Many bonsai can benefit from the introduction of moss and lichens–benefit in both an aesthetic and horticultural sense. Most deciduous plantings thrive with the dressings which grow extremely well beneath the shading of the trees, soil erosion is minimised, and the soil does not dry out as rapidly.
This “cooperative” relationship benefits the Elm, Boxwood, Japanese Holly, Azalea, Maple, Cypress, pines and a number of Australian natives as well. In fact any bonsai preferring a damp growing medium and requiring an element to keep the planting’s soil in place will benefit from moss covering.
The most important aspect to remember is the aesthetic element and the moss’ suitability to your bonsai planting. If it doesn’t look good, don’t use it. For example, the scale and colour of the moss dressings will influence the overall appearance of your bonsai. Frequently, some of your most beautiful mosses will be found growing in the oddest places. Moss is often found growing along the edges of shaded foot paths. However, don’t overlook the gutters around your or a neighbour’s home. Especially if you haven’t been up there cleaning them out for a couple of years.
Use a trowel to free clumps of moss from their natural settings. When collecting, maintain an appreciation for the natural environment. Remove pieces of moss and lichens from a variety of areas. By collecting in this method, you will be assured of a continuing source for your bonsai, and the natural setting will only be disrupted in a minor way.
Once you have brought the clumps of moss home, scrap the bottom of the moss or lichen so that you are removing almost all of the field soil. An old tooth brush is ideal for this activity. Leave only a thin layer of soil and then press the moss onto the top of your bonsai’s root pad. Ensure that you remove and foreign object, stones and seeds before placing the moss on your planting. You can create a “mosaic” of moss and lichens of different textures, colours, and sizes. A taller, faster growing moss might best be planted in the back of your planting, but this too is a matter of aesthetics and personal taste.
Another consideration is that the artist in you may elect to place only a few pieces of moss around your planting and not cover the entire root pad. Again, this too is a matter of aesthetic effect. If you would like to grow moss from spores start in spring, Work the spores into the surface soil on a few plantings, preferably plantings being kept in a partially shaded area. It is important to mist the spores several times per day during the first week and especially as the weather warms up.
As the moss grows, take pieces of the moss and introduce it to other plantings. The horticulturalists among us will have other methods of growing moss. Regardless of the method, the aesthetic element must be the driving force dictating the use of such dressings. In the end, if the bonsai is growing in an extremely hot and sun-filled environment, it is likely that the moss and lichens will dry to the point of becoming ugly. Shade, moisture, and temperature will all contribute to your ability to grow and maintain these dressings. The dried moss can be crumbled over the planting and will usually come back under the right conditions. Certainly, for the purposes of display and photography, the placement of moss and lichens can add an artistic element to the overall composition of the bonsai.
Source: Bonsai Workshop