Because they have thick, durable leaves, java ferns hold up well against fish that like to nibble on aquarium plants and provide shelter for fish who are seeking a hideout or a shaded area. Moreover, plant-eating fish don’t particularly find the bitter taste of Java ferns to be appetizing.

Java ferns are adaptable to water parameters and can tolerate both soft, acidic water and hard, alkaline water. Commonly found near streams and waterfalls in their native habitat, java ferns can even thrive in tanks with strong water currents.

How to attach Java fern to driftwood

Although a Java fern is able to float in the water without being attached to anything, allowing the plant to float freely is not the best method for growing this plant. Because Java ferns are epiphytic plants, their roots will continue growing until they find something to attach and latch onto. This is why most aquarists choose to anchor their java ferns to rocks or driftwood.

Java ferns can be attached to driftwood by wrapping a long string of thread around the java fern rhizome and securely binding it to a piece of driftwood. The purpose of this method is to “train” the plant to remain anchored to the driftwood even after the thread disintegrates. When wrapping the thread around the rhizome, it’s important to avoid causing any damage and not tie it too tightly. This same process can also be followed when using fishing lines or rubber bands instead of thread. Although the fishing lines or rubber bands would need to be removed from the rhizome and driftwood once the rhizome has successfully anchored itself.

How to attach Java fern to rocks

When selecting rocks to attach java ferns to, it’s best to select rocks that have rough surfaces (e.g., lava rocks), as smoother rocks would take much longer for java ferns to attach to.

A very common method to attach Java ferns to rocks involves the unlikely use of superglue gel. Although this may sound like a strange or harmful solution that could potentially contaminate the tank, this method is actually used by many expert aquarists, and is a proven effective way to attach java ferns to various objects.

Attaching java ferns to rocks can be a hassle-free process when following these steps:

  1. Wash the rock to remove any dust or dirt from the surface.
  2. Thoroughly dry the rock so that the glue can adhere to it.
  3. Carefully apply a strip of super glue gel to the surface of the rock that is long enough to adhere to the length of the plant’s rhizome.
  4. Place the java fern in an upright position on the rock so that the rhizome adheres to the strip of glue.
  5. Press the rhizome in place for about 30 seconds so that it can successfully adhere to the rock.

Once this process is complete, the java fern will attach to the rock over time by securing its spiral-y roots around it, and the java fern rhizome will continue to grow and cover the rock.

How to plant Java Fern in substrate

To plant a Java fern in substrate, the roots of the plant should be meticulously placed in the substrate, so that the substrate material can weigh the plant down without burying the rhizome. It’s important that the rhizome – which is located above the roots – remains completely uncovered to prevent it from rotting, which could end up killing the java fern. Placing java ferns in substrate can be a tricky process, as it may be difficult to securely anchor the plant without burying the rhizome, especially if the tank is home to active and aggressive fish.

Can Java Fern grow out of water?

Java ferns are able to grow while being out of water. In fact, in their native environment, they are commonly found alongside streams and waterfalls where they have not been submerged in water. For a java fern to successfully grow out of water, however, it would need to be provided with plenty of nutrients, as java ferns mostly absorb their nutrients from water. Additionally, the java fern would need to be frequently spritzed with water or stored in a humid environment.

How How to trim Java Fern

Java fern can be trimmed by using a sharp pair of scissors to snip away any burned or unhealthy leaves that need to be removed. Lackluster-looking leaves on the java fern can be removed by cutting them off as close to the rhizome as possible. It’s very important to use a sharp pair of scissors when trimming a java fern to prevent any damage to the plant. If cut successfully, when a damaged leaf is removed from the plant, a new, healthy one will eventually sprout in its place. Dead leaves can also be removed by pinching them off at the base of the leaf where they connect with the rhizome. To limit the plant’s growth, smaller plant shoots can also be clipped off of the Java fern.

Why is my Java Fern Melting?

Java fern melt occurs when the plant begins to develop large dark spots before rotting and disintegrating into a mushy texture. This condition can occur if the plant has either: not received enough nutrients, been exposed to too much light, or been exposed to excessive amounts of blue-green algae.

Java fern leaves can also melt if a java fern has just been introduced to a new tank and has yet to adjust to the water parameters. In this situation, the older plant leaves will likely be the ones to show signs of melting, as they will have been impacted by the water parameter shift the most. This is no cause for alarm, however, because the older plant leaves will ultimately fall off and be replaced by healthy, more adaptable leaves.

How do I fix my melting java fern?

Java fern melt can be fixed by treating the plant with liquid fertilizers and making frequent water replacements until its condition begins to improve. If its deteriorating condition is a result of too much light exposure, it’s recommended to turn the tank lights completely off for a few days and limit its light exposure going forward.

How to prevent blue-green algae build-up

Blue-green algae is not actually algae, but bacteria, that resemble algae and produce blue-green scum. Blue-green algae (also known as cyanobacteria) usually occurs when there are high levels of waste in the water. The bacterium causes a slimy film to form all over the java fern and other parts of the tank, and can cause the java fern to melt. To prevent blue-green algae build-up, it’s necessary to replace 20% of water in the tank every two weeks, and stop excess waste from accumulating by not overfeeding the tank inhabitants. Blue-green algae build-up can also be prevented by reducing the light in the tank, as high lighting can also cause cyanobacteria to appear.

How to tell if a java fern is healthy

Although it’s natural for Java ferns to produce new plantlets on their leaves, it isn’t always an indication of good health. Java ferns can resort to making new plantlets when they’re under stress and unsure if the parent plant will survive. A good way to check the overall health of the Java fern is by examining its leaves.

A healthy Java fern will have bright to dark green leaves, and no visible browning. Although

black lines on the Java fern leaves can be mistaken for browning, they are simply the Java fern’s black veins and do not reflect the overall health of the plant. A healthy Java fern rhizome, like its leaves, should be dark green with no visible browning.

Why is my Java Fern turning brown?

The most common cause of browning in java ferns is a nutrition deficiency. To remedy this, the java fern would need to be treated with a liquid fertilizer that contains vital nutrients for plants, like calcium, magnesium, and potassium. In other cases, browning leaves could simply be dead leaves that will eventually fall off on their own.

Potassium deficiency is another common cause of browning in Java ferns. With potassium deficiency, Java ferns will develop tiny holes that will sometimes display yellow or brown coloring along the borders. To remedy this, the Java fern can be administered a fertilizer that contains potassium, or administered doses of a potassium-deficiency supplement for plants.

Why are there black spots on my java fern?

Black spots can appear on java fern leaves for various health reasons. Although before attempting to diagnose a plant that has developed black spots on its leaves, it’s necessary to determine whether the dark spots are actually spores. Spores develop as brown or black dots that are raised slightly and located on the underside of the leaves in a nearly symmetrical pattern. The appearance of spores on a plant’s leaves is no cause for concern and is a natural part of the java fern reproduction process. However, if the dark spots are not spores, they could indicate a nutrient deficiency in the plant – which can be resolved by treating it with high-quality liquid fertilizer. Black spots can also develop on a java fern if it has been exposed to too much high lighting, which can cause burn marks to form on its leaves.

Important Nutrients for Java Ferns

Java ferns need nitrogen, phosphorous, iron, magnesium, and manganese to grow. Although they absorb most of their nitrogen and phosphorous from food waste in tanks, if they begin to exhibit any of the signs of nutrient deficiency (such as browning or yellowing leaves), additional minerals may need to be added to their aquarium. Most broad-spectrum fertilizers will be able to provide Java ferns with the nutrients they need, but in some cases, nutrient-specific treatments can be administered.

Where can I find Java Fern for sale?

Java ferns are popular plants that can be found for sale online and in most local pet shops throughout the country.

Java Fern Price

Java ferns typically cost anywhere between $5 and $10. They are relatively inexpensive plants due to their popularity.

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