Spore Propagation - Harvesting and Sowing
Growing your own tree ferns from spore is one of the most rewarding aspects of the hobby and yet it is also the most challenging. For this reason, very few people ever really get into spore propagation in a big way. So many of us have sown spore, waited for weeks for any signs of life only to lose our precious sporelings to mold or lack of humidity. It can be so extremely frustrating as to render your first effort your last!
My first effort began extremely well and within 3 months I had several propagators bristling with tiny little Cyatheas from all over the globe and yet in the space of a couple of weeks I'd lost the whole lot. This is a very common experience as in actual fact, getting spore to successfully germinate is fairly simple. It's the stages following those initial few tiny fronds when things start to get a little tricky.
In this first part we will look at how to harvest spore, how to store it and how to sow it.
Step 1 - harvesting ripe spore
If you live in the temperate regions of the world such as northern Europe and the north west U.S. then your tree ferns will typically produce spore in late summer and throughout autumn. In warmer and more tropical climates, tree ferns will produce spore all year round which makes availability less of a problem.
The spore will generally appear in the shape of round balls on the underside of the frond segments. Each one of these tiny little cases carries countless numbers of tiny dust-like particles which are the spore that we seek to harvest. This image below shows a fertile frond segment of Cyathea brownii with the clusters of spore cases.
But how do we know that the spore is ripe enough to harvest? Well that can be a little hit and miss at times. It is very easy to pick fertile pinnules which are not ready yet and equally as easy to pick those that have already shed their spore.
Many people will say that it's all to do with the colour of the spore cases; If they're green it's too early and if they're brown it's too late. That's a fair generalisation but not all spore cases are the same colour and shape. Some spore cases are jet black and some, like Todea barbara are only ripe when they're green!
My motto is this; if you're out in the bush on holiday somewhere and you don't know if you'll get another opportunity to pick from a fertile frond of Cibotium arachnoideum then for goodness sake take a few strips regardless of how they look!
However, If you're at home and watching your much loved Cyathea cooperi's every movement then you have the luxury of waiting and can choose your moment. If it was too early then simply wait another week and pick again.
Look very closely at the cases and you might see a tiny crack in them. That usually indicates that you're too late and equally if the cases appear a bit fluffy. Smooth and light greeny brown is a good sign but It's not an exact science and most spore growers fall into the first group of people who can't afford to be picky!
Step 2 - separating and storing spore
So how many frond segments do we need? Very few indeed. Each individual spore case probably contains enough spore to more than satisfy the hobbyist's needs. If I'm out on safari somewhere then I'll usually take just 3 or 4 segments and pop them into one of those little snaplock polythene bags of which I usually have a handful stashed in my camera bag. You really don't need more than this unless you want to keep a large stock, share with friends or it's that 'once in a lifetime' opportunity.
So having got our frond segments safely home we now need to entice the spore out of the case. This is fairly easy and can be done in two different ways.
If you have a few individual strips then the best method is to simply drop them into a paper envelope and seal it down. Alternatively you can lay them on a piece of paper and fold the paper up around the pinnules creating a make-shift envelope . Paper is far more preferable than a bag which can encourage condensation and those tiny spores will stick to the moist sides. Paper is ideal as it is dry and with a quick flick you can dislodge any spore stuck to the side.
The 2nd method is more commonly used when you have a larger frond segment which is too big for an envelope. Just place the frond, spore side down (ofcourse) on a sheet of A4 paper and place it somewhere out of the way where it wont get blown around. It often takes less than a day for the cases to open and the spore to fall out onto the paper. If nothing has happened after 1 week then it's unlikely that the cases were mature enough.
With a bit of luck when you lift your frond segment you will find that the spore has dropped and left a pattern identical to the shape of the frond pinnules. Likewise you will open your envelope and by peering in will see a line of spore and chaf along the bottom. But do we want the chaf? No, the chaf is particles of the spore case which dropped off when the spore was released. It won't do any harm but ideally we really need to get rid of these foreign particles and the method of achieving this is again fairly straight forward.
Spore, being so small tends to stick to the grain of the paper whereas the chaf does not. Hence if you gently roll the paper up into a U shape and tilt it forward onto another clean piece of paper the chaf will slide off leaving the spore behind.
You may need to repeat this process several times as more often than not you do lose some spore into the chaf pile. Single spores are virtually impossible to see with the naked eye and only when they are in a pile can you see how different they are to the chaf.
Keep separating the chaf until you have a nice clean pile of spore and don't forget to agitate the paper to dislodge all those spores which are lodged in the grain. You'll be surprised how much bigger your pile becomes when you do this!
Rarely do we actually sow spore the moment it is harvested. More often than not we want to keep it somewhere safe until we're ready to actually sow it. This may be because you don't actually want to sow it until the spring or maybe you just can't be bothered after all that effort you've just put in to separate the chaf!
Whatever the reason, it is important that the spore is kept in a fashion that won't allow it to become contaminated with mold spores. As we will discuss later, mould is the worst enemy of the up-and-coming young tree fern.
My personal favourite is to store it in those little snap lock bags that I mentioned earlier. I simply pour the spore in, push all of the air out of the bag and snap it shut. Some people use tiny paper envelopes and some use aluminium foil. They are all perfectly good methods.
If you intend storing your spore for long periods then it is beneficial to keep it in the fridge or in a cool and dry place. The reduction in temperature is said to prolong the viability of spore which in many cases can remain viable for several years if kept under these conditions.
Oh, and don't forget to label it!
