Can Elkhorn Ferns Survive Frost? My 8-Month Cold Climate Update

Almost a Year Later

Elkhorn ferns (Platycerium bifurcatum) are often recommended for warmer climates where they generally thrive.  I wanted to see if they could adapt to my colder garden conditions.  Around eight months ago I mounted several young elkhorn ferns around my garden to see whether they could survive and grow in my cold climate.  Some arrived in excellent condition, while others were already struggling.

I was not expecting to receive these elkhorn ferns, so was rather unprepared when they arrived.  I used string to mount them on scraps of timber, and used compressed cocopeat as the backing.  

If I were mounting these again, I'd use sphagnum moss and attactive staghorn mounting boards (they come in heaps of different styles, so I would pick my favourite looking ones).  I've linked the products I recommend near the end of this article for both Australian and US readers.

I am not an expert when it comes to elkhorn ferns and staghorn ferns, but I am loving growing them.  I wrote a previous post Growing Elkhorn Ferns in cold climate when my ferns were newly mounted.  I have grown Elkhorns when I lived in the subtropics, and also experimented with growing other Platycerium ferns from spores.   

After around seven or eight months, the results with my elkhorn ferns have been mixed.  A few have grown well, some have barely changed, and one didn't survive at all.  I am in a cold climate which is not ideal for growing these ferns, and it is currently mid winter so they are suffering a little from the cold, but that is life in my garden.

I thought it would be useful to show how each fern has performed so far, what I think helped the successful ones, and what I would do differently if I were starting again.

Quick Overview

Fern	Starting Condition	8 Month Result	My Thoughts
Fern #1	Two plants mounted together	One survived and grew	Successful despite pest damage
Fern #2	Poorly attached mount	Growing well	Surprisingly resilient
Fern #3	Already struggling	Died	Too damaged to recover
Larger fern	Temporary mount	Producing new fronds	Needs proper mounting

Elkhorn Fern #1: Survived Caterpillar Damage

The first elkhorn is surviving and somewhat growing.  This was two plants together, the one on the left died and the one on the right is growing well.  

Not long after I mounted this I noticed frass, and a caterpillar was in the plant on the left.  It ate the growing point and killed that plant.  Normally I would submerge a plant like this to drown caterpillars, but as I mounted on a plank of wood this was not an option.  I used fly spray, which did the job.  

Below you can see comparison photos.

This Elkhorn Fern Survived

This is what it looked like originally

Elkhorn Fern #2: The Surprisingly Successful One

I didn't attach the second elkhorn fern very securely, yet it has turned out to be one of the strongest growers.  The shield fronds have browned off somewhat, which is normal for elkhorns in my climate at this time of year.  It has grown several new foliar fronds that look healthy, and you probably can't see in the photo it is beginning to grow a new shield frond.

This fern has convinced me that elkhorn ferns are more forgiving than their reputation suggests, provided the growing point remains healthy.

Below you will see comparison photos from when I mounted it until now.

This Elkhorn Fern Grew Well

This is what it looked like originally

One Elkhorn Fern Died

Not Every Elkhorn Fern Survived.

This was looking poorly when I mounted it.  One day we had a storm with big winds, and this little fern was snatched away.  I searched for it, but it took me a few days before I found it.  When I found it, the fern looked dry and dead.  I mounted it again just in case, but it was dead and slowly degraded until it completely fell apart.

Below is the photo when I mounted it.  

This one was struggling when I received it

An Elkhorn Fern That Is Still Hanging On

The lowest fern I am not sure about.  When I first mounted it I was confused by its shape and looking back, I think I accidentally mounted it sideways.  This isn't great for them.  

This one elkhorn is still alive, and has grown new fronds.  I am not sure if it will survive, but I have hopes if it gets through winter it might pick up and grow well in spring.  

This fern isn't looking great, but could pick up

This is what it looked like when I mounted it

My Largest Elkhorn Fern Is Growing

I also have one large elkhorn fern.  I temporarily mounted it on a piece of timber using string, and put it in my unheated greenhouse out of the wind.  This one dropped some if its fronds.  Since then it started growing new shield fronds, and new foliar fronds.

This needs to be mounted properly, the string I used is too flimsy and is only doing the job temporarily because it is out of the wind.  

I put this in my greenhouse, and largely forgot about it.  I water it from time to time when it gets dry, and have every intention of mounting it properly.  Given it is winter, I don't want it to put on a lot of new growth until the weather warms.  In spring I plan to mount it better, and may keep it in the greenhouse as it seems to be doing well here.

My largest elkhorn fern is surviving

Elkhorn growing new shield fronds

Large elkhorn fern when I first got it

Frequently Asked Questions

What is the difference between elkhorn and staghorn ferns?

Elkhorn and staghorn ferns are closely related, but they are different species and the common names can sometimes be confusing and often differs between countries and regions.  In Australia, elkhorn ferns (Platycerium bifurcatum) are usually smaller plants that spread by producing pups, eventually forming large clumps.

Staghorn ferns (Platycerium superbum) grow much larger, usually as a single impressive plant, and they are not known for producing pups as readily as elkhorn ferns.

Can elkhorn ferns survive cold climates?

Yes, provided they do not experience many heavy frosts.  Mine have survived down to -5C so far under cover, and I expect temperatures to drop to -10C before winter is over. 

Do elkhorn ferns lose fronds in winter?

Sometimes mine lose foliar fronds over winter, and often the shield fronds brown off.  This is normal and they should resume growing once spring comes.

Can elkhorn ferns grow on timber?

Elkhorn ferns can be mounted on live trees, or timber, or plastic, and some people mount them on stones or tree fern trunks.  

Can Elkhorn Ferns Survive Frost?

Elkhorn ferns can sometimes survive a light frost, especially larger established plants, but they are not frost tolerant.  Sustained heavy frosts, like those we experience in my garden, would likely damage or kill them.

Mine have survived temperatures below freezing so far because they are protected from frost, but I would not expect them to tolerate repeated hard frosts without protection.  Low temperature is less problematic, frost is the issue.

Tips for Growing Elkhorn Ferns in Cold Climates

• Protect from heavy frost
• Keep them sheltered from cold winds
• Mount them where they can drain freely
• Reduce watering during cold weather

What I Would Do Differently Next Time

Looking back, my biggest mistakes were using string instead of proper garden wire, and mounting them quickly on a plank of wood I had in the garage because I wasn't prepared.  If I received another batch of young elkhorn ferns, I would have proper mounting boards, sphagnum moss, and wire ready beforehand. 

Products I Wish I Had Used

This post contains affiliate links. If you buy through these links, I may earn a small commission at no extra cost to you. I only recommend products that I use myself or would happily use.

If you're planning to mount your own elkhorn ferns, these are the materials I wish I had used for mine.  Had I more time and warning that I was about to receive these incredible plants, I would have bought:

For Australian readers:

Many people use sphagnum moss for mounting elkhorns.  I used coco peat because I had some in the garage at the time.  They both work for elkhorn ferns, but sphagnum moss is a better option. 

• Compressed coco peat blocks for the backing 
• Sphagnum moss for the backing 
• Staghorn mounting boards better than scraps of timber
• Plastic coated garden wire to secure the fern - far better than the string I used!
• Fish emulsion fertiliser to encourage healthy growth.

Products for US and other International readers:

• Compressed coco peat blocks for the backing 
• Sphagnum moss for the backing 
• Staghorn mounting boards better than scraps of timber
• Plastic coated garden wire to secure the fern - far better than the string I used!
• Fish emulsion fertiliser to encourage healthy growth.

I have not heavily fertilised these yet because they are still establishing and it is winter so I do not want much growth until spring and the weather is warmer.  I plan to fertilise over the warmer months, fish emulsion is commonly used by fern growers once plants are actively growing. 

Final Thoughts

While not every fern survived, I have been pleasantly surprised by how well most of these elkhorn ferns have adapted to my colder climate.  The healthiest plants are continuing to produce new shield and foliar fronds despite winter conditions, giving me confidence that they will perform even better once spring arrives.

I'll continue updating these ferns as they mature, particularly after another winter, to see whether they become fully established outdoors.

Related Articles

If you enjoyed following this elkhorn fern experiment, you may also enjoy some of my other plant and growing experiments, where I test unusual plants, propagation methods, and growing techniques in my own garden. 

• Growing Elkhorn Ferns in Cold Climate
• Growing Staghorn Ferns From Spores - 6 month update
• African Violet Wicking Pots Experiment
• Trampoline Fern Update
• Maidenhair Fern Variety Comparison

Growing staghorn Ferns From Spores: 6 month Update - Which Growing Method Worked Best

I experimented growing staghorn ferns (Platycerium superbum) from spores.  While they had good germination rates and they initially grew well, many refused to grow further until I divided and transplanted them.  I carried out this division around November/December 2025 when they were already about 12 months old.

Around that time, I separated and repotted my staghorn sporelings and wrote a previous post on the process of growing staghorn ferns from spores.  

Staghorn ferns grown from spores 

Growing staghorn ferns from spores can be a slow process, but it can be very rewarding once the plants reach the sporophyte stage.  I also wrote another update about their 3 month progress after division.  

It is now early June 2026, around six months since that division (meaning my spore grown staghorn ferns are now around 18 months old), and it is time to write another update on how these baby ferns are progressing.

This post may contain affiliate links, including Amazon Associates links.  As an Amazon Associate, I earn from qualifying purchases at no extra cost to you.

Staghorn ferns grown in seedling flat

These ferns did not perform well in the seedling flat.  Most eventually died, and the few that survived showed very little growth.  The humidity dome was helpful, not only to increase humidity,  but also protecting the tiny ferns from birds and temperature fluctuations.

The main challenge was moisture control, at times they were too wet, and at other times they dried out too much. 

From my experience, this setup is not ideal for beginners growing staghorn ferns from spores.  I won't be attempting to grow staghorn ferns like this again.

Small staghorn fern sporelings grown in a seedling tray after 18 months

Poor survival of staghorn fern spores in seedling flat setup

Humidity dome was helpful for growing sporelings

Staghorn fern sporelings in 24 cell tray

These spore grown staghorn ferns performed well.  Some died for reasons currently unknown.  Some survived but (again for reasons unknown) did not really grow much.  Others have grown large and strong.  I have high hopes these will survive my winter.

For beginners (such as myself), this method has been the most reliable so far.  I keep the trays under a humidity dome, like above.  This setup makes it simple to keep the humidity high, to keep the moisture at the right level, and basically keep everything going with little effort from me.

As the ferns mature, I will be able to open the vents to acclimatise them to lower humidity before eventually mounting them.

Over winter, even though they are under cover on my deck, it still can drop below freezing.  The humidity dome should provide some extra protection from the cold.  The dome should also help them get a little warmer on sunny days.  

This 24-cell propagation tray made moisture control much easier than my earlier setup (similar to this one). 

My staghorn ferns grown from spores

Some didn't survive, I don't know why

Some staghorn ferns survived and grew vigorously

Vigorous Platycerium superbum grown from spores in a 24-cell tray

Some spore grown staghorn ferns were larger

Other spore grown staghorn ferns were smaller

This setup worked well for growing staghorn ferns from spores 

Humidity dome helps staghorn fern sporelings 

Something unexpected happened in the 24 cell trays.  Spores that had not germinated over the past year have now started to sprout.

As shown in the photos, there are clusters of tiny prothallus emerging in several cells.  With any luck, these should grow and turn into tiny staghorn ferns.  Once they are larger, if they survive winter, I will be able to divide these and hopefully grow a few more staghorn ferns.

Given my success using the 24 cell trays in a humidity dome, this is the system I plan to use when dividing these extra spore grown staghorn ferns.

Staghorn ferns gametophytes and sporophytes

Some baby staghorn ferns are strong and vigorous

Growing staghorn ferns in wicking self watering pot

The staghorn ferns in the wicking pots all survived and have shown steady growth.  While they are not as large as those in the 24 cell trays, they have been much more consistent.

I keep these on a kitchen windowsill, where they receive stable light, more stable temperatures, and are easy to monitor.

For beginners, this has been one of the most reliable setups.  Watering is simple, humidity is easy to manage, and every plant I placed in these pots has survived so far.

I tend to use small wicking pots such as these.  They come with the pot, the base, and a wick.  I then used sticky tape and a clear container on top for humidity.  While the larger size pots would also work, I prefer the smaller size as they are great for several spore grown staghorn ferns, and I can also grow African violets and other plants in them. 

Every staghorn fern survived in a wicking pot

Wick watering pots make staghorn ferns from spore easy

Staghorn ferns in self watering pot

Staghorn fern sporelings prefer high humidity

If my staghorn ferns survive winter, I will think about trying to mount them in spring. 

Hopefully I will have some additional spore grown staghorns survive winter that I can divide and grow out. 

Frequently Asked Questions

How long does it take to grow a staghorn fern from spores?

In my very limited experience, it took approximately 18 months to produce plants of this size from spores.  This timeframe could have been a little faster had I divided them earlier.

Do staghorn fern spores need high humidity?

Yes.  While mature staghorn ferns need far less humidity, spore grown ferns appear to have different requirements.  All of my successful methods relied on maintaining consistently high humidity.

What is the best container for growing staghorn fern spores?

The 24-cell propagation tray produced the largest plants, while self-watering wicking pots produced the highest survival rate.

Can old staghorn fern spores still germinate?

Apparently yes.  Some spores in my trays germinated more than a year after they were originally sown.

What I would do differently in my experiment growing staghorn ferns from spores

If I were starting again, I would use the 24-cell tray setup from the beginning.  While not every plant survived, many did, and they resulted in the largest and most vigorous staghorn ferns.  These 24 cell trays didn't take much space, and were able to fit a lot of plants. 

As a back up, I would also use some small self watering pots, as they were so simple to use, and resulted in no losses.  These look nice on the windowsill, but can only fit a small number of plants.

For beginners like myself who are attempting to grow staghorn ferns from spores outside their preferred climate,  I think a combination of the 24 cell tray setup and some small wicking pots gives the highest chances of success. 

After roughly 18 months growing Staghorn ferns (Platycerium superbum) from spores, I found that high humidity is a key factor.  The 24-cell propagation trays produced the fastest growth, while self-watering wicking pots produced the highest survival rates.  If I were starting again, I would use both methods and avoid the seedling flat approach entirely.

I plan to post another update in spring, to show what worked and what didn't over winter.  I'm learning a lot from my little experiment growing staghorn ferns from spores, and hope my posts help someone else attempting this. 

Trampoline fern update

Last year I wrote a blog post on a fern that appeared under my trampoline.  It appeared by itself, I dug up a little one to try an protect in my greenhouse where it was eaten by rats or mice.  There were a few others under the trampoline, so I left them there and watered them.  They have grown a lot.

I don't know a lot about ferns, I currently don't even know the Genus of these ferns.  I am hoping a fern expert will point me in the right direction.  

Baby trampoline fern - this one did not survive

I try to water these ferns over summer when it's very dry.  I put bricks around the trampoline ferns.  These protect them from accidentally being mown over summer, and provide slight shelter from frosts. 

I pull out the grass and weeds around them when I remember.  There is too much shade under the trampoline for the grass to do well, so pulling out is usually pretty easy.

trampoline ferns protected by bricks

I had brought home some fertile fronds from tree ferns, and hoped to grow some sporelings.  Originally I hoped these ferns may have come from those spores.

The base of the fern was not looking hairy enough for any species of tree fern I am familiar with.  I am not familiar with baby tree ferns, so hadn't ruled out anything based on that.

base of ferns

base of fronds not very hairy

Still young, but growing

These ferns then started to spread.  They are not tree ferns.  

They are sending out above soil runners.  The runners are relatively thick, and sometimes they appear to branch a little.

I had hoped these were baby tree ferns that grew from spore.  The runners has shown this is not the case.  That's too bad, but it is what it is. 

 

Fern runners

Spreading by thick runners

The trampoline ferns have started to produce fertile fronds.  The shape and position of the sporangia should help identify the species.

Fertile fronds

If not tree ferns, I had hoped they could be hen and chicken ferns (Asplenium bulbiferum).  The runners and the lack of plantlets on the fronds indicates that it is unlikely to be hen and chicken ferns. 

Winter frosts will be here soon, the ferns will likely be burned down a lot but hopefully they will survive.  They survived last winter when they were smaller, this year they are larger and stronger, and will hopefully survive even if they sustain some frost damage.

Trampoline fern fronds

I like these little ferns.  Presumably these arrived on the wind as spores.  I don't know if they are a native species, or if they are exotic.  They burn back badly in the frosts, and need protection from sun, which does not help me narrow anything down very much.  

Hopefully one day I work out what species they are.  After winter passes, I will try to dig up some runners and grow them in other areas, but for now they can sit under the trampoline and slowly grow larger. 

Staghorn Fern from Spores: 3 Month Sporeling Progress

Around November/December I divided and transplanted my staghorn sporelings (Platycerium superbum) and wrote a blog post about these staghorn sporelings.  

I didn't really know what I was doing growing these from spore, so tried a few different ways to grow them.  Some are working well for now, others did not work.  

After about three months of growth there are some things to comment on so I thought I would write an update.

Baby staghorn fern

Staghorn fern sporelings grown in a tray

I had some staghorn sporelings growing in a tray, this did not work very well.  

I had too many problems controlling the watering.  We had big rains early on, which got into this and made it far too soggy.  I could not drain out the excess water, so opened the vents and hoped it would evaporate out.  Then it became too dry.  I didn't notice this until many of them had died.

There are still a few baby ferns alive in here, but most died. 

Most of these staghorn sporelings did not survive

Staghorn sporelings grown in 24 cell seedling tray

I also had a tray that I put in a different tray, this time it had a 24 seedling thingy.  

The moisture level in this was far easier to control.  When the rains got in, I could lift out the seedling thingy and tip out the excess water.  When this started to get dry it was simple to water by lifting it up and adding water underneath.

There were some losses, but not as many as trying to grow them just in a tray.  Some of the baby ferns are still tiny and do not appeared to have grown at all, others are getting large and looking pretty good.  There is a good chance some of these will survive the coming winter and be in a good chance to grow large next spring/summer.

There are some spots of mold and fungi, I am thinking of opening the vents to decrease humidity and see if that fixes it.

Some spore grown staghorn ferns are growing well

Baby staghorn sporelings getting large

Staghorn ferns in wicking self-watering pot

I had a few baby staghorn ferns in a self watering wick pot that is inside the house on the kitchen windowsill.  This always had moisture, but was never wet.  It also maintained 100% humidity and received bright indirect light.

All the baby ferns survived in there, and all grew larger.  They are not as large as the ones in the tray above, but they all look healthy.  These have a good chance of surviving the coming winter months.

100% humidity, bright indirect light

Not as large as I was hoping

Winter is just around the corner, so these may not have any more growth until spring.  Hopefully I can keep some alive until spring, and hopefully I can get a few up to size and be able to mount them some day.  

________________________________________

I wrote another update to show their progress, the staghorn ferns are getting larger and starting to look like tiny versions of the mature plants. 

Azolla the little fern that could

I've been growing this azolla (Azolla pinnata) since at least 2016.  It has been growing with us through drought, flood, snow, frosts, dust storms, and utter neglect.  

Remember that children's story of 'the little engine that could'?  It was a little train that kept going and going and going and when the hill got too steep it just kept going.  Azolla is like the plant version of this.  Very few plants have as many uses as azolla in a permaculture garden, and very few things are as simple to grow without posing a weed threat.

Azolla is simple to grow, incredibly productive (hence its ability to survive neglect), and I use it for a surprising number of things.  Very few plants have as many uses as azolla, very few plants are as simple to grow as azolla, an added bonus is this species is native to my area. 

While a few containers of azolla tucked under things around the yard can be surprisingly productive, each year I wish I had more azolla.  I consider increasing the amount I grow, but the reality of space and water constraints hits me and I only find space for a few more small containers of azolla. 

Azolla covering the water surface and forming a mat

Even though it doesn't look like a typical fern, azolla is a fern.  This little fern tends to float on the water surface with short thin roots dangling freely in the water, and does not ever need to touch soil.  Unlike many water plants, azolla can thrive in low nutrient water.  It is surprisingly resilient.  This species of azolla is native to Australia (and parts of Africa, and parts of Asia), and is the most common species of Azolla that can be found in my area.  

Azolla has a myriad of uses including animal feed, human food, mosquito control, fertiliser, mulch and compost, clearing water, providing honey bees somewhere to safely collect water, and plenty of other things.  I have eaten azolla, it isn't my favourite but in a pinch I guess I could eat it, that being said I would prefer to feed it to my chickens and then eat their eggs.  

If you ever have time to kill, look up the 'Azolla event'.  This is a time in the Eocene era were it is hypothesized that azolla growing in the arctic grew so much that it took so much carbon from the atmosphere that it changed the climate and caused an ice age.  Given that azolla can easily drawdown over 1.5 kg/m2/yr of carbon (some sources state it draws down 6.2 to 7.8kg per square meter), and the basin it was growing in covered around 4 million square kilometers, this hypothesis is plausible.  Sadly azolla will never be able to do this again, as the conditions that lead to this were rather unique, but it is fascinating nonetheless. 

Azolla and a rice plant

Azolla has a mutually beneficial symbiotic relationship with a blue green algae (cyanobacteria) called Anabaena azollae.  This is one of the few instances of symbiosis in nature being beneficial to both species.  To simplify what happens, the Azolla grows special little pockets to house the cyanobacterium and feeds it carbon, in return the blue green algae collects nitrogen from the air and turns it into a form that is usable by the fern.  Collecting nitrogen from the atmosphere like this is what makes azolla so useful. 

Not only is it rather rare to see mutually beneficial symbiosis, but this symbiosis is passed on from generation to generation and does not require re-inoculation.  To quote the Azolla foundation "we know of no other symbiotic relationship in which a cyanobacterium and plant pass down together during reproduction from generation to generation".  

Azolla also has a few other species of symbionts.  At this stage we don't really understand the purpose of those other species, or how they each interact, or if each is passed on or needs to be re-inoculated each generation.  It doesn't really matter too much, what matters is the azolla has various symbionts, and together they do a great job.  

Azolla and Chinese water chestnuts

I tend to grow azolla with aquatic vegetables such as Chinese water chestnuts.  I add some azolla when I plant them, and ignore it while it does its own thing.  Within a short amount of time the azolla covers the surface of the water.  From there it doesn't take too long to make a dense mat, which prevents mosquito larvae from being able to emerge and turn into adults.  

The azolla on top of the water surface also helps shade and cool the water, and somehow prevents the water from becoming too acidic.  Small containers can overheat in summer due to their small size, shading the water and shading the submerged soil helps keep the roots cooler which helps things grow better in the heat of summer.  

Azolla with watercress and brahmi

The mat of azolla also effectively blocks light.  This prevents algae from being a problem, and tends to prevent weed seeds from germinating.  

After the azolla turns into a thick mat, it starts to self compost.  New azolla grows on top, while the ferns underneath get smothered, and die.  This releases nitrogen and other nutrients that can be used by the water vegetables.  This works well as a natural organic biofertiliser.  This beneficial relationship between azolla and water plants was noticed hundreds of years ago, and azolla was introduced into rice paddies to increase rice yields and feed countless people long before the invent of chemical fertilisers.

The below container was partly filled with leaf litter, planted with a duck potato, topped up with water, and azolla added.  The soil level is too high, so there was not much space for water, but the azolla didn't mind, it grew well and covered the surface.  You can see the duck potatoes grew into large plants even though they were growing in small containers.  

Azolla and duck potatoes

The roots of azolla hang down in the water, and a myriad of life swims among them.  I don't know how these tiny things find their way into my containers, but I know if I look closely (or use a microscope) the roots are absolutely teeming with life.  

Tremendous amounts of research have been conducted into azolla.  All of this research points to azolla's productivity and ability to reduce the need for both chemical fertilisers and herbicides.  

While azolla is widely used as a biofertiliser in China and various other countries, it has not gained popularity in the Western countries where it is preferred to apply chemical fertilisers.  For backyard growers, azolla creates free organic fertiliser and free chicken feed.

Chinese water chestnuts growing in buckets with azolla

I start small aquatic vegetables in small pots of soil, then I transplant them into larger pots.  The ones in the photo below are in 10cm pots of soil submerged in a 4 liter ice cream container.  The azolla shades the water, which helps with temperature regulation and prevents algae from growing. 

Sometimes I place cuttings between these submerged pots.  The pots help hold the cuttings upright, keeping the base of the cutting under water, while the leaves remain in the air.  The azolla shades the water, prevents algae growth, and keeps the water cooler.  

Azolla with aquatic vegetables and cuttings

Recently I started to grow black forbidden rice (Oryza sativa).  I have some of the rice plants growing in pots of soil and being watered like any other vegetable plant, and some plants are in pots of soil submerged in shallow water.  I am curious to see which will perform better for me. 

In many countries azolla is intentionally added to flooded rice paddies.  Adding azolla is said to increase rice yields anywhere from 6.2% to 112% depending on which paper you read and what they are comparing.  All the research indicates that azolla helps rice plants grow larger, tiller more, and produce more grain (both in terms of weight as well as number of grains) per plant.  

I added azolla to most of the submerged rice I am growing.  It doesn't take long before the entire surface is covered.  Once the surface is covered it doesn't take long until the azolla forms a dense mat and starts to break down.  This should fertilise my plants, and provide food for numerous tiny water critters.  If nothing else, azolla will prevent mosquitoes from successfully breeding in these containers of still water.  

Newly planted Black forbidden rice with azolla

Azolla and rice - a few days later

The growth rate of azolla is pretty extraordinary.  

I took the photo below not long after adding azolla to the surface of the water.  You can see, the azolla is dividing and growing well. 

Black forbidden rice growing with azolla

I took the next photo of the same plants just six days later.  At this point the azolla had almost covered the surface of the water.  

This was towards the end of spring, over summer when the temperature is a little warmer the growth rate of azolla can be even faster.  

The rice plants seem to be doing well with azolla on the surface.  I am also growing a few rice plants in shallow water with no azolla to see if there is any noticeable difference.  I am taking photos and plan to write another blog post on this towards the end of the season.  While it is too early to make a call, at this stage the rice with azolla appears to be larger and more lush.

Six days of azolla growth

Azolla grows best floating on the surface of water, where it can double its biomass every few days.  Strangely enough, azolla can also grow long term on soil.  

Once I watered a pot using water that had a small piece of azolla in it.  The azolla sat on the surface of the soil and didn't die, and I decided to leave it and see what happened.  It stayed green and looked healthy enough.  

Over time the azolla grew, and slowly covered much of the soil surface.  This has not grown anywhere near as fast as when it is in water, but it has survived spring, summer, autumn, winter, another spring and is heading into its second summer.  This is long term survival.  

The azolla on top is growing, while the lower levels are mulching down.  The photos below are of the same pot of azolla, taken several months apart.  The first photo was taken after the azolla had been growing on soil for several months, the second photo was taken a few months after that. 

Azolla growing on soil long term

The same azolla still growing on just soil

From what I have seen, if growing on soil long term the azolla is a little tricky to get started, but once it gets established it is relatively hardy.  

The azolla needs damp soil and some shade to get started.  If I start by using free floating azolla and place it on soil it struggles.  If I get azolla that has started to form a dense mat, this seems hardier and tends to adapt to soil faster.  Once the azolla has been on soil for a while it changes slightly, it gets thicker and the roots change, and it seems to survive drier conditions and more sun.  

Interestingly, if I float some soil grown azolla on water, it seems to take some time to revert back to aquatic life.  For some time it just floats, it gets thinner, and does not divide.  Once it gets used to living on water, it then grows and divides like normal. 

Azolla growing on soil underneath dryland rice

As well as being excellent fertiliser, and great animal feed, azolla has a few other uses.  Honey bees and other small things need water in summer, but they can't always access water without drowning.  The bees can safely walk on azolla, and reach the water between the plants.  

Every summer I see a lot of bees on the azolla collecting water.  I also see butterflies standing on the azolla collecting water in the heat of summer.  

Dragonflies and other beneficial insects are also commonly seen around my azolla.  I am not sure if they are breeding in the water under the azolla, or if they are attracted due to the other insects, or if they are there for some other reason.  

Dragonflies are pretty, plus they are useful to have in my yard as they eat a lot of mosquitoes.  Whatever the correlation is between dragonflies and azolla, I am glad they are here.

Honey bee collecting water from azolla

Honey bee collecting water from azolla

For me, azolla performs best in part shade.  It certainly survives in full sun, but I find it grows faster when it has some shade.  Not surprisingly, being a plant means having too much shade will stop azolla from growing well. 

Azolla turns red when it is stressed.  This stress can be from too much sun, or from extreme temperatures.  When azolla is red, it grows slower, and is meant to be less nutritious.  While a pond covered in bright red azolla is a pretty amazing thing to see, I prefer to keep mine green and growing fast so I can use more of it for various things.  This normally means giving it a little shade.

Azolla starting to turn red from stress

Azolla and duckweed

Azolla spreads and divides fast.  It can double every day or so under good conditions.  

While azolla also reproduces sexually and produces spores like other ferns, the main way it reproduces is asexually.  Any part of azolla that breaks off has the potential to produce more azolla.  

While azolla prefers not to be frozen over winter, my azolla survives heavy frost, and has survived being frozen for days on end.  If it ever died from the cold, I have little doubt that either a tiny part was still alive, or sporocarps could be present in the water, and it could recolonise pretty quickly once the weather warmed.  

Azolla makes great chicken feed

I use azolla to supplement chicken feed, this helps the chickens stay healthy, and it lowers the feed bill.  

Azolla is surprisingly nutritious, and it is readily eaten by my hens.  As mentioned earlier the roots of azolla are teeming with tiny life, when my chickens eat azolla they also eat these tiny invertebrates.  

Studies indicate that azolla can replace up to 20% of bought food for layer hens without seeing a decline in eggs, but I can't grow that much azolla here.  I give them as much as I can as it replaces some bought food, and lowers the cost of eggs a little bit.  

Azolla is appreciated by hens over summer when there isn't much grass or other greenery available.  I can either float azolla on water, or I can scoop it into a dish, either way my hens eat it pretty quickly.  

Azolla and rice plants

While I am a little disappointed that azolla will never again be responsible for creating an ice age, I still like azolla.  I tend to find a lot of uses for azolla, and could use it a whole lot more if I had more of it.  I have to be content only growing a little bit as I don't have a lot of extra space.  

If you grow any animal feed, or have a garden, or grow water plants, or want to provide somewhere safe for honey bees to collect water, then azolla is for you.  Once you get azolla, you never need to buy it again as you can keep it going forever.  You may be able to find some azolla locally, or you may need to buy it.  You only need a little to get started as it divides fast.  Very few places other than dedicated water garden nurseries seem to sell azolla.  If you can't find any locally, I sell azolla through my for sale page.  

Azolla and Chinese water chestnuts growing in a bucket