Marimo Moss Ball Care

Marimo Moss Balls are low-maintenance, beneficial aquatic plants that, like your pets, want to roll around, take baths, and need an excellent environment to thrive.

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Marimos are low-maintenance, beneficial aquatic plants that, like your pets, want to roll around, take baths, and need an excellent environment to thrive. They're loved worldwide, especially in Japan, where they're considered national treasures and heirlooms to many Japanese families. 
They don't move around or make cute eye contact, but they can be great companions that provide a soothing all-natural feel with a green and oceanic vibe. So, if you've recently bought one or are thinking of getting one, this guide below will help you take care of your marimo moss balls.

Marimo Moss Ball Overview 

Marimo came from the Japanese words Mari (ball) and Mo (algae). They originated from a few cold, freshwater lakes globally, most prominently Lake Akan in Japan and Lake Myvatn in Iceland. They're also prominent in lakes in Scotland and Estonia. 
Despite being called "moss," these plants are composed of filamentous green algae (aegagropila linnaei), so they're more algae balls than moss balls. They are soft with a fuzzy, near-velvety texture. They have an iconic spherical or round shape. Since they don't have roots or leaves, they move along with the waves and current. Sometimes they appear like free-floating filaments, like carpets. Other times, they're epilithic or grow on top of rocks. 
Marimo grows to about 12 inches in their natural habitat. However, some grew to over three feet, but it takes a hundred years or more to reach that size. Meanwhile, they can only grow up to six inches at home, with a growth rate of 0.2 inches or 5mm per year to get to that size. 
Since moss balls are adaptable to different water types, you can use tap water for their habitat. They can survive at least a month without water, but that's not ideal for them to be away from their habitat or enclosures that long.  
Because they're easy to maintain, you can just leave them in terrariums with healthy water and let them be. Don't worry about them dying soon because moss balls can live for a long time if you do the basic maintenance and create the right environment. 
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How to Create the Proper Environment for Marimo Moss Ball

If placed in a proper habitat, marimo moss balls can live for 200 years or longer, so setting up their enclosures is crucial.
The best container for them is made of glass to allow light through. You can opt for store-bought terrariums, but transparent glass jars are also a great alternative. Just make sure that it can contain at least a quart of water and is clean and sterilized. Containers with lids are perfect for minimizing dust or other particles that could contaminate the water. 
Although moss balls can adapt to different water types, they're picky with temperatures. The natural habitat of these plants has a temperature that ranges from lukewarm to cool, so it's best to mimic that in your terrarium. Marimos won't thrive in hot or warm water, so getting a tropical tank or placing them in one is not ideal. Never use distilled water since they need the minerals from natural water to survive.
If you wish to decorate your container with rocks, shells, or any similar material, rinse them first in hot water to remove dirt that may be harmful to marimos. If you use cleaning solutions like bleach or dish soap, make sure you don't leave any residue before putting the materials in the terrarium. These decorations are not vital to a moss ball's survival, but they make the environment livelier. 
Most houseplants are placed near windows where they can get sun exposure and have that breathable vibe at home. However, that's not the case with marimos. Direct light is harmful to them. So, place your terrarium where there's low, indirect light. Artificial lights like the ones from your home or in your aquarium are also excellent light sources. 
You can place them in fish tanks too. Moss balls help generate extra oxygen to help keep the water clean. They provide excellent habitat where your pet fish can hide and lay eggs. Plus, they provide food by trapping bits from the last feeding and reserving them for later.

Useful Tips on Ways to Care for a Marimo Moss Ball

Taking care of moss balls is easy. Since they don't grow new leaves, you won't have to deal with getting rid of dead ones. They don't need constant watering or repotting too. However, marimo moss ball care is not something you should take lightly. 
These are some of the essential plant care tips you need to keep in mind for your marimos: 


It might be surprising to know these aquatic plants need to be washed from time to time. If you're not keeping them with algae-eating animals, you need to clean them once every one or two weeks.
To do this, take them out of the water and wash them in lukewarm water one at a time. After rinsing, squeeze the ball gently on your hand a few times to discharge the old water before placing it back into the container. Squeezing the old water out will allow them to reabsorb the new and clean ones in the tank. 
Of course, if you notice a slight discoloration on your marimos, don't wait for a week or two. You need to clean them immediately. 

Water Change

You should change the water every time you take out the marimos for cleaning. However, if you notice that the water's getting warmer, you need to change it immediately for a cooler one. 
If you notice algae build-up in the glass, clean it out first before refilling and placing your marimos. Don't use any cleaning solution to avoid leaving any residue when washing the container. Use a brush or a sponge, and scrub off the dirt before rinsing the glass thoroughly with water. Make sure that the cleaning tools you're using are clean too. 

Salt Therapy

If marimos start to turn brown, there may be something wrong with their environment. If changing the water doesn't work, try adding salt to the container. Add a quarter teaspoon of aquarium salt or marimo salt to the terrarium to help the moss balls detox and return to their healthy state. 

Placing With Other Animals

Marimos are beneficial plants to a fish tank in many ways. For one, they absorb organic waste, nitrate, and phosphate, which helps keep the tank clean. However, some fish like to play with moss balls roughly or, in some cases, eat them. Crayfish are known for redecorating their tanks with torn-apart aquarium plants, so never partner marimos with them. 
The best tank mates for moss balls are betta fish. These freshwater fish love to rest on these plants and play with them without damage. 
Meanwhile, goldfish, axolotls, and freshwater turtles may coexist with marimos. But sometimes they play too much, causing significant harm to the moss balls. Axolotls may even choke on them since they suck prey and might accidentally eat marimos. You can place your plants with these pets but keep an eye out if they start breaking apart the balls. When they do, remove the marimos immediately. 
So, before you place them inside an aquarium, you need to know what type of fish you are keeping and how they act around such plants. 
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Naturally, moss balls are found on the bottom of lakes, where there's not much lighting. You should imitate this setup in their terrarium. Place them in areas with indirect exposure to sunlight or any normal household light. They're also happy with aquarium lights or lamps. Just make sure you flip them regularly to ensure all parts of it receive light. 


Like most plants, moss balls don't need trimming unless they begin to discolor. If you find discolored patches on your marimo, cleaning them or turning them to get adequate lighting should be the first thing you do. If the patches don't recolor, carefully remove the discolored parts by hand. Then, gently reshape them with your hands or roll them until they turn round again. 

Floating Marimos

Moss balls may float from time to time, but don't worry. During their photosynthesis, they trap air bubbles inside that cause them to float in the tank. To remove the bubbles, simply remove the marimos out and gently squeeze them to pop the air. When you put them back in the tank, they will sink to the bottom, but that could take a day or two. 


In the wild, moss balls experience asexual reproduction to populate. If one becomes too big, it breaks, grows, and divides. 
You can do this at home too. Take a ball out of the enclosure and squeeze any excess water off. Then, get a sterile pair of scissors and cut the ball into smaller pieces. Make sure that the new pieces are not less than one inch each. Then, roll them to make balls before putting them back in the tank. 
Keep turning the balls after every few days to make sure they grow evenly, but don't expect a complete growth in weeks. 
Remember not to expect your Marimo moss ball to grow too quickly. They only grow at least 5mm a year!

Potential Problems With Marimo Moss Balls 

Healthy moss balls are always bright green. That's all the sign you need to tell you that you're doing a great job taking care of them. Marimos have a way of communicating what's harming them through color, so you know what to do next. Still, it's handy to understand the different problems that could damage them. 
These are some of the potential problems that your marimos may experience: 

Poor Water Condition

Water hygiene is vital for marimos. If the water condition in your terrarium is poor, these plants will develop brown spots, which feel mushy when you touch them. Therefore, it's important to change your water from time to time to avoid discoloration. If the patches turn black, it indicates that the part of the plant is dead, and you need to remove them from the ball. 

Too Much Light

Lighting is also an essential factor in maintaining or damaging your marimos. If they turn white, they're overexposed to a light source. When that happens, move your terrarium to an area with less lighting and allow the plants to recover. 
No exposure to light is also an issue. If you find a brown patch on the bottom of the marimos, it's a sign that you're not turning them over to let them receive lighting equally. Turning them also helps maintain their round shape during growth. 

Dust and Other Particles

Containers with no lids are susceptible to particles falling into the water and contaminating it. If particles enter the water and reach the marimos, they will discolor slightly.
Simply clean the plants by taking them out and gently squeezing them in a different bowl with lukewarm water. Replace the water in their main containers as well before placing them back. Consider terrariums with lids to diminish the falling-particle problem.

Lack of Movement in the Water

Marimos get their round shape because they move along the waves and currents in their natural habitat. Make it a habit to gently add movement in the container to avoid them from flattening out. 
Try moving their enclosure around or making a back-and-forth movement with a clean spoon or any similar instrument to mimic waves, but be sure that the balls move when you do. 

Hitchhiking Animals

One recently discovered hitchhiker is the zebra mussels, which are known to be invasive species. They are infamous for damaging beaches, clogging water filtration systems, and destroying boat engines. They also filter out algae that are considered food for various native species. 
You might think these are problems you won't worry about at home, but improper disposal of zebra mussels could contribute to these issues. For instance, when you find one in your marimo and decide to flush it in your drain. That zebra mussel could make its way into waterways and start causing problems there. It's even hurtful if you're planning to grow a marimo-based business
The proper way to dispose of zebra mussels is by destroying the ball itself. There are four options for these: 
  1. Place the ball into a sealable plastic and free for at least one day
  2. Submerge the ball in boiling water for a minute
  3. Dilute a 1/3 cup of bleach per gallon of water, then submerge the ball for at least ten minutes
  4. Place in undiluted white vinegar for at least 20 minutes
Once you kill the marimo with zebra mussels, place it in a sealed bag and throw it in the trash. 

Visit Enter Neverland — The One-Stop Shop for Your Garden

Marimo moss balls are excellent pets to have. Taking care of them is easy with clean water, proper lighting, and constant care to keep their beautiful round shape and make sure they live for many years to come. Problems are easy to find through color, and they're easily prevented too. They're also great additions to a fish tank and a calming decoration at home. 
For all your marimo and other gardening needs, visit Neverland! Neverland is a one-stop-shop for everything gardening, from plants to accessories, connecting nature closer to people's homes.
Enter Neverland has everything you need to build your oasis from seed to flower pot, whether you're a beginner or a seasoned gardening pro. Contact us today!

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