Growing Hardy Ferns from Spores

Table of Contents and IntroductionAfrican Violets: the Doyen of House PlantsAgapanthusAlstroemeriasAmerican SagebrushesAmerican WildflowersAndean Nymph - a pink mimulusAquilegias (Columbines)AuriculasAustralian AnnualsBellis Perennis (Daisies)Black-Eyed SusanBlue African LiliesBreeding DelphiniumsBreeding Fuchsias: Part 1: From SeedBreeding Fuchsias: Part 2: HybridisationBromeliads from SeedButterflies in Soy SauceCacti RaisingCampanulasChilean Bell FlowerChilly Treatment for Peruvian LiliesCollecting SeedConserving Annuals and BiennialsCosmosCucumbersCycads: Living FossilsCyclamen for IndoorsDahlias from SeedDamping OffErythroniumsF1 Hybrid - What Is it?F2 and Open Pollinated VarietiesFrom Obscurity to the Height of FashionGentiansGeraniumsGermination to Pricking OutGolden Impatiens - The StoryGrowing Alpines From Seed: Part 1Growing Alpines From Seed: Part 2Growing Bananas From SeedGrowing Cyclamen From SeedGrowing Eucalyptus From SeedGrowing Ferns from SporesGrowing Foxgloves From SeedGrowing Fritillarias From SeedGrowing From Seed: From Packet to SoilGrowing Hardy Ferns from SporesGrowing Hardy Geraniums From SeedGrowing Lewisias From SeedGrowing Magnolias From SeedGrowing Meconopsis From SeedGrowing Proteas and Related Genera from SeedHandling Small SeedsHardy Annuals: Part 1Hardy Annuals: Part 2Hardy CyclamenHardy SpurgesHelleboresIncreasing your Violas and ViolettasKeeping Records of Seed SowingLettuce - the Vital Part of any SaladLord Anson's PeaMagnolias - the Root of the ProblemMimulus from Seed to Seed in Sixty DaysNew Guinea ImpatiensOld-fashioned Sweet PeasOnions with EverythingPansies are not Difficult to Grow from SeedParsleyPerennials for American GardensPetuniasPhygelius - their cultivation and propagationPinks: Evocation of the PastPlants That Flower OncePrickly but NicePropagatorsRadishesRaising PalmsRaising PrimulasSalad Leaves - a lot to be desiredShow Stoppers Twice OverSowing SeedsSowing in Open GroundSowing to Feed our FriendsSturt's Desert PeaSweet Peas - Autumn SownSweet Peas - Sowing and GerminatingTall and HandsomeTechniques with Tiny SeedTexas BluebellThe Effect of Light on Germination and SeedlingsThe Nervous PeaThe Scarlet Welsh PoppyThe Search for the Yellow Sweet PeaToad LiliesTomatoesTreasure Hunt for TasteUnderstanding Latin NamesUnique Poppy (Mother of Pearl)Viability of VegetablesWeaning SeedlingsWill the Real Mimosa Please Stand Up

Ron King looks at a unique group of plants that do not have seed in the conventional sense

The purpose of this article is to encourage you to try a much neglected form of propagation: growing ferns from spores. It costs little and once you start it will send the adrenalin racing through your veins when you see the first tiny fronds developing on your very own fern. Most of the very beautiful, finely divided ferns like Athyrium filix-femina 'Plumosa Axminster' are rare and not easily obtained, so there will be many times when spore sowing may be the only answer to obtaining a particularly desirable fern for your own garden.

A considerable increase in the culture of hardy ferns has arisen amongst gardeners in recent years. It is now realised that they are a valuable asset to the garden, adding much to its interest and variety. Alpine plant enthusiasts have also discovered how satisfying it is to grow the dwarf species amongst their collection of alpine plants.

There are some 860 hardy species of hardy fern being grown in the British Isles. When a new plant arrives, it can be spread around quite rapidly by breeding from spores. For example, when that beautiful Onchium japonicum was first brought to this country from Sichuan China in 1981 it was indeed rare, but now it enjoys popularity by reason of its beauty and ease of propagation from spores, which come 100% true. If you see a beautiful fern in somebody's garden, ask permission to acquire a frond in September, when the spores are ripe, and try growing it for yourself,

When large numbers of ferns are required, the best method of reproduction is to sow spores, especially in the cases of the true species and varieties which are known to breed reasonably true. However before you decide to embark on a spore sowing exercise, I should perhaps point out that not all spores breed true to type and the following results indicate some of the unexpected plants I have raised over a period of time.

A successful sowing of spores from Athyrium filix-femina (the true species) should, on average, give you a crop of perhaps sixty ferns which will be 100% true to type. On the other hand, from a sowing of the painted lady fern, Athyrium goringianum 'Pictum' from which say 60 plants are raised, you can expect 3 which are true to type. The rest will be plain green ferns with the odd touch of red on the lower rachis (main stem) and a few with so little grey on the fronds as to be unacceptable. A sowing of spores from Athyrium filix-femina 'Plumosa Axminster' will produce ferns which are similar to the parent, but tend to depauparate at the tips of the pinnules and very few will be acceptable as being near the original clone. Offsets from the original plant is the only answer with this particular fern.

Athyrium otophorum, is a hardy fern from China, which, like the Onychium japonicum that has already been mentioned, is not only desirable, but breeds 100% true from spore, as do the rusty back fern, Ceterach officinarum, the hard fern, Bletchum spicant, and the male fern, Dryopterisfilix-mas, together with its varieties.

Collecting spores

Only perfectly symmetrical parents should be chosen as a source for spores as there is a tendency for irregularities and deformities, such as constant irregular pinnae and tendencies to revert, to be transmitted to the offspring. September and October is the time when most spore ripen, with the polypodiums ripening later in November or December.

If you are not familiar with spores, look on the back of a fern frond and, depending on the type of fern, you will see elongated brown growths or perfectly circular ones, which are the spore capsules, or sori, in which are contained the spores. When ripe the spores are ejected into the air by a spring mechanism inside the sorus called the sporangium. If you tap a frond with your hand whilst holding a sheet of white paper under it, you will see, if the spores are ripe, what looks like brown rust appearing on the paper's surface. These are the spores, which individually are invisible except under a microscope.

A fully grown plant of the lady, male or soft-shield fern can produce over a thousand million spore in one season, although few will find conditions suitable to germinate and reproduce.

To collect the spore, detach a frond from your chosen plant and place it between two sheets of newspaper, folding along the edges to contain the fine spores as they are released. Lay the newspaper flat in an airing cupboard or on a very sunny window-sill, both of which will ensure that the frond dries quickly to prevent mould forming.

Germinating the spore

Just four pieces of equipment are needed: one 6inch half-depth, plastic pot and a saucer in which it can stand, a plant label, a plastic bag of about 9 x 15in. and a small amount of a Soil-less compost.

Fill the pot with compost, firming the surface with the base of another pot or something similar. Place a circle of newspaper over the surface of the compost and pour a kettle of boiling water over it, so the compost is sterilised. When the content of the pot is barely warm remove the paper (there to ensure that the compost is not contaminated while it is cooling) and thinly sow the spores over the surface of the compost. Do not cover them with compost as one would with seed.

Place a suitably annotated, sterilised label into the edge of the pot and put the whole into the polythene bag, tucking any surplus under the pot to form an airtight seal. Place this on a saucer in the house on a north-facing window-sill. Do not remove the plastic bag for any reason for six months. After a period of about one month, the surface of the compost will have turned green; this is the germinating spores and the beginnings of the prothallus.

The prothallus

For those of you who are not familiar with the life cycle of a fern, the spores on germination do not produce a young fern, but something which is an entirely different plant. This is a small scale-like organism, called the prothallus, which is the bearer of the fern's sexual organs. Fertilisation takes place in the moist atmosphere and from the prothallus there grows a young fern similar to the original parent. The prothalus is quite small and not easy to see until it has grown to about 3/8in. (1cm) across, when it can be seen to be heart-shaped.

If the spore is sown in September, then by December the prothallus should have developed and by March the tiny fern fronds should be in abundance.

Pricking out

Do not try to prick them out at this stage as they are far too delicate; instead get a plastic seed tray 2in. (5cm) would be ideal, and fill it with a soil-less compost. Firm the surface and dig out a series of spoon-shaped depressions with a tea spoon. Take the pot of young ferns and dig out similar spoon shaped groups of tiny ferns and place them in the corresponding depressions in the tray. Stand the seed tray in a bowl of water and soak the compost thoroughly from the bottom through the drainage holes. Drain and cover the seed tray with a plastic propagator top and then return it to the window-sill until May. This first division of the tiny ferns is essential to avoid overcrowding and to enable them to grow without becoming too tall and leggy.

In May the propagator and seed tray can be removed to the greenhouse or cold frame, where it should be placed out of direct sunlight and in a cool position.

Come September the ferns will be robust enough to be divided into single plants, when they can be potted up into 3Oin. plastic pots. At this stage feed can be beneficial and a weekly dose of Phostrogen is recommended. As soon as roots can be seen growing out of the bottom of the pot, repot immediately into a 5in. or 1 litre pot. It is important that growth is not retarded, nor should there be any restriction to the very large fibrous root system that is common to all ferns. I would suggest that for the first winter, ferns are left in their pots and not planted outside until the following spring, bearing in mind that once they are outside they are in direct competition with other plants.

Growing ferns from spore is not too challenging, but the excitement of seeing the first miniature fronds is very difficult to beat.