When you notice java fern turning brown, the plant can face different stresses like transplant shock, improper lighting, mineral deficiency, and algae overgrowth.

Java Fern Turning Brown

Don’t worry; these problems are fixable. Stay till the end to learn about these causes and how to fix them easily.

What Are the Reasons Behind Java Ferns Turning Brown?

The reasons behind java ferns turning brown are usually when it faces light stress and mineral deficiencies. In addition, if you have recently transplanted it, it can also start having brown marks until it gets acclimatized to the new environment. Furthermore, algae problems can also cause ferns to turn brown.

– Transplant Shock

The plant is facing transplant shock if you have recently transplanted java ferns to a new gallon tank and are now seeing brown patches. It is a condition in which ferns take some time to get acclimatized to the new environment.

During the initial period, growers prefer both immersed and partially submerged approaches. So, when you transplant ferns to a new tank and the rhizomes (hair-like roots) feel any change, the uptake of nutrients can get slow. This will eventually cause browning.

– Too Much or Too Little Light

Java fern (scientific name Microsorum pteropus) needs approximately six hours of light to grow properly. Growers often ask if  it is okay to give java fern too much light? Well, no. If you use such a bulb that emits high-intensity light and turn it on for a long time, the plant leaves will turn brown.

The reason is that excessive light can kill some plant cells. When this happens, the spots will start to appear. To make things worse, the photosynthesis rate declines when the leaves start having spots. Plants will face many problems when this happens, and discoloration is one of them.

In addition, if ferns receive less light, the leaves can become brown. It is because proper light is critical for photosynthesis. So, leaves will become yellowish brown when it doesn’t occur smoothly.

– Incorrect Planting

It is best to be careful when planting java plants. Gardeners often make the mistake of planting them into the substrate, which is detrimental to plants. Java ferns and even java moss do not have any true roots. They have hair-like rhizomes that uptake water and nutrients for growth.

Causes of Java Fern Turning Brown

So, when you see java fern turning brown and yellow, the rhizomes are likely stuck in the substrate. First, the browning will start at the tips. Then, these Java fern brown tips will become gray, and the leaves will become brown.

– Lack of Nutrients

Aquarium plants are generally planted in substrates, but the java fern differs. The hair-like rhizomes absorb nutrients needed for growth directly from the water. Nutrient deficiency will occur if you don’t add fertilizers to the water every week.

When plants lack nutrients, their physiological functions will be affected. When this happens, plants won’t have enough energy to keep the green color. So, brown marks will start to appear on the leaves. After some time, you will notice the java fern turning black if the deficiency persists.

If you like to grow java moss with ferns, these plants will also face the impact of mineral deficiencies. You will also notice moss turning brown, along with ferns. After some time, both of them will become fragile and brown.

– Algae Problems

We all know that java ferns grow in water. So, algae growth can also occur in the tank – one of the biggest java fern problems. Algae do not directly impact ferns. Rather, it eats most of the nutrients you apply, causing mineral deficiency in ferns. It competes with light and other resources, too.

So, when the algae become dominant in a tank, the other plants will become weak with brown marks. The leaves can also drop off if the algae consume all the resources. Therefore, it is crucial to keep its growth in check.

– Nature

Sometimes, the dark brown or black spots on ferns are not worth worrying about. The spots are plants’ natural way to propagate themselves. Ferns multiply via apomixis – a process in which plants clone themselves.

From these dark spots, plantlets emerge. These plantlets will then develop new leaves and rhizomes. After this, these plantlets can be anchored anywhere. But if you don’t see plantlets coming out of these spots, ferns face different stress, and you should fix them immediately.

How Do You Fix Java Fern Brown Spots? 

To fix java fern brown spots, you should ensure plants enjoy an optimal light level for around six hours every day. You should also apply weekly liquid fertilizers – skip the granules – and control algae growth to stop the plants from getting brown.

– Give Plants Some Time

When you transplant ferns, and they start getting brown, transplant shock might be the reason. In this case, give plants some time. They can absorb shock within a week or two, and the growth rate will become normal.

– Provide Optimal Lighting Conditions

Java plants are sensitive to light stress. So, using the right bulb and placing the plants at an optimal distance is important. This will ensure photosynthesis occurs smoothly, keeping the leaves green. The recommended bulb for growing java plants is a 6700k spectrum bulb. Place plants at such a distance that they will receive optimal light on all parts.

Remember to turn the bulb on for at least six and not more than eight hours. It is because algae growth multiplies when you provide more light. So, note when you turn on the bulb and set the alarm at closing time as a reminder.

– Add Fertilizers Smartly

It is important to apply fertilizers to avoid java fern deficiency of minerals. Java plants, including java moss, do not require many nutrients. However, they are still crucial to maintain the green color.

Fixes for Java Fern Turning Brown

Experts recommend adding liquid fertilizers when you are growing ferns. It is because the medium in the tank is water. Therefore, when you add liquid fertilizer, it will mix quickly, and the minerals will be readily available.

– Keep a Check on Algae Growth

One of the most asked questions from java growers is how to stop algae growth. Well, getting rid of all the algae in the tank is impossible. However, you can do a few things to keep its growth in check.

You should ensure you provide only what is required (as algae love light). Furthermore, it is also recommended to change the water regularly. If you still see more algae, then manually remove the biofilm.

– Grow Ferns With Small Fish

A great way to grow ferns is to pair them up with small betta fish. It is because when these two become tank mates, everyone (including you) will get the benefits. So, what exactly happens when you grow ferns with fish?

The fish release carbon dioxide, which plants utilize to perform physiological functions. Java plants provide these fish a place to hide, cover, or rest. Furthermore, plants also release oxygen molecules, improving the environment for these fish.

You must choose an appropriate fish tank size and regularly check the water parameters. Doing this will let both the plants and fish live together peacefully. Ultimately, you will have a beautiful tank full of fish and green plants.

Conclusion of Java Fern Turning Brown


Now you know what causes java fern to be brown and how to fix the problem.

Let’s look at the main points to revise key details:

  • Provide java plants sufficient light for around six hours or expect them to change their color to brown.
  • Add liquid fertilizers every week to avoid mineral deficiencies.
  • Change the water regularly and remove the biofilm to control algae growth.
  • For better java plant health, grow it with fish.

Follow these easy points, and your java plants will thrive shortly!

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