Moss is a primitive plant with tiny leaves that are generally only one cell thick. Some mosses are velvety cushions, some are like small forests, other are branching and spreading. Though many gardeners dislike moss in their flowerbeds, it can be an attractive and effective ground cover. One moss look-alike, liverwort, may be more damaging to the health of your flowers than the true mosses.
Mosses are low, soft plants usually no more than 3 or 4 inches high, often much less. Botanically, they are called Bryophytes and are characterized by bearing spores in capsules that sprout to form a felt-like body called a protonema. This, in turn, sprouts the moss plant that typically has stems and leaves and root-like rhizoids, or holdfasts.
Mosses absorb water through their thin leaves, needing nothing from the soil, rock or wood they grow on. Though most abundant in high rainfall areas and on acidic soil, mosses are found growing in high deserts, immersed in mountain streams and attached to alkaline concrete. Many species require very specific conditions to grow well.
Effects of Moss on Flowerbeds
Since they need nothing from the soil, moss does not compete with flowers or other plants. Very tiny mosses may coexist with rock garden plants or other miniatures, but most moss will grow taller than the plants and crowd or shade them out. Larger plants, however, may benefit from the moss as a living mulch, cooling and protecting the soil from drying out.
Moss in a flower garden may be a sign of acidic soil, however, and some plants that prefer neutral soil, pansies for example, may do poorly because of the low pH, not because of the moss.
Adding Moss to Your Garden
One of the easiest ways to get moss to use as living mulch is to rake it out of your lawn. The moss that grows in lawns is often able to grow without anchoring itself into the ground by rhizoids. This allows you to spread it out in a thick layer and, later, pick up the blanket of moss and pull it outward to cover a larger area or transfer it to another bed. Any weeds growing through the layer of moss will be pulled up by the roots and will die without further effort needed.
Another method is to transplant pieces of naturally occurring moss into your garden from a natural area. Always get permission from a landowner before doing this, or find out what regulations cover the collection of moss in parks and open land. Water your transplants frequently until they get established.
Some moss will start from pieces mixed in a blender with an acid substance like buttermilk. This is worth trying, but be aware that many mosses cannot be propagated like this.
There are companies that sell moss by mail order, but you may have better luck with species that occur naturally in your area.
If you prefer not to have moss among your flowers, remove it by hand, or try to create conditions unfavorable to its growth. Adding lime to the soil to raise the pH may help, though be sure that your plants also prefer a higher pH. Let the soil dry out between waterings and remove excess foliage to allow sun to reach the ground. A dry coarse mulch of bark or straw will also discourage moss.
Liverwort and its Control
While moss can coexist quite well with most larger plants, liverwort seems to discourage the growth of many flowers and small shrubs. It often grows with moss and looks like small flat green leaves pressed against the ground. It has become a pest in many greenhouses, covering the top of the soil in pots and shunting water and fertilizer off to the side of the pot.
At home, in small areas, removal by hand is your best bet, followed by application of a mulch that dries quickly such as hazelnut shells or coarse bark. Allowing the top of the soil to dry out regularly helps in control also.