I would like to increase stocks of a couple of different ferns I have, so I’m having a go at propagating them.  The process is the same for all ferns so I’m going to focus this post on the hart’s tongue fern, or Asplenium scolopendrium.  I have a small clump of it that I could divide but I hope to get a lot more by propagating using spores. I’ve never tried this before so I’m learning as I go.

Ferns evolved a different method of reproduction to other plants. They don’t produce seeds, producing instead spores which go through an intermediate stage before growing into baby ferns.  It’s analagous to reproduction by seeds, but subtly different and needs different handling as a result.

First job is to collect the spores.  In most ferns, these can be found on the reverse of the fronds. 

The brown blotches or stripes in this case are the spore containers.  I cut a few fronds from the parent fern and left them for a couple of days in the shed where it is dry, warm and out of the wind.  I just laid them spore-side down on clean white paper. 

After a few days, the spores have dropped off the fronds, leaving a shadow on the paper, which is actually the teeny fern spores. 

I’m so absurdy pleased by this stage that I could happily stop here. However, I press on. I collected the spores by carefully folding the paper and pouring the spores into a dry envelope. 

The intermediate stages of fern reproduction are apparently extremely sensitive to contaminants so it’s ultra important to be clean when “sowing” the spores.  I followed a commonly recommended technique that ensures the pot and the compost are thoroughly sterile.

With a pot of fresh compost standing by, boil a full kettle.  Fold a clean sheet of kitchen roll/towel, and place on top of the compost in the pot.  The kitchen roll is to stop the compost spattering all over the place in the next step. 

When the water is boiling, pour slowly over the kitchen roll until the kettle is empty. 

This may take a little while, and for obvious reasons I did this over a sink.  Repeat this twice, for a total of three times.  Remove the pad of kitchen roll and cover the pot immediately with some cling film or pop in a sealable bag, to prevent any contiminants entering the newly sterile pot.  I’ve heard the same effect can be achieved by microwaving the pot of compost for a minute or two on high power. I couldn’t quite bring myself to do that.

When the compost had completely cooled I headed off to the shed to “sow” the spores.  I’m not sure what the appropriate verb is.  I’ll use sow.  Remove the cling-film/open the bag, and gently and evenly sprinkle the spores (maybe the correct verb is sprinkle!) over the surface of the sterile compost.  

I popped the pot back in its plastic bag and left it in the heated bench.

The first things to appear should be something called a prothallus which look a little like liverwort, similar sort of organism in fact.  These are not baby ferns, but are the intermediate stage necessary to make a baby fern.  The prothalli have male and female components that do the necessary mingling which later results in something recognisably a baby fern.  In theory.  This mingling specifically requires water – the spermatazoa are swimmers not crawlers. This is why ferns are usually found in moist conditions. This means that the pot needs to be kept moist and certainly not allowed to dry out.  An occasional spritz with a fine spray of boiled, cooled water is recommended. I should see this intermediate liverwortesque prothallus phase after anything from 2 to 26 weeks, which is a bit vague as an interval! ‘Quite a while’ is what I took from that.

I’ll be back, with an update on progress and the next stage of this process, or if anything drastic happens.

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