Marimo Care

Did you know...?

Marimo (Aegagropila linnaei), otherwise known as "Japanese Moss Balls", "Cladophora Balls" "Lake Moss" and many other names, is a type of filamentous green algae that grows naturally in only a handful of lakes, primarily in Japan, Iceland, Estonia and just recently Australia. They live on the bottom of the lake, where the gentle wave action and wind born currents keep them in motion and encourage their overall round growth. Each individual marimo is actually a colony of algae, with thousands of individual living strands. This, combined with their low light requirements and overall durability, make them a very desirable and easy to care for house plant.

Marimo are very popular in Japan, and have been declared a protected natural treasure. They have been gaining in popularity throughout the world as more people discover them, and recently exports from Japan have ceased in an effort to conserve a dwindling population of naturally growing marimo. To aid in this effort, a three day long festival is held in their honor every year. Today the majority of marimo are domestically grown in large aquariums.

Marimo terrariums (more appropriately aquariums), are a favorite item of ours. They are easy to establish, easy to care for, and just plain cool.

Caring for your marimo

Marimo are extremely easy to care for. Because they live at the bottom of the lake, they are adapted to very heavily filtered sunlight. In your home or office, they can be placed almost anywhere as long as they are kept out of bright or direct sunlight. Ideally they should be placed in a low to medium-low light spot. In most areas, they can be placed in regular tap water. If the water quality in your area is questionable, then filtered water or even club soda (the nitrogen is actually good for marimo) can be used. The water should be changed every 1-2 weeks or when fine algae filaments begin appearing, whichever comes first. Always fill your marimo container with cold water, and refresh if necessary during warmer months/in warmer climates. You can even place the marimo in the fridge to re-cool the water. Warm water will cause the marimo to suffer.

You should periodically poke at your marimo and move it around in it's container in order to rotate the side it is resting on. This will encourage it to grow round rather than oblong, and ensure that the all sides remain healthy. If it spends too much time on one side, the fibers on that side may turn brown from lack of light exposure.


No special fertilizing or nutrients are required. If your marimo seems to be struggling, place it in club soda in the fridge for a few days. This will often help boost it's overall health.


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