I’m developing a contained pond of Azolla. The aquatic fern that:
- Looks like a moss…
- Deters mosquito reproduction!
- Cleans and cools the air!
- Feeds plants and animals!
(Scroll to the end to see how I was able to keep a small section clear for looking at the reflection too!)
It loves full sun and warmth, but it’s also hardy to zone 4.
It can grow in just an inch or two of water. (Though this pond is 3ft deep.)
You can fertilize, or wait for algae to grow before adding it. I did both. A week after building the pond, algae started forming. I then added a little home-blended organic fertilizer (~7-7-7), just to get it started, and introduced the fern after stirring.
Letting birds poop and hang out there is great way to let phosphorous get added naturally, for the fern to use. (One is in the opposite corner pictured above.)
Why contained? Because it spreads over slow-moving or still water like crazy, creating a ‘net’ and blocking the surface. That’s why it fights mosquito reproduction so well.
Since it’s aquatic, it isn’t hard to keep it contained. Just keep its pond away from other water sources and features.
However, it can live beside other aquatic plants, if those other plants are already established (even just a little, Moss Fern is just a thin “ground”-cover).
For its many, many environmental and cost-saving benefits, Azolla is a much better choice when compared to Water Lilies or other large-leafed flowers for a pond, but if you want those in your pond, get them in first!
(I added native grasses and flowers two weeks before the Azolla).
It also provides a nitrogen source for the garden by living symbiotically with algae (and freshens the air a bit). Ancient records in China say it increased rice yields ~150%, where it has been widely used as a primary rice field cover crop for centuries.
To use as a nitrogen source either:
- Let its water (and a little of it) overflow into an adjacent bed when it rains.
- &/Or: Scoop up the water under/at the edge, from just under the surface, as a ready-made compost tea. (Mixing advised, especially for baby Starts.)
- &/Or: Harvest, 10% of it max, and add it to the compost bin. It’ll replace itself completely by the end of the week! It takes a bit longer to propagate than some ads would have you believe, but it is definitely a power grower!
Cleans Air & Graywater
This Scientific American article (not my favorite pub for every topic, but still a very useful resource) explains how Azolla cooled the entire planet millenia ago, by forming at the polar caps. They also give an example of people who feed it with Graywater, to clean the water. They could then make Graywater useful in the garden by using the Azolla.
According to Milkwood, Azolla is:
“-25-30% Protein, and low in lignin with makes it digestible to many animals, as well as nutritious
– Rich in essential amino acids, vitamins (vitamin A, vitamin B12 and Beta- Carotene), growth promoter intermediaries and minerals like calcium, phosphorous, potassium, ferrous, copper, magnesium etc.
– On a dry weight basis, it contains 25 – 35 percent protein, 10 – 15 percent minerals and 7 – 10 percent of amino acids, bio-active substances and bio-polymers.”
Moss/Mosquito Fern Propagation
In general, Ferns reproduce by spores, airborne (in this case waterborne), which grow into silly little plant masses called gametophytes. Each one is has an egg and some sperm (and closer to mammals’ than flowers’). Each spore is a different genetic version of the parent. They fertilize each other, either from a different fern (with haploid spores), or with themselves! (Using inbreeding avoidance strategies with diploid spores.)
(Click the photo for its source)
But, the Azolla differs. Its spores can be from a male sporangia (cluster of male spores); or be a female megaspore (pictured left looking rather vivacious), instead of each being bisexual. Each spore grows into a female gamaetophyte (which produces a few eggs) or male gametophyte (which sends out 8 sperm).
Just a cool tidbit of info!
My Moss-quito Fern Pond
I started with just 2 cups in the pond…
I then used this floating clear object to keep mosquitos out so I can still see the reflection too! (Vegetable-sourced plastic is a good option).
(You can’t cover the whole pond this way, because algae will take over! But you can definitely make yours bigger and snazzier than mine…)
It’s been a really fun and rewarding part of my increasingly-permaculture gardening!