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Cultivation  of Ferns

How to grow ferns is a tricky proposition indeed.  There are various methods of growing ferns, however ultimately the only person who knows what's best for your ferns is you.

When trying to start a fern collection, keep several things in mind.  First, ferns generally require some shade.  There are only a few species that will tolerate full sun.  In order to look their best they should be grown in dappled lighting.  Second, be sure that your ferns will be able to be watered at least once a week, no matter where you decide to put them.  Whether growing 
them in slat baskets, wire baskets, plastic pots, terracotta pots or planted in the ground, they 
will require a regular schedule of  watering.  Occasional applications of a fertilizer to your 
ferns enhances vigor and growth.  Any commercial fertilizer will do just fine.  Peterís 20-20-20, 
is an excellent all purpose fertilizer.  As you grow more ferns, then you can experiment with different types of fertilizers.  One that is particularly effective is Fish Emulsion.  However, this particular fertilizer, while highly effective tends to smell like, well, dead fish!!!  Many fern 
growers also use time release fertilizers such as Osmocote or Nutricote, this way bypassing 
the need to apply fertilizers every two weeks.

These are general rules in trying to keep ferns alive.  Another important ingredient is humidity--particularly for tropical ferns.  These ferns rely on humidity probably more than anything else to sustain them.  If you are growing tropical ferns, they will generally tend to 
want to be outside plants rather than inside plants.  However, there are exceptions.  Many 
of the Boston Ferns, Nephrolepis, will do very well inside and with less humidity.  Many of 
the cultivars of this group, particularly the fine leafed Boston Ferns, prefer a less humid and 
more exposed situation.

Asplenium nidus, one of the bird's best ferns also will do well indoors.  In South Florida, we humans prefer to have our air conditioners turned on from March to November, and 
subsequently, some ferns  will suffer if left indoors for extended periods without humidity.

If you are planning to keep ferns in the house, it is a good idea to make sure that they are in brightly lit situations, but out of direct sunlight.  For small potted plants, keeping them on a water-filled saucer with the pot resting on pebbles will keep humidity near the fern.

Some growers like to keep their ferns in a bathroom, or near in a kitchen window near the 
sink so that they may take advantage of the moisture in the air.

Propagating ferns 


Ferns can  be propagated by various methods.  One of the easiest ways to get extra plants is through divisions.  However, not all ferns are amenable to this method.  Many of the Nephrolepis group can be divided easily.  Many of the Adiantums, also are easily divided.  However, care should be exercised when there is a single rhizome stock on the plant.  

Another way of obtaining plants is through bulbils or babies on the mother plant itself.  There are groups of ferns such as Diplaziums, Aspleniums, Tectarias, and a new subgroup of Tectarias:  Pleocnemia and Heterogonium that produce offshoots on the fronds.  These latter genera are represented in cultivation by Pleocnemia irregularis and Heterogonium pinnatum.

A definite way of propagating, though time-consuming is by way of spores.  Since all ferns produce spores, this method is most promising.  However, growing from spores requires patience.

There are a number of methods used by a number of people.  What works for me is outlined here.

The first step in propagating from spores is to select viable spores.  This is best done by removing a frond that has mature spores.  This is best done by observing how the sori look.  If they are plump, it is a good bet that the spores are ready to dehisce.  In looking for good spores, you will find, depending on the genus, that the color of spores varies greatly.  In many Polypodium species, they are yellow.  In Bolbitis, they appear black.  There are some green spores, usually found in plants such as Platycerium wallichii, and capturing them is very tricky.  But generally, removing a frond from a plant and putting it on a  sheet of paper out of a draught should yield good spores.

Spores need a germinating media, I prefer a commercial brand (Fafard 3B).  I sterilize my media in a bowl in the microwave oven for a couple of minutes.  (Sterilizing the media too long renders the mix useless.)  After the mix has cooled down, I put the mix in small plastic containers that have good fitting lids. I use tap water (I have used rain water, and purified water, but I am not sure of a positive effect) to wet down the mix and distribute my spores).

To go back a bit, once the spores have dehisced (shed) there will be considerable debris on the paper.  The majority of what you see are shed sporangia--the spores were inside of these cases.  Now you must separate the sporangia from the spores which are considerably lighter and definitely smaller.  By tapping the paper, you can separate the two.  The sporangia, because of sheer weight, will move, thus leaving the spores behind.

Once you have the spores separated, it is easier to hold the paper above a container with the sterilized mix and gently blow the spores onto the dampened media.  One of the greatest problems in sowing spores is to make sure they aren't sown to thick.  Once the spores are sown, cover the containers and wait.  The container should be put in an area of good light.  I use artificial lights to grow. If you have sown the spores successfully, there will be gametophytes within 4 weeks.  As these grow it is not immediately necessary to water them.  Because of the sealed container, the plantlets are living in a 'terrarium' and at this stage need no extra attention. 

As the gametophytes change into sporophytes, it will be necessary to separate the small plants in order to give them room to grow.  You should try using the same type of media when transplanting sporelings.  Try not to keep them out of the containers too long because they will dehydrate.

The sporelings will now take several months to grow and eventually they can be removed from the containers, however this has to happen over several weeks.  The sporelings have been growing in an environment of 100% humidity and they must now face the outside world with less than perfect ambiance.  It is possible to remove the lids slightly over a two week period.  During this time, you probably will have to occasionally mist the sporelings. 

This process is called 'hardening off" the plants.  After you believe that the sporelings are thoroughly acclimated, pot them up as usual.