Java fern (Microsorum pteropus) is an impressively durable plant that can withstand the likes of African cichlids, snails, and even those with the blackest of thumbs. It grows fine in tap water from liquid rock to near battery acid, can grow under regular house lights, can be attached or left floating, and is fine without Co2 or fertilizers.
There’s basically only one way to (realistically) kill it: burry the rhizome, the twig-like part of the plant between the roots and leaves. But, even when it starts to die, it does so incredibly slowly and is easily saved. Java fern dying shouldn’t be confused with melting or new plant syndrome. You can quickly tell if your fern is dying by looking for black or dark brown dots on the back of the leaves – these are the start of plantlets in a last-ditch effort to reproduce before it dies.
Java fern is one of my favorite aquarium plants, and I hope you’ll see why!
Table of contents
Java Fern FAQ
Can Java fern grow out of water?
Yes! It’is frequently grown out of water for the aquarium trade and is often the reason why it “melts” once introduced to your tank.
Why is my Java fern turning brown?
It’s likely your Java fern is melting. This can happen because the rhizome is buried, it’s been battling algae, or if it’s recently purchased and was grown immersed (out of water.)
Can Java fern grow in gravel?
So long as the rhizome isn’t buried, yes. You can also grow your fern by attaching it to wood or rocks, leaving it floating, or planting it in the sand – although sand is much more difficult.
Java Fern Care
Difficulty: Bulletproof
Size: 6 – 14″ (15 – 35 cm)
Propagation: Rhizome or advantageous plantlets
Fertilizer: Liquid
Speed of growth: Slow
Temperature: 64 – 86F (18 – 30C)
Java fern will grow if left floating but does much better if attached to a hard surface like rock or driftwood. Luckily attaching Java fern is a piece of cake (well, sometimes.)
Here are a few ways to attach your ferns to get the most out of them:
Anchoring With Superglue
This is by far my favorite method as I’ve found it to be the least frustrating one. If you want to go this route, find the gel version of superglue. I have used the exact one pictured so I know it’s safe, I cannot make recommendations on other ones since I’ve never used them, but I’ve certainly heard a horror story or two about superglue mishaps from other brands and formulas.
It’s as easy as take your plant, take your object, figure out how you want it to sit on said object, place superglue on the rhizome of the plant and placing it on the object where you want it. You’ll need to hold it for a few seconds until it starts to grip, and once it’s white, it’s good to go back in the tank. I’ve heard people can superglue plants underwater, but I’ve never attempted to put uncured superglue in a tank, so I can’t advise.
This method is super quick, easy, and gives the aesthetic result you want without a ton of hassle. The downside is that you’ll see the white from the superglue until the plant covers it or it gets covered in mulm (which seems to like to collect on it.)
This is the best option when you have fish that are, for lack of better term, plant aggressive or you’re trying to anchor the plant to a rock.
Anchoring With Thread
I’ve never had much luck with this method, and it only works well(ish) on thin pieces of driftwood. You take your thread, wrap it around the rhizome tight enough to hold the plant in place, but not so tight as to cut into the rhizome, and hope and pray it holds it.
The idea is, once the plant is fully anchored, the thread will deteriorate in the water and you’ll eventually be left with just a well-anchored plant. I’ve always found that when trying to attach plants to rocks, thread will not work. It’ll be too loose in most spots and the plant will eventually wiggle free of the string – this is especially true if your fish like to peck at/push/pull at the plant. Which most do.
I usually found the plant floating within a few weeks and had to fish the string out and superglue the plant down. Even when this method did work, I found that the roots took longer to establish and the plant never did as well as the ones that were superglued.
Anchoring With Fishing Line
The method for fishingline is basically the same as with thread; take your line, wrap it around the rhizome tight enough to hold the plant in place, but not so tight as to cut into the rhizome, and – again – pray it holds.
The only difference between the fishing line method and the thread method is that fishing line won’t deteriorate in the water. This is especially helpful if your root growth is super slow because you can wait until you’re sure the plant is anchored rather than wait until the thread decides to disintegrate.
Once you’re sure the plant is anchored, you go in and cut the line off the plant. I have had the same issues with fishing line that I’ve had with thread – the plant wiggles free, it’s never tight enough, it only works well on thin pieces of driftwood, etc.
“Planting” Rhizome Plants
Rhizome plants can be “planted” so long as care is taken not to bury the rhizome (so don’t actually plant it.) In tanks with fish that dig, sift sand, or otherwise like to disrupt the substrate, this won’t be a viable option unless you put the plant in a pot.
Planting rhizome plants in a pot is more difficult than one might expect, and you certainly won’t see the best growth out of them. Care needs to be taken to add just enough substrate in the pot to hold the plant’s roots down and act as a weight without burying the rhizome. And, again, if you have plant-aggressive fish, this option won’t be viable.
Making a Java fern mat or wall
Java fern can attach to basically anything, even craft foam! They’re usually too expensive to buy your way there and, if you’re starting from scratch, they take forever to grow in and start out clumpy looking, but the finished result is impressive to say the least. It offers a ton of hiding places for fish and fry and just looks lush and awesome!
If you opt for foam blocks, you can just superglue the plants on far enough away from each other to leave room for growth, secure the blocks (usually with a suction cup or superglue if you want a wall) and you’re done. This is also a great workaround for someone who wants a mat of Java fern under the substrate – if the foam block is thin enough you can place the substrate around the block to camouflage it and you’re good to go.
You can also sew some Java fern onto some craft mesh with the same space idea, although this is a flimsier and more time-consuming option.
Aside from anchoring, care basically amounts to benign neglect – leave it be and it’ll be fine. You can, if you want, try adding liquid fertilizers in small doses but, in most cases, it won’t need it and you may be tempting an algae-coated fate. The addition of Co2 would likely not benefit you any if you have just Java fern.
Once the root system of the plant is well-established, it usually explodes in growth, but trying to coax growth out of it beforehand is a fool’s errand. As far as I’m aware, there is no way to try to get the roots to establish or settle faster aside from anchoring it securely where it has space to spread out.
High-tech lighting offers a similar host of problems if you only have Java fern, as they’re slow-growing plants, this gives algae plenty of opportunities to take root (no pun intended,) which will drastically reduce the growth of your ferns.
Common Problems
It doesn’t tend to pose problems for folks often, but here are the few they could present for you:
Algae
Algae growth is a common problem, it will eventually choke out plants or outcompete them. Algae is a sign of an unbalanced ecosystem, either there is too much light or there are too many nutrients in the water, without one of these opportunities it wouldn’t be able to take hold.
Slow Growth
Slow growth isn’t a problem, per se, it’s a slow-growing plant. It’s more impatience that is the issue here. If your plant is floating, it’s worth anchoring it to get better growth. Aside from that, if your lights and your nutrients seem sufficient, it’s a waiting game.
Some plants, for whatever the reason, never seem to take off while others right next to them explode with growth. It could be that their root system grew in better or maybe their anchoring was better – whatever the reason – there’s no need to worry about it. If you’ve had the plant for, say, a year with minimal growth replanting or reanchoring it could be the solution.
Melting
Melting is incredibly common in aquatic plants as most of them are grown above water. If you pluck off the dying parts of the plant before they start rotting, the new aquatic growth should appear soon enough, and it’ll do just fine.
Maintenance
Unless you plan to keep your Java fern short or have a carefully curated aquascape (or your anchor keeps coming lose), maintenance is nonexistent. In the even you decide you want either of those things, maintenance is minimal at worst. Trimming the leaves and rhizome occasionally with be about all it takes to keep things in check.
Propagation
Propagation of Java fern, unless you plant to sell it or add plants to a different part of the tank, consists of letting it do it’s thing. Being a rhizome plant, it shoots new growth off the rhizome. If you look closely at it, you’ll see that one end of the rhizome is (almost always) slowly growing horizontally, from this horizontal growth, new vertical growth will emerge.
It also reproduces advantageous plantlets, you can see them forming on the back of the leaves as little dark brown or black hard, nubby dots. Eventually, these inconspicuous brown spots will form leaves and look like tiny Java replicas. When they’re ready, they’ll pop off and grow roots as they float around the tank and wait to be anchored. These plantlets are a sign your plant isn’t doing well and it’s either slowly dying or stressed. Counterintuitive, right?
It’s basically a last-ditch effort to ensure the species will survive. The plant thinks, if it could think, these babies will float off to better conditions elsewhere – not knowing in the slightest that your tank probably won’t provide those better conditions. While some people will tell you this isn’t cause for concern, it’s only partially correct, your plant isn’t dying – but it’s not in great condition, either. Maybe mild cause for consideration.
You can, of course, propagate your ferns by hand by plucking the plantlets off and letting them grow until roots form or using a sharp knife or pair of scissors to snip the new growth off the rhizome. If you chose to snip the rhizome, be aware that each section should be at least 2” (5 cm) long and should have some well-established root and plant growth. The cut section from the mother plant should continue growing horizontally and the new growth should start growing off the uncut section once settled. You can certainly create more than one cut if you plan on selling clippings, but I would advise to keep the sections longer so it (hopefully) reestablishes better.
Java Fern Varieties
All of these variants are Microsorum pteropus and are differentiated by their variant name (e.g. Microsorum pteropus ‘narrow’ or Microsorum pteropus ‘trident’.) Since they’re all the same species, they all have the same basic care requirements, although some “strains” are ever-so-slightly slower-growing or prone to melting.
Java Fern
The original Java fern variety, as a refresher, looks like this and grows about 14″ (35 cm) tall.
Narrow Leaf Java Fern
Narrow leaf has – you guess it! – narrow leaves. It’s also a shorter growing plant, topping out around 12” (30 cm.) The leaves tend to grow more vertically-inclined than regular Java fern, which makes it a great option for fish that enjoy spawning vertically (like angel fish.) The leaves also form a denser cluster of vegetation, making it easier for fry to hide.
Needle Leaf Java Fern
Needle leaf tops out at 6” (15 cm) making it a better option for low-maintenance aquascaped tanks if you want things to stay as you planted them. The plant resembles hair grass with thick leaves. It forms the densest growth of all the Java fern once established, but it can look a bit raggedy when you first get it in.
Trident Java Fern
Trident Java fern form stems that prong out, and those leaves prong. The leaf thickness is comparable to needle leaf, only more… prongy. This variant grows faster than the narrow leaf variant and stays about 10” (25 cm.) Single plants look similar to what I imagine freshwater kelp would look like, and mats form fantastically complicated mazes for fry and small fish to hide in.
Windelov Java Fern
Also called lacey Java fern, the leaves of this plant are smaller than the regular Java fern variety and the leaves tend to have a more even width (until you reach the frilly-looking tips of the leaves which spiral off into crazy formations.) They grow about 8” (20 cm) tall and mats of windelov form an almost flame-like appearance. Or maybe like a bunch of arugula leaves all standing straight up in a clump – either way, it looks awesome.
What Makes Java Fern – Potentially – The Best?
I mean… it’s bulletproof, need I say more?
Probably not, but I will. If you have a low-tech setup and a black thumb, Java fern will be your best friend. They also don’t need to be planted, which makes them ideal for breeder or bare-bottom setups. Once fully established, they’ll grow faster than you think (or than you’ve been told) and you can always sell excess Java fern for decent money to local fish stores or online. They also don’t require a ton of maintenance like trimming or fertilizer dosing, or iron, or any other crazy thing – which makes them the perfect plant for someone who wants to set it and forget it.
Beyond that, mats make an amazing display and a great hiding place for fry and, provided you set these up on a block, you can easily have massive mats in a breeder or bare bottom tank as well!
Uhm, again, they’re bulletproof. Or I assume so long as you don’t shoot the rhizome they would be.
Further Reading & Resources
Research Gate – Development of in vitro Sterilization Procedure for Java Fern (Microsorum pteropus)
USDA – Weed Risk Assessment for Leptochiluspteropus (Blume) Fraser-Jenk. (Polypodiaceae) – Java fern