Moss is a simple type of plant that lacks roots; the plant is anchored by means of threadlike structures called rhizoids. It also lacks stems, and leaves. The name Moss refers to any species of the class Bryopsida that is part of the division Bryophyta. Bryophyta means the first green land plants to develop during the known evolutionary process. Moss is thought to have evolved from very primitive vascular plants. Moss is not known to have given rise to any other kind of plant, an evolutionary dead end of sorts.
Because moss lacks traditional vascular structures of true leaves, stems, and roots, its growth is limited to moist locations, since their cells must absorb water directly from the air or the ground, moist locations suit them well. Moss also absorbs the nutrients it needs from the air, not from the ground as most plants do. An interesting side note to consider is that without water, fertilization cannot occur in mosses.
Moss grows almost everywhere, except under the sea. Except for Sphagnum peat moss, moss is generally of little use to humans with the exception of bonsai for soil covering and in gardening. The Japanese have been gardening with moss for many years and Moss Gardening is slowly catching on in other countries. Moss is also of little use to animals, although it is sometimes eaten in times of famine.
Other plants that are not related to moss can share the name moss. This includes club moss, flowering moss, carrageen, reindeer moss, and Spanish moss. The Japanese have gardened with moss for centuries. Valued for its reduced need for watering and its greenness, it is considered to add a feeling of lushness and serenity to Japanese gardens.
We as bonsaists use moss to add a dimension to our bonsai that helps with the overall visual illusion. We put it on to the soil surface to give the illusion of grass, plants, and such growing in scale under the tree. A little known fact about moss is that mosses leech minerals into the soil when watered. This benefit however is often negated by the fact that moss, if allowed, will make a shield on the surface that water will not penetrate. It can also create a barrier, trapping in moisture and not allowing the soil to dry out. This is the reason that most people will recommend that moss only be applied to the surface of the soil a few weeks before showing the bonsai and removed immediately afterward.
Moss can be left on your soil year around if some simple precautions are taken. Always leave spaces between the pieces to allow for water penetration and evaporation, never butt up the pieces tightly. A good rule is to cover no more than 75% of the soil surface with moss. Try also not to run the moss right up to the pots edge, leaving the rim area free, ending the moss naturally at this point will give a better illusion.
Be careful with pines and most conifers, as most are dry loving trees. If your moss on these is green and healthy, chances are that you are watering too much. I have had some success keeping healthy moss on a Scots Pine by watering as normal but also lightly misting the moss on a daily basis. Vance Wood keeps his “Silver Moss” growing on the soil of his award winning Mugho Pines year around. Mugho’s do like a little wetter soil than most pines, which could be the reason for his success.
Many people simply collect whatever moss is handy when they need to add it on the soil surface or their bonsai and this works perfectly well, I often do this myself. However, if one wishes to have different colors and textures available then cultivation is the easiest way to achieve this.
By cultivating moss, a person has many different mosses at hand at all times and the opportunity to mix textures such as a fine green moss mixed with some feather moss to represent ferns can add greatly to the overall presentation. Mixing other textures and colors together can create a more natural looking presentation and there is room for so much creativity in this area that it is basically a blank unused canvas by many bonsaists.
I use two different techniques for cultivating moss, which I will call the “paste” and the “tray” techniques. The paste technique is my preferred method and the one I use the most often. When there is not enough moss to use this technique with, as in the case of a small piece of Vance Wood’s silver moss I acquired, I will use the tray technique.
For the purposes of this article I will do both techniques side by side so you can get an idea of the differences.
When I collect moss, I place it in a sunny spot and let it dry out some, not completely but enough to be easy to crumble and cut.
Cultivation in Trays
I take a shallow container with small drainage holes and put an inch of fines or sand into the bottom and mist it until it is damp. I then take my moss and mince it very fine with a razor blade and then sprinkle it evenly on the surface of the sand or fines. I then mist again and put in a dappled shade spot being sure that the top never completely dries out. It will usually require misting once a day. In two weeks time the entire surface will be green and shortly there after you will have a perfect sheet of moss. I have grown the moss in its original container for over a year and it is a handy way to keep moss ready. The main draw back is that the sheet is always somewhat uneven, which if you are using pieces when applying, is not a big problem.
Cultivation on Bricks or Blocks
This is a method that I have been very successful with in the past. I collect moss and let dry slightly outside in the sun. I then use a blender dedicated to this use only and add beer (some people use butter milk or water) and blend until I have a paste with the consistency of mortar. I then place a brick into a tray without drainage holes and fill the container with water; the brick acts like a wick constantly drawing water up. I spread the paste on top of the brick and mist daily, in a few weeks the moss will begin to grow on the brick and eventually will create a solid carpet of moss. This technique will allow you to take perfect sheets off of the brick easily, whenever you need them. Larger sized patio blocks can be used for bigger sheets.
The paste can also be used on your rocks in your shade garden; the moss will grow as long as it is keep moist. I have seen garden benches, walls, and statues covered and decorated with moss using this technique. A few creative individuals have even used this paste to spell out messages on block or brick walls.
Below is a picture series of the steps taken to cultivate moss in the manners described.
Typically the moss grown with the traying technique will be actively growing in just a couple weeks and ready to use in three to four. Once there, however, it can be kept for use and cultivation stock for quite a long time provided it is not allowed to dry out completely.
The same applies to the pasting technique.
When collecting moss to cultivate or transplant, you’ll want to look in bright sunny places as it is very difficult to cultivate moss that has spent its life in shady areas in the sunny confines of a bonsai pot.
When picking out moss to cultivate or transplant, keep in mind the texture, color, shape, depth, and feel of the moss. This is the moss that will eventually end up on your bonsai soil, so keep appearance in mind. You will also want to collect more than one species of moss as it more appealing to have different types, colors, and textures planted together in you bonsai. A technique I use in forest plantings is to use a darker colored moss directly under the trees, inside the forest and to use a lighter shade of moss outside of the forest. This gives a fantastic illusion of shading and shadows.
Rooftops, sidewalk cracks, patios, and open sunny field are all excellent areas for collecting.
Transplanting moss is easy if care is taken to assure that it takes to its new environment. Large pieces are far more easier to work with than smaller pieces, so look for a source that is growing in full sunlight as these types are more readily able to adapt to the sun a bonsai receives.
Using that flat end on your soil rake or another flat object such as a butter knife, carefully lift the moss up, taking care to get large, unbroken pieces, and place it into a plastic bag to maintain it’s moisture and to prevent damage. It is wise to scrape off as much soil from the bottom of the pieces as possible so as not to get dirt on the other pieces in the bag and it will need to be removed eventually as we do not want that soil in our bonsai mix.
These pieces will stay alive and fresh for a very long time in the plastic bag if they are not allowed to dry out.
If moss is being collected to use for “seedling” stock then small pieces are perfectly fine and no care need be taken to prevent it from drying out. However, as much soil as possible should still be removed from the underside as this is useless for any purpose and since moss does not have roots, so to speak, no harm will come of this practice.
Applying moss to a bonsai can be called an art form in itself as the arrangement, spacing, texture and color can either greatly enhance the visual appearance of the overall presentation or sadly, take from it.
For the health of the tree one should follow a few guidelines when applying moss.
- Never cover more than 75% of the soil surface with moss. This is to assure good drainage, evaporation, air transfer, fertilization, and it also gives a natural appearance to the whole presentation.
- Leave spaces between the moss pieces that you apply for all of the above reasons and to allow room for growth without the moss “mounding” to high.
- Besides the spaces between moss pieces, leave a space around the rim of the pot that is moss free. This gives an impression of a framed picture in which the image does not disappear out of the frame. With this space and the spaces between the pieces, it is quite easy to leave 25% or more of the soil surface moss free.
- Although by leaving 25% of the soil surface free greatly reduces the tendency of moss to impede drainage and evaporation, thereby creating a constantly wet environment for the roots, care should still be taken when moss is left on a bonsai year around. Many artists apply moss a short time before showing it and then remove it afterward to prevent any problems and some trees such as the dry loving pines are difficult to keep moss on because if the moss is healthy, chances are the soil is too wet for the tree.
The key to successful application and continued health of moss onto your bonsai soil is the soil itself. Preparation is the key and this means preparing your particular soil mixture to allow for not only continued drainage and air exchange, but also to give a good smooth base for the moss to grow on.
First, using a towel (usually on the other end of your soil rake) or a similar tool smooth and arrange your existing soil, leveling or mounding, while removing about a half inch of the existing soil to allow room for the moss and soil for it.
Once you have removed some soil and arranged it into the shape and level you want it is time to spread a very thin surface coating of fines onto your existing soil surface. Doing this makes a level, smooth surface that the moss can easily adhere to while creating a thin water retention area for the moss. I save my fines from sifting my soil ingredients for this purpose, for moss I use a mix of 75% turface fines and 25% pine bark fines.
Let me explain what I mean by a thin layer. Look at your soil mix before applying the fines mix, you will see slight irregularities when the particles touch. There will be dips and crevices as in the illustration below. The fines are used sparingly and only to level the existing soil mix.
Once the fines have been applied to the soil surface then moss can be applied. I’ll use an example of a single bonsai for explanation purposes, although the same techniques apply to any style of planting, the textures and color of the moss used may change and is completely dependant on the desire and vision of the artist.
Place two piles of moss on which all the soil possible has been scraped from the bottom and the moss has been flattened out as much as possible. One pile is of a light colored moss with a fine texture, the other pile is of a darker moss with the same texture. Also have a small container of the same fines you used to level the soil, a trowel, a piece of notebook paper, a pair of scissors, and a misting bottle.
Mist the soil surface until it is damp to allow the moss to be seated properly once it is applied.
Starting at the base of the trunk, use the darker colored moss first and tear (cutting does not look natural) pieces roughly a couple of inches in diameter, some more, some less, depending on the overall image you have in mind. Then use the scissors to cut an angle of about 45 degrees at the edges of the moss angeling in toward the center.
Using your fingers to tear the moss, if necessary, to fit around the trunk or exposed nebari, place the darker colored moss onto the soil surface, leaving about a 1/8 inch gap between the pieces. The darker colored moss is meant to represent shade from the foliage above, so when placing it, keep in mind the angle of your imaginary sun and roughly follow the outline of the shade that would fall naturally. continue this placement of the dark moss, ending in an irregular outline somewhere near the drip line of the tree, or on one side if you want the shadow to be cast to the left or right.
When placing the moss, avoid any look of controlled regularity, be random.
Next take the lighter colored moss and continue from the edges of the darker moss out to about 1/8 or 1/4 of an inch from the pot rim.
Once the moss is applied use the trowel and press it firmly into place, the misting of the soil earlier will allow the moss to seat well. Press the edges firmly down as well as the center of the pieces.
Now take the piece of notebook paper and roll it into a funnel with a tip that is just big enough to let the fines pour through slowly. Keeping the small tip closed, pour some fines into the big end. Now release the fines into the spaces you left between the pieces and at the pot edge using the funnel to assure that only the spaces are filled up to the level of the moss and not over it.
Give the moss a good misting, wetting the fines completely and use the trowel to press the moss and the fines down again firmly. Fill any spaces that need it and using tweezers, pluck any fines that spilled off of the surface of the soil.
If done properly, the technique above will give the illusion of a tree surround by grass that shades the grass underneath while the grass outside of it’s shadow is hit by the sun.
It should be mentioned that a single color of moss can be used and often is, the same techniques for application apply. You can also mix textures as well as colors, let your imagination rule.
I hope I furthered your understanding slightly on the way moss grows and survives in a bonsai pot as well as how to cultivate it successfully. Hopefully I also opened up some considerations for you as to the many ways in which moss can be used to enhance the wonderful illusions we create with our bonsai.