The marimo moss ball aka Aegagropila linnaei—is not actually moss at all. In fact, it’s a freshwater, filamentous, green algal colony. First discovered in Lake Zell in Austria in the 1820s, the plant was later nicknamed “marimo” by Japanese botanist Takiya Kawakami in 1898. “Mari” means ball, while “mo” is a generic term for aquatic plants.
While these little cute balls of greenery were discovered in the 19th century, they’re actually much, much older: They evolved a billion years ago in the Neoproterozoic Era. To put that into perspective, there were no fish, animals, or plants during this time: It was just oceans of single-celled life.
Today, marimo are super popular in Asia, and we predict that they’ll be one of the trendiest house plants over the next few years, as they are super low maintenance and very photogenic.
How to Care for Marimo
Clean, cool water. For your marimo’s optimal health, use only filtered water, and make sure it’s room temperature or cooler.
Moderate to low indirect light. This is because marimo receive very little light in their native environment at the bottom of lakes. Direct sunlight can overheat your marimo, but artificial light is okay.
Change your marimo’s water about once every two weeks. When you do so, gently squeeze your marimo to remove any of the old water. Then, roll them back and forth on your palm to retain the circular shape. And don’t worry: They’re not as slimy as you think they are. They’re actually quite fluffy (and almost velvety) in nature.
Marimos grow very slowly—one or two tenths of an inch per year. The world’s largest recorded marimo is almost 40 inches in diameter, making it an estimated 200 years old.
Why is my marimo changing color?
Yellow or brown marimo is a sign something is wrong. It could be receiving too much sunlight or have an infection, or their water quality could have gone down. We recommend washing your marimo under running (tepid) water, and then replacing the water in their container with cool, filtered water.
You should also add in some aquarium salt. Note that you should never use table salt on your marimo—you can find aquarium salt at your local pet store. Be sure to place your marimo away from direct light.
How long can marimo live outside of water?
If conditions are ideal, they can live out of water for about a month. However, we recommend keeping your marimo out of water for a week at the most.
Is there any way to get my marimo to grow faster?
Marimo are extremely slow growers—be patient. However, lower water temperatures, better water quality, and an extremely diluted amount of fertilizer can help. More light also equals more growth, but be very careful not to overcook your marimo in direct light.
Can my marimo survive in a sealed container?
They can, but we recommend picking one with a loose lid, which will allow your marimo to breathe with its environment.
Marimo are sometimes referred to as love plants. According to Japanese legend, two lovers longed to be together—one was the daughter of a tribe chief, while the other was a poor commoner. When the chief forbade the lovers from being together, the couple ran away, fell into a nearby lake, and became marimo balls. Then, they were able to live together forever.
Marimo are meant to bring luck, love, and happiness to their owner. It is also believed they have the ability to heal a broken heart, so you might want to consider investing in some if you’re suffering from a bad breakup.
Find your very own marimo on The Sill.
The Sill is a garden shop based in New York City that specializes in indoor plants perfect for city apartments. At The Sill (or on their website), you can shop, learn, or work hand-in-hand with a dedicated Plant Specialist on a plant design and maintenance program.