Moss gardening—led by example in Japan—is becoming fashionable again. Although some lawnowners fight the invasion of moss, others encourage it. In shady areas where grass will not grow, moss can be particularly attractive. To encourage moss, these conditions are useful:
Shade. Moss does not grow well in most of North America when exposed to sunlight. The high heat of the average summer will desiccate the moss, killing it outright. It wants protection from direct sunlight.
Acidic soils. The addition of sulfur to soil will greatly assist the moss in establishing and maintaining itself. Do not use an acidification fertilizer as you would for rhododendrons, because you do not want to raise the fertility of the soil. You only want to increase the acidity.
High humidity and standing water. If moss cannot tolerate direct sunlight, it also cannot tolerate drying out. However you arrange to provide moisture—from natural sources because you live in the Northwest or from misting systems on time clocks—moss demands high moisture and humidity to thrive.
Low fertility in the soil. With high fertility levels, other plants will be prone to invading the moss area. Without fertility, moss will gather what it needs and create thick mats that eventually become self-supporting colonies.
EVERGREEN WARNING SIGNS
If you try to grow an evergreen in the shade, the first sign that it is not happy will be stretching of the branches. The second sign will be an excessive dying back of the center of the plant.
I have established moss on some parts of my gardens by following these rules. To get the initial colony going, I followed an old recipe that seems to work. I took my nursery blender (the kitchen one is likely not a good idea) and whizzed up some chunks of moss in a bit of milk. I used a paintbrush to paint the mix onto the surfaces where I wanted to establish moss. Several times a day after the painting, I sprayed a weak solution of compost tea over the area as well. This had the effect of increasing the humidity for the moss as well as providing low-level nutrients to the rock surface for the baby moss plants to use.
On another project, I simply transplanted some moss from the bush on the edge of my property to a rock I wanted to “mossify.” This rock was then kept quite damp and well shaded for several weeks until the moss started to grow on its own. I did spray it with a weak compost tea at least once a day.
I am constantly asked about plants for very steep slopes where a lawn mower cannot operate. Although perennial ground covers are an option, one of the nicest choices for a steep slope that is part of a visible landscape is to use shrubs. Lay a landscape fabric under the shrubs to control weeds and mulch with an attractive bark chip. A few minutes of weeding once or twice a summer to remove weeds that try to grow in the mulch is the only work that needs to be done on such a bed. Once the shrubs grow up, it will be an attractive, low-labor garden area.
The key to survival or propagation of moss is constant humidity and moisture. Provide that and you can grow moss darn near anywhere with any recipe. Once you dry out the starter moss, you risk losing it no matter what recipe you use.
Once moss is well established, it is a tough plant. You can walk on it as a pathway and even dry it out and it will recover quite nicely once it is provided with water. It can be difficult to establish moss on a slope unless the watering is quite mistlike. Any heavy watering will dislodge the moss spores and carry them to the bottom of the slope. Establishing moss on slopes is best done by transplanting rather than trying to establish the spores.