Thursday, February 07, 2008

Fern Propagation

I've started up some fern propagation in my bathroom along the window ledge. It's brightly lit and warm there but at this time of year it gets no direct sunlight, which is pretty much ideal.

Fern Propagation

The spores I've sown are of:

Dicksonia antarctica Soft Tree Fern, grows to 4.5 m high.
Cyathea australis Rough Tree Fern, grows to 20 m high.
Blechnum nudum Fishbone Water Fern, trunk to 1 m.
Todea barbara King Fern, trunk to 3 m, fronds to 2.5 m.

All are indigenous to my region. It's a long and tricky process to grow ferns from spores, and I've not succeeded in the past--probably because I let the medium dry out. If this lot make it, it'll be decades before they reach full size.

Here's the procedure:
  • You can obtain spores by collecting fronds with well-developed sori, and place them face down on a sheet of paper in a place where draughts won't blow them away. The spores, which are are tiny and resemble fine dust, will fall out onto the paper over a few hours providing the sori are ripe.
  • Sterilise all pots, lids and saucers (I've used bowls). You can do this with boiling water, but try to avoid getting them contaminated while they're drying. I used a clean tea towel to sit them on.
  • Prepare your growing medium. I've used peat moss which I bought in a block and to which I added boiling water, to sterilise and hydrate it. You can also use sphagnam moss
  • Add the growing medium to the pots, and cover as soon as possible. You don't want bacteria or spores from fungi contaminating the material. If you don't have propagation pots with lids like those above, you can cover the pots with glass or clear plastic film.
  • Sit the pots into their saucers or bowls and water into saucer/bowl, partly submerging the pot.
  • When the pots have cooled down, remove the lids one by one and sprinkle on the spores. Cover again immediately.
  • Make sure that the medium doesn't dry out--keep your eye on the water levels!
Image source:
Australian National Botanic Gardens.
Illustration by Murray Fagg

As you can see from this diagram, the reproductive cycle of ferns is fascinating. It essentially has two generations that alternate, one being being gamete producing and the other spore producing.

The spore germinates to form a prothallus, a green speck only a cell thick in places, on the surface of the medium. It contains both male and female sex organs, and the male sperm fertilises the female egg and the new fern then grows out of the prothallus.
  • While the prothallus develops over the next 6 to 12 months, it's important not to allow any contamination to occur, so continue to water from below.
  • Once the ferns (fernlings?) emerge, you can start watering from above, using a mister or fine water sprayer. Again, only remove the lid briefly.
  • When a few fronds have appeared, you can prick the ferns out to avoid overcrowding, moving them into more pots and slowly hardening them off by gradually exposing them to the air. Keep them out of direct sunlight.
When I get to this point, I'll post more photos. Or photos of the whole lot contaminated with fungi and bacteria and rogue ferns because I've screwed it up!


Frances, said...

That is a lot of scientific info, may it help in your efforts. We have one type of fern that 'spores' itself all over the place, Japanese painted fern, athyrium niponicum, we play no part in this whatsoever considering it a gift from nature. We just don't tidy up the winter foliage, letting the new spring growth emerge from the old. The most fun is what drops from the windowbox, with baby ferns growing under it.

Frances at Faire Garden

Anonymous said...

Hi Margaret -

I've frequently suceeded in growing a range of ferns (maiden hairs & tree ferns etc) mainly by accident. I used to grow a range of Rhipsalis from seed using the "sphagnum in bag method" -- while I was moderately successful with the Rhips., I was astoundingly successful with the ferns (which I frequently weeded out!).

I take commerical sphag, blend it in a food processor to smallish bits. Fill pots with it and sow my seeds... I then enlose the bags in "snaplock" bags and voila! Ferns. I get the odd Rhip also :D!


Margaret said...

Hi Frances,

I looked up Athyrium niponicum--a lovely fern! We have plenty of ferns here that reproduce too, probably six or seven local species. But I guess the challenge was doing it myself!

Margaret said...

Yeah, okay, David. So it's dead easy with a plastic bag... But, but, um... my pots are prettier!!


Rachel Bozorth said...

Thank you for your post. I am currently trying to grow ferns from spores, although I have no idea what species they are (I came to possess fronds bearing ripe spores as sort of an accident, and immediately sprang into action trying to propagate them!).

I have seen numerous sources on collecting spores; however, I simply plucked individual leaflets off of the stem and set them spore-side down in the growing medium. Any comments on whether this might work? It seemed more direct to me. And when I tried to collect the spores on paper, I wasn't sure what was spore and what was not, and then I breathed and they all flew away! -- if I lived in a cave, I would probably have ferns growing from the walls.

I really want this to work, although as somewhat of a pessimist, I find it hard to believe that it will.

Please post again and let us know how your efforts are progressing.

Margaret said...

Hi Rachel,

Yes, it should work, I think, providing the sori are mature.

Sorry about the delay in responding to your post. I was jolted to do so because today I collected a fertile leaflet of Asplenium flabellifolium (Necklace Fern) and am collecting the spores as we speak. I'm doing it via the old sheet of paper in a dry, warm place method.

So far, I haven't had any success with the species I talked about in the original post--not a prothallus to be seen. I'm beginning to think that maybe the peat moss isn't the best medium. The water collecting at the base of the pots doesn't look great. I should check its pH. Just a gut feeling that that's what's wrong. So this time, I'm following David's recipe. I'm using Sphagnum moss, which I chopped up in the food processor (hey, nothing weird about me!), to see if that works better. If I more action this way, I'll start again with the other ferns.

Let me know when you see some action!

Anonymous said...

Hey Margaret,

I'm wondering how your tree ferns are coming along? Coincidentally, I sowed some spores at about the same time as you. Although, being in the UK, I didn't really have access to any parent plants to collect spores from. I had to cheat a bit, by buying them in a packet.

Anyway, after months of not a lot going on (except for convincing myself that an errant grass seedling was a baby fern), I recently noticed some mossy patches where the spores had been and today counted 5 prothallia! Each was about 2mm across.

Hope yours are doing well too! Thanks for the blog, it contains much useful info :-)

Margaret said...

Hi David,

I'm still waiting, alas! I'm hoping that when spring arrives and things warm up a bit in the bathroom, I'll get some action.

Some time ago, I thought I had germination, but as the green bits grew I realised they were only the sphagnum moss coming to life! Ah well, patience.

Glad to hear yours are working out. What species are they?