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Propagation
The majority of the plant propagation done at the nursery is through spore cultivation. This may sound very scientific but in fact it is fairly simple, however it is quite a lengthy process from start to finish. Taking 2-3 years for small plants to be produced. The two main advantages of spore propagation are; firstly it allows us to propagate the ferns we want many of which may not be widely available; and secondly we can cross ferns to produce new species, making some of the ferns in our nursery unique!
Propagating ferns from spores is easy, try it for yourself!
Step 1. The first step is to collect your spores; this is best done in mid summer (July-August in the UK). The spores can be found on the underside of mature fronds or fertile fronds. If you are unsure try a few different fronds from around the plant. It doesn't hurt established ferns to remove fronds although it may ruin the appearance of the fern so ask before ripping apart your neighbour’s prize plant. Spores are usually ripe when they turn a deep brown/black colour, often ripe and unripe spores can be found on the same frond as they ripen in sequence from the tip to the base. We often take several pinna from different parts of the same frond to ensure ripe spores have been collected. Once the spores have been collect we place them in clearly labeled envelopes and place them in the airing cupboard for 3-5 days to allow the spores to shed.
Ripe sori on the underside of Microsorum diversifolium
Step 2. The next stage is to prepare the compost, at least 24 hours in advance of sowing. At the nursery we use both propagation trays and plant pots; anything that can be sealed to keep moisture in e.g. drinks bottles, plastic food containers. Once you have selected your container make sure it is clean as dirt may carry other plant seeds. Fill your container with soil; it is good to experiment with soils to see which work best for you. Most commonly used are ericaceous compost, peat and sand. We often experiment with different mixtures and also straight garden soil, houseplant compost anything you can your hands on! Once you have filled your container the compost needs to be sterilized, the easiest way to this is to pour boiling water over the entire surface of the compost ensure all compost has been scalded. This process kills of any competing seeds from germinating. In totally sealed containers try to minimize the water used to scald as the compost wants to be damp not water logged for planting. Once the surface has been scaled either seal or for flower pots place into a re-sealable freezer bag and allow to cool overnight.
Step 3. Now the spores have been collected and the compost has been prepared, sowing can take place. It is best to do this in a still environment and to change locations between sowings of different spores, otherwise cross contamination can occur, but this may also create exciting new ferns!
One of the advantages of using an envelope to dry the spores in, is it can also be used to clean the spores (although this process is not essential). Tap the spores into one corner of the envelope and tear the corner off.
This will create a funnel to pore the spores down. Angle the funnel at 45° and gently tap the bottom, you will see the brown debris fall off, leaving behind a very fine layer of brown dust, these are the spores!
Step 4. Once the spores have been cleaned they are ready to sow. I cannot emphasize how important it is to sow the spores thinly. The more spores you sow the more competition there is, thus the plants will crowd themselves out and growth will be stunted with many prothalus dieing (first stage of growth). Once the spores have been sown label them all clearly to avoid confusion when planting on. Then leave the sowing's in good light but not direct light, they can be left untouched for 9-12 months. If spores are sown midsummer a green film may appear on the top of the compost after 2-3 months. With some spores such as Dryopteris felix-mas and Polystichum setiferum congestum a green film may appear after just a few weeks! For some spores it may take much longer up to a year for the first signs of life to appear so be patient. There is no need to water them as the sealed bag/container will not lose water.
Step 5. Once several true fronds have appeared over majority of the pots surface, the plants can be hardened off. It is important to harden off the young plant gently as the sudden change from the high humidity environment to a dry atmosphere can kill the young plants. To avoid this leave the container or plastic bag open and slowly over a week expose them completely. The young plants can now be pricked out. There is always the urge to plant on all the young plants, but unless they are very rare or you have very few only plant on the strongest otherwise you will amass a large quantity of weak plants. We plant our young plants out into plugs in a sandy-ericaceous mix this encourages good root growth and helps prevent the plants from rooting if they get to wet. After about a year or growing season the plants can be potted on, we tend to pot into 7cm pots at this stage.
The finished Product!
We find this method to be very successful, but it is only a guide so don't be afraid to experiment with the method, and if you have any problems or have any suggestions please contact us!
