Fernes, Mosses and Liverworts (Ground cover for bonsai)

The ground cover of your bonsai is one of the important aesthetic elements that will improve the overall visual composition of your bonsai, as well as assist in providing soil chemical stability and retaining temperature and moisture for the bonsai tree’s surface roots. A good choice of ground cover vegetation coupled with other landscaping accessories will complement your bonsai tree greatly. (It is also one of the assessment factors in bonsai competitions.)

There are functions for everything in bonsai, and mosses and lichens, used as ground covers, are no exception. They, of course, look great, covering the soil surface with 'green velvet' and helping to retain water while holding the soil in the container. For people buying bonsai, the presence of moss is always a good sign. There are a great number of types of mosses and lichens and these can be mixed to provide a very effective result overall. When not used for 'conservation' purposes, they should be planted sparingly so that their effect is natural, and they do not prevent water from reaching the soil.

There is a particular method of mossing a potted bonsai that will produce a smooth mat of deep green, with none of the lumpy growth that can be typical of piecing bits of moss together. With a sharp knife, slice the moss from its growing place, taking as little soil as possible. Put this moss in a container lined with paper, and moisten it lightly (it should be moist, not wet). Remove most of the remaining soil from the moss using sharp scissors, pulling each little tuft away from the larger piece.

Prepare the surface soil in the bonsai pot by scratching it to roughen it up. With long handed tweezers, start inserting each tuft of moss close to, but not against, the trunk. Work out and away from the trunk until you have the look you want, then brush off most of the tufts. Sprinkle dry soil over the moss and press it down with a flat spatula or small trowel (even your hand if you are careful). Mist gently two or three times and the soil will settle down between the tufts.

As an alternative to collecting moss and going through this somewhat time consuming process, you can use dried moss. Gather it, then place it in the shade for a few days until it is completely dry. Put it through a fine strainer - a sieve will do - to crumble it. Mix the particles with some soil and spread it over the bonsai soil in the pot, making a thin, even layer. Press it down with a flat spatula or small trowel and gently mist continually until the soft green moss begins to grow. Some people just scrape soil off the bottom of the moss and put this on the soil of the bonsai, but takes a much longer time to root and is a delight for small birds when looking for worms if left exposed. Along with the growth of a healthy crop of moss often comes the appearance of a silver fungus around the soil line at the trunk of the tree. This is a sign of a healthily growing bonsai. The fungus develops as the moss takes hold, and it cannot be artificially implanted. In the heat of summer, moss may turn brown. It means the bonsai is getting the water it needs. As soon as cooler temperatures and higher humidity return, so will the 'green velvet'.

  

Ferns, Mosses and Liverworts are flowerless plants, reproducing by small, dust-like spores that are dispersed by the wind.  They are most abundant in damp habitats and most climates, as their thin leaves are easily damaged by desiccation.  Also, unlike flowering plants that produce pollen, fertilization is brought about by a male sperm, which needs a film of water in which to swim to the egg.

Moses and liverworts belong to a group of plants known as the Bryophyta . Their spores develop in a capsule, usually situated at the top of a stalk, or seta.  Mosses differ from liverworts in the structure of the spore capsule and the arrangement of their leaves.  About 65 different mosses and liverworts have been found growing on the bark of oaks, but very few ferns habitually grow on the trees themselves.

Ferns like bright diffused light and moist soil. Prune dead fronds from the plant immediately and keep humidity near the plant high for best results.

 

 

Polypodium vulgare: Ferns are common in oakwoods but the Common Polypody is the only species that regularly grows on trees themselves.  The spores develop in the microscopic sacs called sporangia, which are arranged in orange-brown clusters, called Sori, on the undersides of the fronds.

Lophocolea bidentata/heterophylla: The bidentata is a common leafy liverwort, found on decaying logs and among mosses on woodland banks. The heterophylla grows on the lower parts of trunks and branches, and its upper leaves are unlobed, unlike the bidentata.

Isothecium myosuroides:  This is a very common moss throughout Britain and central Europe, typically growing on the lower parts of tree trunks, on falled logs, and also on shaded rocks adn boulders.  It is a pleurocarpous moss, with spore capsules growing from the sides rather than the ends of the branches, and has a characteristic olive-green sheen.

Amblystegium serpens:  This is one of the smallest European species of pleurocarpous moss, with tiny leaves, and it is common on fallen logs and the lower branches of trees throughout Britain and central Europe. It produces capsules almost all year round.

Dicranoweisia cirrata:  This is the most common of the acrocarpous mosses, (mosses that have capsules at the tips of erect shoots), of tree trunks and lower branches.  It is usually fertile and is found throughout Europe, specially in areas with low levels of atmospheric pollution.

Ulota crispa:  This occurs in small, yellow-green tufts on twigs and small branches of hazel and elder, as well as young oaks.  Widespread throughout Europe, it is less common in the Midlands and southeast regions of Britain. 

Mnimum hornum: This is one of the most common European woodland mosses.  It grows on tree trunks, decaying logs, stream banks, and woodland floors, especially on acid soil throughout Britain and central Europe. It forms extensive dark-green patches.

Eurhynchium praelongun: A delicate species of pleurocarpous moss common in central Europe, it favours decaying stumps and logs.  It has fine, feathery branches and small leaves, and regular branching of shoots is characteristic.

Frullania dilatata:  A small, leafy liverwort, it can frequently be found growing on the lower branches and trunks of oaks and other trees.  The reddish-brown colour is characteristic of the Frullania species.  It is widespread in Britain and Europe, except in polluted areas and the extreme north.

Dicranum scoparium:  This is a common moss on fallen logs, woodland banks and the trunks and lower branches of trees.  It grows in bright green patches and the tips of its erect shoots all curve over in the same direction.

Hypnum cupressiforme:  A very common moss throughout Europe, this grows in mats on banks, trees and decaying logs, Similar to isothecium myosuroides, it grows higher up on trees and has more curves leaves.

Brachythecium rutabulum:  This is a robust species of pleurocarpous moss wit a characteristic yellow-green, glossy tinge to the branch tips.  It is common on tree trunks and decaying logs, especially where the soil is fertile.  It is abundant throughout central Europe.

There exists a multitude of suitable ground cover plants for growing bonsai, and those above are only a fraction of the plentiful choices available. It must be remembered that the ground cover should never be totally shaded and covered up with growth, as the soil needs the warmth from the sun to provide conducive conditions for root growth.

Thanks Richard Lewington.