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Elisabeth C. Miller Library

Keyword: Mosses

Controlling liverwort

Both my front and back gardens have become covered in moss and/or liverwort. It has intermingled with groundcovers such as sweet woodruff and blue star creeper. I have dug up the liverwort in the past but it comes back. Any suggestions towards eradicating it would be greatly appreciated.

 

It would be important to distinguish among mosses, lichens, and liverworts. Mosses and lichens are not harmful to garden plants. One species of liverwort is known to be a bit of a pest, mainly in greenhouse-grown plants. A first step would be to bring samples to a Master Gardener Clinic for identification. See the following on moss and lichen in gardens:

There are researchers at Oregon State University who have done work on the species which is prevalent in greenhouses, Marchantia polymorpha, but the following information may not be relevant if that is not what you have growing in your garden. The first thing to do–if this is indeed the liverwort you are seeing–is to make sure you are not providing the ideal conditions for liverwort growth. Note that high nitrogen and phosphorus levels encourage growth: if you use fertilizer, check the levels of these nutrients. Avoid quick-release synthetic fertilizer. Below is information on methods of greenhouse (not garden) control of liverwort, from the OSU website:

“Before talking about how to kill liverworts, let’s talk about conditions in which liverworts thrive. Liverworts grow vigorously in conditions with high humidity, high nutrient levels (especially nitrogen and phosphorus), and high soil moisture. In an environment that has any of these 3 conditions, it will be difficult to control liverworts (even when using herbicides). In order to effectively control this weed, you must make growing conditions for the liverworts as difficult as possible. To do this, you should attempt to create an environment where the ambient air is dry, the surface of the container is dry (as dry as possible), and nutrients are not available on the container surface.”

The link above discusses postemergence control, but bear in mind that if something like acetic acid is used on liverwort growing on your plants it will affect the plants as well.

The Royal Horticultural Society says that liverwort will not harm plants (except by causing competition for small plants) but its presence indicates compacted, acidic, and/or bare soil.

The only time I have encountered liverwort is when transplanting nursery-purchased plants. With these, I physically remove the liverwort from the pot before planting into the garden. I wonder if your soil drains poorly, gets too much water, and/or too much fertilizer. I hope the information above will give you some ideas. Again, I recommend getting a conclusive identification before proceeding.

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Common Mosses of Western Oregon and Washington

Common Mosses of Western Oregon and Washington cover

Common Mosses of Western Oregon and Washington provides the beginning bryologist a key to 200 species of mosses found west of the Cascades, including a few of the most common species found on both sides of the mountains. Keys for any plant group can be challenging, but the introductory section gently teaches the steps necessary for accurate identification, including the use of a microscope as an essential tool. The many close-up photographs are also a boon.

Authors Bruce McCune and Martin Hutten recognize this is just a sampling of the more common mosses of our region, expressing much respect for the 1971 comprehensive moss flora by Elva Lawton that included 598 species. “We hope that one of you using this key will eventually produce a new moss flora for the Pacific Northwest. This is one of the mossiest places in the world, and beautiful because of it.”

Published in the December 2019 Leaflet for Scholars, Volume 6 Issue 12.

controlling moss growth in garden beds

I have a small rooftop plant bed that’s full of moss. Is that an indication of sour soil, and if so, can it be sweetened with Dolomite lime?

 

Moss is often simply an indication of a shady site or compacted soil, but can also be an indicator of low soil pH (i.e., acid soil). I wouldn’t recommend adding lime without doing a soil test for pH (you can buy an inexpensive kit at most garden centers), and without considering the pH needs of the plants you have in the bed. You would not want to increase the alkalinity of the soil if your plants are acid-loving.

You may find this link about moss growing in garden beds (from Oregon State University) of interest. Here is an excerpt:

“Mosses grow in garden areas for the same reasons they grow in lawns: for example, deep shade, high acidity, poor drainage, and soil compaction. As in the lawn, mosses do not compete with other plants. Rather, they establish in bare areas where conditions are favorable (Cook and Whisler, 1994).

Mosses have not been shown to hinder the growth of garden plants or trees. Reasons for removal are generally aesthetic. But aesthetics are in the eye of the beholder, and mosses are commonly viewed as positive features in landscaping. For example, traditional oriental gardening holds distinctive roles for mosses (Japanese Garden Society of Oregon 1996; see also Encouraging Mosses). Furthermore, in some situations mosses may help reduce moisture loss and crusting on soil surfaces.”

on roof moss removal

I’d like to hear your thoughts about the safest way to
remove moss from the north side of my roof. I do
organic gardening, and I don’t want to contaminate the
soil with runoff.

 

The City of Portland had a guide to safe moss removal (formerly available online) indicating that that the most common product sold for moss removal, zinc sulfate, is a pollutant and is toxic to aquatic life. They do say that zinc strips on the roof are an alternative, but they also release zinc, and are pretreated with pesticide.


Toxic-Free Future (formerly Washington Toxics Coalition) offers several recommendations, including physical removal of the moss, landscape planning to keep the roof clear, and the aforementioned zinc strips

Oregon State University maintains a website devoted to mosses, and one page addresses the use of zinc strips as a control. Here is an excerpt:
“Zinc strips are usually considered the long-term solution to controlling mosses […] Zinc strips and galvanized flashing are apparently relatively safe and inexpensive. They effectively kill or retard the growth of mosses and fungi and appear to have effect up to 15 feet below the zinc flashing along the length of the flashing. To use: apply the rolled zinc or galvanized flashing to each side of ridge caps along the roof peaks. Place a nail down each foot of the zinc strip. With each rain zinc is released from the strip and kills the mosses below the strip. For best results remove the existing mosses prior to treatment. The active ingredient is metallic zinc.

Effectiveness: Zinc strips are considered to be effective for up to one year for most brands. The effect of galvanized flashing (example above) can persist for decades. Success rates vary with the degree of moss development and weather. Zinc strips or flashing are most effective before mosses are well developed. Physical removal of existing moss followed by installation of zinc strips or flashing is an effective long-term strategy for suppressing moss growth.

Negative Side Effects: Direct runoff from the zinc strips or flashing to surrounding vegetation, fish ponds, or water supplies should be avoided, because some contamination by zinc is likely to occur. Zinc strips should not be used with strong acids or bases.”

The PAN Pesticides Database has an entry for one type of rolled zinc strip product.

Washington Department of Ecology has a lengthy document analyzing zinc
concentrations in industrial runoff, and you can imagine that homes with
zinc strips are simply smaller contributors to this problem.

The Environmental Protection Agency lists zinc metal strips (consisting
solely of zinc metal and impurities) as minimum risk pesticides.

I think there is no easy solution, and it is a matter of deciding on a
lesser of two evils: the physical difficulties of cleaning the moss off
the roof, which is most environmentally sound, versus the relatively
small amount of pollution from using zinc strips.

growing moss indoors

Can you provide me with information on growing moss indoors? Also, do you know if Tolmiea is known for being fragrant?

 

Here is an article(now archived), “Indoor Gardening with Moss” by Robert Paul Hudson, from the Eugene Daily News. The author provides directions on maintaining a small terrarium with moss.

The web site Bizarre Stuff is another resource.
Excerpt:

Mosses can be grown in terrariums fairly easily. Collect moss from an
area where it is okay to do so and transport in plastic sandwich bags.
Sprinkle with water and seal the bag if you won’t be setting up the
terrarium right away. Use a large, clean glass jar with a tight fitting
lid. Lay it on its side in a shallow box or on a stand so that it will
not roll. Place sand and pebbles about 1/2 inch thick in the bottom of the
jar. On top of this place some of the soil from the same place where the
moss will be collected, or mix a soil of charcoal, light gravel, leaf
mold and garden soil. The soil should be level with the opening of the
jar. A little sulfur scattered on the soil will help to prevent mold from
growing. Plant the moss by pressing it into the soil. Water the
terrarium, screw the cover on, and place it in a shady place. If it seems
too wet, leave the lid off for a few hours to allow some of the water
vapor to escape. Eventually you will get the balance of water just right,
and the moss should thrive. The terrarium should sustain itself for
several weeks or months without needing additional water if the lid is
kept tightly on. If conditions are just right, the moss may eventually
send up little stalks. Some of these stalks form spores that will fall to
the soil and germinate into new plants.

The January 2007 issue of Better Homes and Gardens has an article,
“Pleasant Under Glass,” by Suzy Bales. Here is an abstract: The article
highlights the fragile beauty evoked by glass gardens or terrariums.
Everyday containers such as carafes and vases can make ideal terrariums.
Featured in the article is an antique terrarium that becomes a stage for
a miniature woodland garden. It has flowering Cape primrose,
rabbit’s-foot fern, golden club moss and black and dwarf mondo grasses.

The January 2003 issue of Sunset has an article by Kathleen Brenzel,
“Serene Greens,” on miniature indoor landscapes:
Presents ways in creating a miniature indoor landscapes. Use of copper
trays in Irish and Scotch moss; Dimension of the ceramic cache pots for
mini bog plants; Amount of water used for hyacinth floats.

Now on to Tolmiea. I consulted several reference books and online plant databases, but none mentioned fragrance as a quality for which this plant is known. This does
not necessarily mean it has no fragrance, only that it is not notable.

 

 

replacing grass with moss in the garden

Could you tell me how to replace grass with moss in the shady areas of our lawn?

 

There are a number of options for replacing the grass in the shady part
of your garden. Should you decide to cultivate moss, Oregon State University’s page (now archived) on Encouraging Mosses should be of interest.

There are two books I would recommend, Moss Gardening by George Schenk
(Timber Press, 1997), particularly the chapter on “Moss Carpets,” and How
to Get Your Lawn Off Grass by Carole Rubin (Harbour Publishing, 2002).
Rubin gives directions for preparing your site, which involve digging out
existing plants or smothering the lawn with mulches of
leaves (12 inches), bark (3 inches), or newspaper (10 sheets thick).
Schenk offers several different methods for creating a moss garden.
Briefly paraphrasing, these are:

  1. Work with nature, allowing self-sown spores of moss to take hold.
    (Prepare the site by weeding, raking, and perhaps rolling the surface
    smooth).
  2. Encourage the moss in an existing lawn by weeding out grass. You can
    plant what the author calls “weed mosses” which will spread, such as
    Atrichum, Brachythecium, Calliergonella, Mnium, Plagiothecium,
    Polytrichum, and others.
  3. Instant carpet: you can moss about 75 square feet if you have access
    to woods from which large amounts of moss can be removed legally.
  4. Plant moss sods at spaced intervals (about one foot apart) and wait
    for them to grow into a solid carpet.Choose plants that match your soil
    and site conditions.
  5. Grow a moss carpet from crumbled fragments. This is rarely done, and
    only a few kinds of moss will grow this way, including Leucobryum,
    Racomitrium, and Dicranoweisia.

In her book Big Ideas for Northwest Small Gardens, Marty Wingate
recommends Mazus reptans. It is semi-evergreen to evergreen with tiny
blue flowers from late spring through summer. It takes full sun to part
shade and is delicate looking, but takes foot traffic. It requires some
fertilizer to stay perky. Another source of ideas is the website www.stepables.com. Click on “plant info,” then
“plant search.”

Another ground cover that can take foot traffic is Leptinella gruveri
“Miniature Brass Buttons.”

encouraging moss growth in the garden

What is the best way to encourage moss to take over and cover large surface areas in a relatively short amount of time? My goal is to replace my lawn with a moss garden.

 

Here are some links to information which may be useful to you:

Primitive Plants: Bryophytes, Ferns, and Fern Allies

Moss cultivation:

Encouraging Mosses

Mad About Moss: The Simple Art of Moss Gardening

There are two books I would recommend, Moss Gardening by George Schenk (Timber Press, 1997), particularly the chapter on “Moss Carpets,” and How to Get Your Lawn Off Grass by Carole Rubin (Harbour Publishing, 2002). Rubin gives directions for preparing your site, which involve digging out existing plants or–in your case–smothering the lawn with mulches of leaves (12 inches), bark (3 inches), or newspaper (10 sheets thick). Schenk offers several different methods for creating a moss garden. Briefly paraphrasing, these are:

  1. Work with nature, allowing self-sown spores of moss to take hold. (Prepare the site by weeding, raking, and perhaps rolling the surface smooth.)
  2. Encourage the moss in an existing lawn by weeding out grass. You can plant what the author calls “weed mosses” which will spread, such as Atrichum, Brachythecium, Calliergonella, Mnium, Plagiothecium, Polytrichum, and others.
  3. Instant carpet: you can moss about 75 square feet if you have access to woods from which large amounts of moss can be removed legally.
  4. Plant moss sods at spaced intervals (about one foot apart) and wait for them to grow into a solid carpet. Choose plants that match your soil and site conditions.
  5. Grow a moss carpet from crumbled fragments. This is rarely done, and only a few kinds of moss will grow this way, including Leucobryum, Racomitrium, and Dicranoweisia.

Another approach is to change the soil pH. Sulphur should be beneficial to moss and detrimental to lawn grass. The reason for this lies in the fact that moss grows best with a soil pH of 5.0-6.0, while lawns grow best with soil pH between 6.0 and 7.0 (according to The Lawn Bible by David Mellor, 2003). Added sulphur lowers the soil pH, creating a more acidic environment.

Natural History Museum Botany Collections

The Museum’s Botany collection holds an estimated six million specimens of mosses, ferns, seed plants and slime molds from all over the world. The botanical collection spans a period from the 17th century to the present and includes a number of historically important collections.