The name of Marimo (毬藻, Aegagropila linnaei) originated from Japanese botanist Tatsuhiko Kawakami (毬 ‘mari’ = ball and 藻 ‘mo’ = generic term for aquatic plants). Native to previously glaciated areas of the world including Japan, Russia, Iceland, and parts of North America – the Marimo’s round shape is the result of freshwater lake motion. Marimo moss, as it’s known, is not actually moss at all, but a freshwater, filamentous green algal colony – that’s totally Instagram-worthy. Although Marimo live in water, they’re not as slimy as you’d think they are! They’re actually quite fluffy, almost velvety, in nature. We like to think of them as ‘plant pets’.
The lakes that Marimo have evolved in are alkaline, calciferous lakes. For the optimal health of Marimo at home, water should be filtered, alkaline, with a pH higher than 7. Because Marimo balls live at the bottom of lakes, and roll along the bottom with the current, they receive little light. In caring for your Marimo – try to keep it out of direct sun. An hour or so of direct sun is tolerable, as long as the temperature of the water stays cool. Freshwater lakes, especially at the bottom where Marimo live, are cold, and temperatures can range from 5C to 35C. Like most plants, Marimo do not like sudden temperature changes.
Frequently Asked Questions
1. How do I care my Marimo at home?
Clean, cool water – and minimal light!
2. What type of light source do I use?
Moderate to low, natural or artificial light will help keep your Marimo happy and healthy. An hour or so of direct sunlight is fine, as long as it is far away from a window, and the Marimo’s water doesn’t heat up.
3. Do I need to change the water? What water do I use?
Although tap is OK, we prefer to use either brita-filtered water, or bottled water that’s Fiji water or Icelandic water and has a guaranteed pH of about 7-8. If possible, change your Marimo’s water once every two weeks.
4. What should I do when changing water?
Gently squeeze your Marimo to remove any dirt trapped in it’s fluff, then roll your Marimo back and forth on a soft surface, like your palm, to help it retain its circular shape.
5. How long will my Marimo live?
Marimos are slow growers – growing one or two tenths of an inch a year. However, the world’s largest Marimo is almost 40 inches in diameter, making it an estimated 200+ years old. Your Marimo can last for decades with the proper care and environment.
6. Help! My Marimo is changing in color.
A yellow or brown Marimo is a sick Marimo. Your Marimo could be receiving too much sunlight, have an infection, or its water quality could have decreased. We recommend washing your Marimo under running water, replacing its water, and adding some salt. Make sure to use aquarium salt – not table salt! You can find it on Amazon, or at your local pet store. Add this directly to your Marimo’s container – about 5% of your water volume.
7. How long can a Marimo last without water?
If conditions are ideal – Marimos can live for one month without water.
8. Will my Marimo float or sink?
Your Marimo will spend its majority of time at the bottom of its container, like it would in its native lake environment. However, a Marimo does perform photosynthesis, and makes oxygen. These oxygen bubbles may make your Marimo float up to the surface of the water for a period of time. The more sun your Marimo receives, the more oxygen it will produce. You can also make your Marimo float by squeezing the water out of it, but we don’t recommend toying with them too often – they’re happiest when left to float or sink on their own.
9. Will my Marimo reproduce?
Your Marimo might reproduce when large enough and kept in a large container. You will see a bump growing on your Marimo – that’s a baby Marimo in the making. We do not recommend forcing your Marimo to reproduce by splitting it in two – more often than not, it will not be able to bounce back.
10. Is there anyway to get my Marimo to grow faster?
Marimo are slow growers! Be patient. Lower water temperatures, better water quality, and an extremely diluted amount of fertilizer can help. More light equals more growth, so a few hours of sunlight can also give your Marimo a boost, but be very careful not to cook your Marimo in direct light.
11. Can my Marimo survive in a fully sealed container?
A Marimo can survive in fully sealed container, but we recommend picking one with a loose lid, which will allow your marimo to breathe with its environment.
12. Fun Fact
According to a Japanese legend, there were two lovers who longed to be together. One, the daughter of a tribe chief; the other a poor commoner. When the chief forbade them from being together – the couple ran away, fell into the water, and became Marimo balls – able to live together forever. Because of this, Marimo balls, sometimes referred to as ‘love plants’, are thought to bring luck, love, and happiness, and have the ability to heal a broken heart.