The short answer
Keep the rhizome, the thick horizontal stem, uncovered. Tropica, a plant grower: “If planted in the bottom, do not cover the rhizome because it will rot.” Sources tie or glue the roots to wood or rock, or wedge it between stones; Aquarium Co-Op alone presses the rhizome into gravel, then pulls it back up so only the roots stay under.
Java fern (Microsorum pteropus) is a rhizome plant from Asia; our beginner plants guide compares its care needs with other easy species. These steps are for freshwater tanks.
Why the rhizome stays uncovered
Aquarium Co-Op, an aquarium retailer, calls the rhizome “a thick, horizontal stem or trunk”: “All the leaves and stems grow upwards out of the rhizome, while the roots grow downwards from the rhizome.” Three sources give the reason to keep it clear, each in its own words:
- Tropica, a Danish aquarium-plant grower: “If planted in the bottom, do not cover the rhizome because it will rot.”
- Aquarium Co-Op: “If it is buried under gravel or sand it will rot.” Its rhizome-plant page is softer: make sure “the rhizome doesn’t get buried in the ground or else the plant may suffer.”
- Buce Plant, an aquarium-plant retailer: “If you bury its horizontal rhizome beneath aquarium soil, sand, or gravel, the stem will suffocate, rot, and die.”
One ranking page disagrees. The 2Hr Aquarist, a planted-tank site that sells its own APT fertilizers, writes: “A long-standing myth is that you cannot plant Java fern into the substrate. You can plant it into the substrate as long as the substrate is well-maintained and not choked with organic waste.” 2Hr also says java fern “is more commonly used attached to wood or rock”. Our choice: the steps below follow Tropica, the grower, and keep the rhizome uncovered; this is not a finding that 2Hr is wrong.
Anchoring options, by source
| Planting method | Sources | Note |
|---|---|---|
| Tie to wood or rock | Tropica, Co-Op, Buce Plant | Tropica: “until it has gained a hold” |
| Glue the roots | Co-Op, Buce Plant | Roots, not the rhizome; diggers “might knock it off hardscape if not glued securely” (Buce) |
| Wedge between stones or roots | Tropica, Co-Op, Buce Plant | Tropica: “squeezed between stones or roots” |
| Roots in gravel, rhizome on top | Co-Op | Rhizome rests on the gravel |
| Left in its pot in a planter | Co-Op | Co-Op sells the planter |
| Plant weights | Buce Plant, its own | “Aquarium-safe”, per Buce |
| Floating | Co-Op | “will thrive while floating” |
Buce Plant sells its own “Aquarium-safe plant weights” to “loosely wrap them around the plant’s rhizome to prevent floating.” It says people call these “lead weights” but “our plant weights don’t actually contain lead”. Buce describes only its own weights.
What you need
- The java fern, in its pot or cup.
- Driftwood or rock; Co-Op’s gluing guide uses “any aquarium rock with structure”. Our driftwood roundup compares woods by type, with soaking directions where sellers give them.
- Fishing line or thread, or a super glue gel. Co-Op says to use “original super glue, not another type of glue” and to “Make sure it has cyanoacrylate”; Buce Plant suggests “gel-based superglue, such as Aqua Worx Omni Glue or any other aquarium-specific adhesive”.
- Sharp scissors and a paper towel. Co-Op welcomes gloves “to prevent your hands from sticking together.”
Prepare the fern: pot or tissue culture
Tropica sells standard java fern as a “Plant in 5 cm pot” (about 2 in; our conversion) and “grown on Mangrove wood”. It also sells its ‘Narrow’ and ‘Windeløv’ forms as 1-2-Grow! cups, which it describes as “very young plants cultivated and delivered directly from our laboratory”, adding: “The plants are guaranteed to be free from snails, algae and pesticides”.
- From a pot. Tropica: “If necessary, cut off the overgrown roots so that you can remove the pot and mineral wool.”
- From a 1-2-Grow! cup. Tropica: “Carefully take the plant out of the cup and rinse off the growing media under the tap.” Its next steps: “Split the plant in 6-8 portions using your fingers or sharp scissors (for small foreground plants).” “Plant portions into the substrate using tweezers.” Tropica does not say whether these steps apply to its java fern cups; our reading is that its rhizome rule above still applies (do not cover the rhizome).
When gluing several plants, Co-Op says to “do these within about 10-15 minutes because these are water plants that dry out quickly.”
How to attach java fern to wood or rock
Unplug before your hands go in
Fluval’s AquaClear filter manual: “Always unplug or disconnect all appliances in the aquarium from electricity supply before placing hands in water, before putting on or taking off parts and while the equipment is being installed, maintained or handled.” Lift out the wood or rock if it is already in the tank. Plug every appliance you unplugged back in once your hands are out.
Find a spot for the roots
Out of the tank, Co-Op says: “A natural crevice or dip works well.”
Tie it on
Tropica grows it “on a root or stone, attached with fishing line until it has gained a hold.” Buce Plant: “Tie the plant to the desired surface with cotton or synthetic thread. While effective, the visible ties may not be the most attractive option.”
Or glue the roots, not the rhizome
Co-Op: “Dry the plant roots by dabbing them on a paper towel or hand towel.” It spreads “a thin layer of glue on the rock the length of the rhizome and slightly thick”, then says: “Use the cap of the super glue to firmly press the plant’s roots into the glue”. Co-Op warns: “(Do not cover the rhizome in super glue or the plant may suffer.)” Co-Op’s hold times: its gluing guide says “about a minute or two”; its java fern guide “for 30 seconds, and then let air dry for another 3 minutes”; and its own glue’s directions “30 seconds or until set”. Co-Op’s directions for the super glue gel it sells: “Protect clothing and work surfaces, and use in a well-ventilated area. Keep out of reach of children.” “Point the tube away from your face and body. Do not squeeze the tube while puncturing. To puncture, screw the nozzle and cap assembly onto the tube completely.” “Apply the glue sparingly (one drop per squre [sic] inch) to one surface only.” “Also, use the outer cap to press the plant to the hardscape, since the glue does not stick to the cap.” Amounts and hold times differ; follow your glue’s label. Seachem, an aquarium products maker, warns on its Flourish Glue page: “WARNING: Cyanoacrylate. Danger. Bonds skin and eyes in seconds. Keep out of the reach of children. Eye and skin irritant. If eye contact occurs, rinse with water for 5-10 minutes.” That is Seachem’s own glue; with another glue, follow the warnings on its label, which is the final word.
Set it in the tank
Unplug every appliance in the tank first. Co-Op: “When they’re all dry, place them in your tank.” With your hands out of the water, plug every appliance you unplugged back in.
Or wedge it in place inside the tank
Unplug every appliance in the tank first. Tropica: “The plant can be tied on or squeezed between stones or roots.” Buce Plant: “Wedge the plant into natural gaps in driftwood or rocks.” Once the fern is in place and your hands are out, plug every appliance you unplugged back in.
Our aquascaping for beginners guide covers planning the layout and building the hardscape before you plant.
Planting it in gravel or sand without burying the rhizome
Press the roots in, then lift the rhizome
Unplug every appliance in the tank first. Co-Op: “Press the entire rhizome and all the roots deeply into the substrate. Then grab the leaves and stems, and gently pull the rhizome out until it is resting on top of the substrate while the roots are still inside the substrate.” Once the rhizome rests on top and your hands are out, plug every appliance you unplugged back in.
Or drop it in still potted
Unplug every appliance in the tank first. Co-Op, which sells the Easy Planter decoration: “A even easier way to plant your rhizome plant is to leave it in the plastic basket and rock wool and drop the pot into an Easy Planter decoration.” Tropica, by contrast, removes the pot and mineral wool. Once the pot is in place and your hands are out, plug every appliance you unplugged back in.
2Hr, which says java fern can go into the substrate, adds: “Java fern grows faster rooted in rich aqua soils, similar to other plant species.” That is aqua soil, not gravel or sand, and 2Hr’s photo caption reads: “Java fern ‘orange narrow’ 100 days growth while the rhizome is buried in aqua soil substrate.” The steps here follow Tropica. Our planted substrate roundup compares soils, gravels and laterite.
Light need and growth rate, by source
| Source | Light | Growth rate |
|---|---|---|
| Tropica | Low | Slow |
| Aquarium Co-Op | “Low Light 10-20 PAR” | “a slow grower” |
| Buce Plant | Low to Medium | Slow to Moderate |
| 2Hr Aquarist | “30-60umols of PAR is plenty of light” | Slow in low-tech tanks; “much faster” with CO2 |
The two Co-Op pages differ on light: its blog says “Any range from low to medium-high light is perfect for this plant. At the very high end range of light, you can actually burn or melt it.” Its product page: “Too much light may cause burning or excess algae growth, so if you are using a brighter light, consider placing the java fern further away from the light or under the shade of taller or floating plants.”
Choosing a light? Our planted aquarium light roundup compares eight lights by tank length. One pick is sold by its maker for “low-intensity plants”:
| # | Preview | Product | Price | Link |
|---|---|---|---|---|
| 1 |  | Marineland Advanced LED Strip Light for Salt & Fresh Water…Light (Marineland: "low-intensity plants") | $110.66 Prime | Check on Amazon |
Marineland Advanced LED, 18-24 in: Marineland sells it “For freshwater, saltwater, and low-intensity plants”, and the roundup suggests it for “Keepers of an 18- to 24-inch covered tank with low-light plants who want a set-and-forget timer.” Its caveats there: “Needs a glass or acrylic cover, per Marineland” and “No spectrum control beyond white and blue”. The roundup gives Marineland’s “PAR of 216 at 12 inches and 134 at 24 inches (air or water not stated)”. Co-Op’s band names no depth on its page (its linked PAR chart is for Co-Op’s own light, at 10-24 in), 2Hr’s none, and the roundup says: “Compare figures only at the same depth.” Co-Op’s advice above on brighter lights applies.
Plant care after planting
Feed it through the water, by the label
Co-Op: “Rhizome plants absorb nutrients primarily from the water column, so feed them an all-in-one liquid fertilizer as needed.” Follow your fertilizer’s label. Aqueon, an aquarium equipment maker, warns: “Do not use plant tabs or fertilizer sticks intended for houseplants as they may not have the correct balance of nutrients for aquatic plants.” The Shrimp Farm, a shrimp and aquarium retailer, gives its view: “Regular dosing with a high-NPK content fertilizer like Thrive can be beneficial for Java Ferns, but Flourish may not suffice for their nutritional needs.” And: “Always check the safety of fertilizers if you have shrimp in your tank.” Our plant fertilizer roundup compares what each maker says its fertilizer supplies, with each maker’s shrimp wording, and our guide to how often to fertilize aquarium plants sets makers’ schedules side by side. If fish look unwell after a dosing change, test the water and contact an aquatic veterinarian.
Tell sporangia from other dark spots
Tropica: “The black spots under the leaves are sporangia (reproductive organs), not signs of disease, as many believe.” Buce Plant: “Small dark bumps (sporangia) form along the undersides of mature leaves, sprouting tiny brown roots and mini green fronds.” Its care guide scopes this: “If the spots are uniform and appear on the underside of mature leaves, there’s nothing to worry about.” For spots elsewhere, see the next step.
Check brown leaves against the other causes
Co-Op: “Why is my java fern turning brown? It may be a nutrient deficiency, so measure the nitrate level using a multi-test strip.” It then gives dosing for its own fertilizers; follow your product’s label. Buce Plant’s care guide lists eight leaf problems under browning, holes and black spots: spores, nutrient deficiency (“especially potassium”), too much light, poor water quality and ammonia, a buried rhizome, old or melting leaves, curled leaves from a calcium shortage, and algae. Our guide to why aquarium plants turn brown covers browning in general.
Move plantlets when they are ready
Unplug every appliance in the tank first. Co-Op: “Tiny Java Ferns are formed at the edge of the leaves. Once they mature they drop off and attach themselves to wherever they should land.” Sources differ on when to take them: Buce Plant, “Once these baby plantlets develop 3–4 leaves”; 2Hr, “when they reach about an inch in size”. To split a large plant, Co-Op says: “Use a sharp pair of scissors to cut the rhizome and split into two plants.” Once your hands are out, plug every appliance you unplugged back in.
Trim melting leaves at the base
Unplug every appliance in the tank first. The Shrimp Farm describes java fern melt as a plant that “deteriorates rapidly due to extended periods of poor conditions or abrupt environmental changes. This manifests as leaves developing large brown or black spots, turning translucent or mushy.” Buce Plant: “Avoid making drastic changes to your water parameters or lighting because unstable conditions are the primary cause of leaf melt in new specimens.” Co-Op: “If the java fern has dying or melting leaves, trim them off at the base of the leaf without damaging the rhizome.” After trimming, with your hands out of the water, plug every appliance you unplugged back in. If the whole plant keeps declining, our guide to why aquarium plants die covers light, nutrients, planting and water.
Mistakes to avoid
The sources above name these: covering the rhizome with substrate (Tropica, Co-Op, Buce Plant) or glue (Co-Op); too much light (Co-Op, Buce Plant); treating sporangia as disease (Tropica); and, for new specimens, drastic changes to water or light (Buce Plant). One more, from Co-Op: “One needs to be careful about starting up a tank with Java Fern or pruning too much at once! Since this plant is such a slow grower, it can have terrible fights with algae.”
If your fish look unwell, test the water and contact an aquatic veterinarian. More setup guides are in our Tank Setup & Care section.
Ready to buy?
Our plant fertilizer roundup compares nine fertilizers, and our Substrate, Plants & Decor section gathers plants, substrates and planted-tank gear.
Frequently Asked Questions
Q. Do java ferns need to be planted at all?
Not according to Aquarium Co-Op: “Planting Java Fern is easy; simply throw it into your water.” It says java fern “will thrive while floating”.
Q. Can java fern grow in gravel or sand?
Sources differ. Co-Op suggests “burying the roots in some gravel” with the rhizome on top (above). Buce Plant answers its own question “Can I plant Java Fern into substrate?” with “No.” and says to attach it to rocks or driftwood.
Q. What fish can live with java fern?
Co-Op says of its thick, long leaves that “they can often survive in goldfish and African cichlid tanks”. The Shrimp Farm warns that “Species such as African Lake Cichlids and crayfish may pose a risk to the health of your plants.” Tropica says its ‘Windeløv’ form “is not eaten by herbivorous fish.”
Q. Does java fern need CO2?
Tropica rates its CO2 need low, Co-Op “none” and Buce Plant “Not Required”; 2Hr says “It does not require CO₂ injection” but grows “much faster” with it (table above).
Sources (8)
- Tropica (grower): Microsorum pteropus, ‘Windeløv’ 1-2-Grow!, 1-2-Grow!, Planting, Java fern on wood
- Aquarium Co-Op (retailer): Java fern guide, Java fern product page, Planting rhizome plants, Gluing plants to rocks, Super glue gel
- Buce Plant (retailer): Java fern, Java fern care guide
- Seachem (maker), Flourish Glue
- Fluval (maker), AquaClear manual
- Aqueon (maker), Aquatic Plant Basics
- The 2Hr Aquarist (fertilizer seller’s blog), How to grow Java fern
- The Shrimp Farm (retailer blog), Java Fern Care
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