Ferns - collecting and sowing spores

Submitted by Tim Ingram on Sun, 08/26/2012 - 09:11

I am not a great expert at growing and raising ferns from spores but we do grow an increasing number of species in the garden and they are fascinating to propagate. Early autumn is a good time to collect spores and this is an example from a frond of Polystichum acrostichoides left to dry out for a day or two between two sheets of paper. This fern has sori running all the way along the pinnae (which is what gives it its name) and hence the spores have been deposited in lines. When sori are more familiarly distributed discreetly on the underside of the pinnae you can get a beautiful impression of the frond from the released spores. I am particularly keen on many of the smaller alpine genus like Woodsia and Asplenium so hope to get success in raising some of these.

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Submitted by Palustris on Sun, 08/26/2012 - 10:27

If anyone is interested, this is a piece I wrote many moons ago on growing Ferns from spores.
Fern Spore Sowing.

The first, second and third essential is sterility of every part of the growing system (except perhaps the grower!).
This is the method I used and it worked for me, no doubt others will have their own system.
1.I use new plastic 7cm. plant pots and sterilise them by immersing them in boiling water for about a minute. (Test one first to make sure it does not lose shape. Otherwise you must cold sterilise with a mild bleach solution.
2. Any seed sowing compost is OK. Fill dry, cool pots to about an 1 cm below the top and firm down gently. Cover the top with a piece of kitchen towel or coffee filter paper. Pour boiling water through the paper. About a cupful will do.
3. Cover the pots and allow to cool. No further watering is necessary. Remove filter paper.
4. When cool sprinkle fern spores on the surface. Each pot will be big enough for about as many spores as you can fit on the tip of a penknife. They are very tiny and really do need to be spread thinly on the surface or they will not have room to develop. DO NOT DO THIS IN A WINDY SPOT! or sneeze.
5. Place pot in a plastic bag and seal. I use sandwich bags and the paper ties which come with the roll.
6. Place in a warm (unless they are hot house ferns, in which case they need more heat) light position. A north facing or shady window ledge or in the greenhouse but put some shade netting over the top.
7.Eventually the surface of the pot will become covered in what looks like moss (if it is going to work). Open the bag and spray the surface of the 'moss' with distilled water( take the chill off it). Close the bag and put back in a warm, light area and wait.
8. If you have been successful, before long the moss will change to baby ferns. Gradually acclimatise them to growing outside the plastic bag.

Of course some Ferns can be propagated just by laying a frond on the ground and pegging it down. Plantlets form along the mid-rib.
9. Prick out the babies, I usually do this in little groups, you can always do it again when they are bigger.

Submitted by Jeddeloh on Mon, 08/27/2012 - 21:46

I've got an even easier way of growing ferns from spore using peat pellets.  I put the pellets in a clear plastic container, drop the pellets in right side up, pour in boiling water and slap the lid on to sterilize everything.  I try to pour the water down the sides so the peat doesn't wash out of the pellets.  Once it's cool I peel the netting back from the top of the pellets and sow the spores.  The containers then go under florescent lights.

I've learned the hard way that plastic take out or produce containers don't work (but save them for step two)-they melt when the boiling water hits them.  The Container Store (America's tribute to excessive consumption) offers these handy 7-1/2" x 6-1/2" x 3-5/8" accessory storage boxes that hold nine pellets perfectly.  Trust me, you don't need any more than nine pellets worth of any one fern.  You can of course use any heat resistant clear plastic box.

I find it almost impossible to sow spore thinly enough so I usually end up having to transplant prothallia. I use the produce containers for this. After punching holes in the bottom I add up to two inches of clean potting mix and plant the prothallia or little sporlings into it.  The prothallia and sporlings can be gently teased apart and pressed into the soil.  After they are established and growing happily I start slowly removing the lid to acclimatize them to "room air".

This method seems to work to germinate any fern including dryland types.  One needs to get the dryland types onto a better drained substrate sooner rather than later, however.  Transplant those guys early. 

Tim, do you have Asplenium trichomanes 'Incisum Moule'?  If not I can get you spore.  It's a cutie.

Jan

Submitted by Tim Ingram on Tue, 08/28/2012 - 01:15

Jan - no I don't, love to try it. I grow a lot of larger ferns in the garden (especially polystichums) but am keen to try a lot more of the dryland and alpine species. It is interesting to hear about your technique, I've always sown spores as per Palustris.