Where does moss grow

What’s the Deal with Moss?

Moss is a plant that can grow in conditions that other plants, including grasses, can’t endure. It is not a very aggressive or competitive plant, but nature seems to use it more as a filler, for thin or bare soils. So, when you ask the question “Why is there moss in my lawn?” the simple and correct answer is “because you have conditions that are making it too hard for your lawn to survive.”

Moss spores are in the air and only need moisture to germinate and mature. Once established, moss can be very drought tolerant. Some mosses can survive in full sun, though most prefer shade. Moss can grow on any type of soil because their shallow roots simply hold the moss there without drawing nutrients from the soil. They get some nutrients from water, but mostly they make their own food through photosynthesis.

The biggest myth about moss

Ask most gardeners what can be done about moss and they will tell you that that the soil is too acidic (low pH) and it needs to be sweetened with lime (calcium). This is false! As we said above, moss grows in any type of soil – acidic, alkaline, and sometimes on pure rock. The only reason that lime sometimes helps lawns squeeze out moss is when the soil actually is too acidic for the grass to grow properly and it is thinning out. Adding lime in this case, would raise the pH and improve the health of the grass. So, as you can see, the real cause of the moss here is the poor health of the grass.

Weak Grass/Moss Causing Conditions

Here are the major reasons for moss on lawns:

  1. Too much moisture. Soggy soils, often clay types, drown grass roots but shallow rooted moss can tolerate and thrive in wet soils.
    You can improve soil drainage with Aerify Plus.
  2. Too much shade. Grass plants needs a fair amount of sunlight for enough photosynthesis to keep them healthy. Shade tolerant varieties can withstand a little less light, but some moss varieties survive in total shade.
    Trimming back the lower branches of trees can be helpful.
  3. Clay soil/compaction. Grasses are tough plants that can grow in fairly heavy clay top soils, especially if the soil is moist. But extreme compaction or denser clays are almost impregnable. Moss has no problem growing on this dense clay.
    The best product for improving clay soil and compaction is Aerify Plus.
  4. Drought/ Dry soil. This might sound counter-intuitive, since moss likes moisture, but here is what can happen. When high clay content soils dry out during a drought or normal summer conditions, the loss of moisture causes the soil to actually shrink, which turns it tighter and denser. This can tear and damage grass roots and make it impossible for them to get to the nutrients and water. When the lawn finally begins to receive rain or water, opportunistic moss spores germinate easily, since the grass is not healthy enough to compete. Last summer we experienced a major drought in the North East, and this spring we are finding more moss than ever before.
    Check out our blog post on How to Water Your Lawn for more tips.
  5. Tree Roots. Tree roots can cause moss in a couple of ways. 1. The larger roots that grow close to the soil surface do not give the grass enough soil to dig into. Hence, moss develops and grows on top of these roots. When lawns are not watered deeply, the finer and even microscopic feeder roots of the tree can move upwards into the topsoil and compete with the grass for both water and space. This weakens the grass and permits moss to come in. This also can happen around shrubs that border the lawn, especially evergreens.
  6. Poor Mowing/Trimming. Poor mowing, mostly too short, can cause your lawn to change from one grass type to a less desirable type. In cases of very short mowing, or even scalping, no grass can survive. Usually you end up with low growing weeds or moss. The same holds true for those who use their “weed whackers” to trim the edges of the grass close to the ground. The short grass does not allow food production (photosynthesis) and has no chance for survival.
    Check back soon for a blog post on How To Properly Mow Your Lawn!
  7. Very Acidic or Very Alkaline Soil. As mentioned above, this is not the major cause of moss on most lawns. In extreme acid or alkaline conditions nutrients will lock up and become unavailable to the grass. This causes unhealthy grass and allows moss to fill in.
    If the pH of your lawn is extremely low you can balance it with Liquid Lime. If too high, take a look at our Liquid Sulfur.

To conclude, if you have moss growing in your lawn, look for the conditions that may be causing or contributing to it. Change what you can, and if you can’t change the conditions, try to appreciate the fact that this green carpet is covering what may otherwise be bare soil! 🙂

If you have any other questions about moss, please feel free to drop us a line at [email protected]!

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Mosses and Liverworts

These are the little ones. The most important feature of mosses and liverworts is that they have no vascular system. A vascular system in plants is a series of tubes that can transport water and nutrients over a distance. That vascular system of xylem and phloem allows redwood and sequoia trees to grow to over one hundred feet tall.

Limited in Size

Without a vascular system, mosses, and liverworts cannot grow very large. If you have seen mosses, you know that they are actually carpets of individual plants. They are rarely taller than one inch high. Another important characteristic of these little guys is that they require water to reproduce. It’s another characteristic of their low place in plant evolution. While all plants need water, mosses and bryophytes need droplets of water to enable their haploid reproductive cells to combine. They are all known as the bryophytes.

Mosses

Let’s start with mosses. These are waxy little plants with no leaves and no stem that use each other to stay upright. Their inability to stay up is why you never see one little moss plant; it’s always a group. That grouping also helps them retain water in the area. A waxy covering across their bodies helps keep water from evaporating. You will usually find them in moist areas out of the direct sunlight.

Good Worts

We’ll cover liverworts and hornworts together. If you can believe it, the worts are even simpler than mosses. These are considered to be the simplest of all plants and often grow flat along the ground in large leaf-like structures. None of the bryophytes have roots. They all have rhizoids (little hairs), and the worts are no exception. Like mosses, they are found in very moist areas, and some species even spend their whole lives in the water.
► Or search the sites…

Related Video…

Moonwort Discovery in California (Nat’l Forest Service Video)
Encyclopedia.com (Bryophyta):

Wikipedia (Moss):

Wikipedia (Liverwort):

Encyclopædia Britannica (Moss):

Encyclopædia Britannica (Liverwort):
http://www.britannica.com/EBchecked/topic/344697/liverwort

Bryophytes in arid areas

Ecology – Habitats

Many people are surprised to hear of bryophytes in arid areas. Surely such delicate plants couldn’t possibly survive in such harsh, dry environments! Arid environments certainly present considerable challenges but are home to many bryophytes. Sure, take a rainforest bryophyte into a desert and it won’t be able to survive. Is that really surprising? Take a rainforest vascular plant into a desert and it won’t survive either.

In hot, dry areas water is typically scarce, with rainfall unpredictable, and the bryophytes living there adopt various survival strategies. One is to grow in the more protected MICRO-HABITATS – such as at the bases of grass tussocks, on tree trunks, under boulder overhangs and in rock crevices, to give just a few examples. Consider the benefits provided by a tree trunk. A bryophyte growing on the predominantly shady side of a tree trunk will of course be protected from the full force of the sun. Additionally, the tree trunk concentrates some of the rain falling on the tree. During rainfall, some rain will fall directly on the trunk, some on the branches above, with some falling on the branches flowing down onto the trunk, so adding to the amount of water the trunk is exposed to. The benefits are greatly increased if the bark is rough and fissured. Such bark provides a much greater surface area (with numerous shaded micro-habitats) and slows down the flow of water, as well as providing numerous spots where a few droplets can be trapped, allowing any nearby bryophytes to benefit from the water over a longer period. Now turn your thoughts to a large boulder that is half buried in the soil in an otherwise barren area. During rain there will be runoff from the boulder. The soil around the base of the boulder gets water directly from the rain as well as the runoff. In a torrential downpour the contribution of the runoff may be irrelevant. But during light rain the runoff is likely to ensure that the soil near the base of the boulder stays wetter for longer than the soil further away from the boulder. The advantages created by trees, boulders or tussocks may be slight but, for some species, enough to create a tolerable habitat or sufficient to prolong benign conditions long enough to allow spore production.

Of course, you do also find arid area bryophytes growing in the open, but even here there are different microhabitats. For example, in the Southern Hemisphere a north-facing slope would undergo more heating than a south-facing slope, and vice-versa in the Northern Hemisphere. While some species would be able to tolerate either aspect, others would survive only on the more benign slope.

Arid area bryophytes open up and actively photosynthesize when there is moisture available, but close up and become dormant when conditions become too hot and dry. Bryophytes are much more resistant to heat when dry than they are when moist. Experiments have shown that species which can tolerate temperatures of 80-100°C (or even more) when dry, die at temperatures of 40-50°C if they are kept moist.

It’s a fact of physics that close to the ground the air is very slowly moving. This boundary layer is a result of the friction between moving air and the ground. It’s well known that still or very slowly moving air is a good insulator and it is also the case that molecules (for example, water vapour) move slowly through the boundary layer, since diffusion rather than convection is the moving force. Thus water, evaporating from the ground, is retained for a while within the boundary layer and creates a slightly more humid micro-climate. Arid area bryophytes growing on the ground are typically low growing and within that somewhat protective boundary layer. There’s more in the BOUNDARY LAYERS CASE STUDY.


Bryum argenteum top view

Many exposed mosses grow as dense carpets or small hummocks, each a colony of numerous plants. On the right is a close-up view of the top of a colony of Bryum argenteum. Each of those bumps is the top of a separate plant. Here is a side-on view of part of the same colony. In such dense colonies water is lost more slowly than in sparser growths. For one thing, the upper parts of such carpets or hummocks shade the lower parts and so slow down the loss of water from within the colony. Additionally, dense carpets or hummocks expand the boundary layer. Any roughened surface (such as the surface of a dense moss colony) that increases friction with the air will slow air movement and so modify the boundary layer. In effect, a moss carpet or hummock raises the boundary layer over itself.

Carpets or hummocks are a feature of the community as a whole. The separate gametophytes also have various structural features that help maximise the use of any available moisture. When mosses dry out there are various ways in which they close up. In some the leaves bend inwards at the base, finishing up flat against the stem. In others they curl up around the stem. In dry plants there are numerous very narrow gaps between neighbouring leaves or between leaves and stems that are ideal conduits of tiny amounts of water by capillary action. When water (even early morning dew) becomes available these channels help move it quickly throughout the plant. The leaves of many arid area mosses have papillae. A papilla is a tiny protrusion on the cell surface. It may be just a simple bump or it may be split or forked in some way. In a densely papillose leaf the gaps between the papillae provide numerous channels for rapid water movement by capillary action and so help spread, and thereby maximise the use of, tiny amounts of water. At the same time the tips of the papillae are likely to remain above the watery film and so provide places where the gas exchange necessary for photosynthesis can take place. As an aside it’s worth noting that papillae are not confined to arid area species, are also found in many of the leafy liverwort genera and are not always associated with capillary flow. For capillary flow the papillae need to be packed densely enough to create fine channels between the papillae and papilla shape may also be important. Studies have also shown that the tips of the papillae in various species are water repellent, thereby keeping them dry and available as sites for gas exchange. Many mosses of dry areas have slightly rolled up leaf margins. This creates a very narrow and somewhat tubular channel along the length of each leaf margin, Such channels also provide routes for capillary movement. The following drawing, by Judith Curnow, is of the moss Triquetrella papillata and shows part of a leaf surface in profile. You can see protruding papillae of various shapes. The black scale bar represents a length of 20 micrometres. Click on the drawing for another one showing the papillae of this moss.

scale = 20 µm (click to enlarge)

The moss family Pottiaceae has numerous genera and species, many of which are very common in harsh, exposed areas and are renowned for papillose leaves and curved leaf margins. To give you a rough idea of the prevalence of this family in dry areas, consider the book, by David Catcheside, given in the next reference button. It is a technical book with detailed descriptions of the mosses found in South Australia, predominantly a very dry state. The book deals with 31 families and has 184 pages of species’ descriptions and 84 of those pages are devoted to the family Pottiaceae. The next largest family (with 36 pages) is the Bryaceae. Of course, there have been changes in taxonomy and additional discoveries since the book was published in 1980, but the relativities suggested by those page counts would still be much the same today.

The leaves of many arid area mosses have white hairpoints at their tips. When the leaves of Campylopus introflexus are closed up they are hard to see but the hairpoints show very well . Here is the species Tortula princeps (a member of the family Pottiaceae) with the plants moist and the leaves showing very clearly – but you can also see the hairpoints quite easily. Hairpoints have more than one role. Hot, arid areas often become quite cool overnight. Cold nights may result in early morning dew or at least a relatively high night-time or early morning atmospheric humidity, especially near ground level. The multitude of hair points in a moss colony provide numerous condensation points, which give the colony a very effective means of gathering water. Those numerous hairpoints are also a source of friction between the moss layer and the passing air. Friction slows the airflow so the hairpoints help thicken the boundary layer. Another feature of those hairpoints is that they help protect the colony against overheating by reflecting some of the incident radiation. Experimental studies on mosses, comparing plants with hair points with those where the hairpoints have been removed, have shown that hairpoints can reduce water loss by about a third.

Leafy liverworts show little variation with changes in atmospheric moisture but few leafy liverworts are found in dry areas, especially in the open exposed areas in which you may still find many moss species. In dry areas you’d look for leafy liverworts in the more sheltered microhabitats.

In contrast to the leafy liverworts several genera of thallose liverworts are common in hot, dry areas.

Asterella drummondii – wet Asterella drummondii – dry

The photos above show the thallose liverwort Asterella drummondii with strap-like thalli. The species is often found well out in the open. When wet the thalli are open and green. Under much drier conditions that same colony takes on this appearance in the photo on the right. Now the thalli have rolled inwards, along their length, so that only fairly thin, black lines now show where previously there were green straps. On the underside of each strap there are blackish scales that act as a protective covering for the inrolled thallus. In the second photo the thalli have closed and all you see are the scales, which protect the thallus. Targionia hypohylla is another thallose liverwort found in fairly dry areas, though often in slightly protected micro-habitats. Many Riccia species are found in dry areas. The thalli are Y-shaped, the exact proportions (long and narrow, short and squat) varying between species. They are commonly found on damp soil in seasonally wet areas and this photo shows a colony of Riccia multifida in such a habitat. In this photo you can see a bryologist collecting specimens of Riccia. The habitat is the bare soil of a small dam in a forest in central New South Wales. The area is hot and dry for at least several months each year but in many years there is likely to be enough rain to raise the water level in this dam considerably. During the hotter months, as water evaporates from the dam, the water level will drop, leaving a temporary band of damp soil around the receding water’s edge. It is in such a damp band that this bryologist is searching, for it is there that you may find Riccia thalli in various stages of development. You can see the slightly darker band of damp soil in the photo. The thalli of Riccia also fold up along their long axes. Here we see Riccia lamellosa open and closed . The black scales on the underside of a closed-up Riccia limbata are even more striking. However, not all Riccia species have black scales. Riccia crinita has white hairs, as you can see in this photo . When closed, the hairs provide a protective layer. and also a means of trapping moisture.

A number of typically arid area bryophytes are individually short-lived, but persistent as a species, in a given area. In these bryophytes the gametophytes, typically small, develop quickly from spores, produce sporophytes and large spores and then die. A number of Riccia species fall into this category and examples amongst the mosses are the genera Acaulon and Ephemerum. The spores are often quite large, at times over a tenth of a millimetre in diameter, and incapable of long-distance dispersal. Such species are commonly described as annual shuttle species. Like the annual vascular plants (especially of the daisy family) that are common in dry habitats, the annual shuttle species do not tolerate drought but evade it by the production of drought-resistant sexual propagules. Because the large spores tend to move only very short distances, the annual shuttle species tend to persist in a given area for many years – not as individuals but as a species. The gametophytes of annual shuttle species tend to appear after rain in micro-habitats that are ephemeral but which tend to re-occur with some degree of regularity. An example of this is the damp soil around the forest dam shown in a photo a little earlier. At the other extreme are the perennial stayers, with far more robust gametophytes and with various adaptations to ensure long term survival as individuals. In arid areas the perennial stayers are best represented by the desiccation-resistant mosses but there are perennial liverworts as well. For example, with the genus Riccia there are perennial stayers as well as annual species. There’s a more detailed description of the various strategies in the LIFE-HISTORY STRATEGIES CASE STUDY.

Fossombronia levieri showing two tubers

Fossombronia is a genus of seemingly delicate thallose liverworts and a number of Fossombronia species are found in hot, dry regions. This photo shows some Fossombronia plants growing in a recently wet Australian arid area. You can see a number of black spore capsules, each atop a translucent stalk. You can also see that parts of the gametophytes are white. They are beginning to die. Here’s another photo showing a large number of white, dead Fossombronia gametophytes. Rapid spore production after a rainy period is one way in which a Fossombronia can perpetuate its species in an area. Fossombronia gametophytes, as they begin to dry out also produce tubers. The accompanying photograph shows such tubers. The plant in the photograph has been removed from the soil. When it was growing, all you would have seen above the ground was the long axis of the gametophyte with its flimsy, almost leaf-like outgrowths. The ends of the axis had turned down and produced swollen tubers beneath the ground. Eventually the above-ground gametophyte would die, leaving just the tubers within the soil. These tubers stay dormant in the soil until suitable rains come again, upon which the tubers produce fresh lettuce-like gametophytes.

Up the alps and near the poles

While many people will think of deserts when the word “arid” is mentioned the alps and the polar regions can also be considered arid. In very cold areas desiccation can be as great a problem as it is in arid areas. For example, in the polar regions water is abundant in principle, but much is locked away as ice, with free water being quite scarce in many places an it is free water that living organisms need. In all such areas strong, drying winds are another form of stress. Not surprisingly, you will also find polar bryophytes adopting many of the strategies outlined above.

Experiments have shown that many drought-tolerant bryophytes also tolerate freezing, if the freezing happens slowly. That is usually the case in natural conditions, with water slowly removed from the cells so that freezing leads to the formation of extra-cellular, rather than intra-cellular, ice crystals. Since water expands when it freezes, there is a danger that water within bryophyte cells would freeze and so burst the cells. Temperate and desert areas can experience freezing temperatures but clearly freezing is a much more common danger in very cold areas, such as polar and alpine regions.

At very high latitudes bryophytes are subject to very lengthy, even continuous light during the summer months. Experiments have shown that continuous illumination can cause some chloroplast disruption and so reduce photosynthetic activity. Continuous light is one stress that is clearly peculiar to the near-polar regions, the temperate and tropical parts of the world having distinct nights and days throughout the year.

On the subject of polar bryophytes and their adaptations, the bryologist RE Longton has noted that

None of these features, except perhaps tolerance of continuous light, can be regarded as a specific adaptation to polar conditions since all are shown by mosses growing in apparently more favourable environments … The success of bryophytes in polar environments thus appears to derive from attributes that are widely represented among mosses (sic) in general rather than from specific adaptations to polar conditions.

Longton also noted that most polar bryophytes are perennial stayers.

Written by Heino Lepp
Copyright and public access | Privacy Statement | Sitemap | Last updated: 15 April, 2008, webmaster, ANBG ([email protected])

Moss Gardens – Tips For Growing Moss In Your Garden

Growing moss (Bryophyta) is a lovely way to add a little something extra to a garden. Moss gardens, or even just moss plants used as accents, can help bring a sense of tranquility. Growing moss is not hard at all, but doing it successfully requires that you have a little bit of knowledge about what is a moss plant and what causes moss to grow. Keep reading to learn more about how to grow moss.

What is a Moss Plant?

Moss are categorized as bryophytes, which are non-vascular plants. While technically moss is a plant, it lacks the parts of a plant that we are used to seeing. It does not have true leaves, branches or even roots. Since moss has no roots, it must find other ways to absorb water and this is why it is frequently found in damp, shady areas.

Moss also does not have seeds like many other plants do. They spread by spore or division.

Moss tends to grow in colonies, with several plants growing closely together, which creates the nice, smooth carpet-like appearance that makes moss gardens so beautiful.

How to Grow Moss

Knowing how to grow moss is really just a matter of knowing what causes moss to grow. Things that moss need to grow are:

Moisture – As said, moss needs a damp location to grow, but will not do

as well in a location that is swampy.

Shade – Moss also likes to grow in the shade, which makes sense as moisture is more likely to linger in these areas and the moss will be less likely to dry out quickly.

Acidic soil – Moss also likes soil with a higher acidity, normally soil with a pH of about 5.5.

Compacted soil – While moss can be found growing in almost any soil type, most mosses prefer compacted soil, especially compacted clay soil.

How to Start Moss Gardens

The easiest way to start a moss garden is to simply build up the moss you already have. Many yards have some moss already growing in them (and many lawn enthusiast consider moss to be a nuisance). If you have moss growing in your yard, then you already know that the moss will grow in that location. Sometimes all it needs to grow thicker and more lush is a little fertilizer, a little more acid or a little more moisture. A 1:1 solution of water and buttermilk will help with acid an nutrients, as will powdered milk. You can also use an acid loving plant fertilizer on the area as well. When developing existing moss patches, it also helps to remove competing plants such as grass and weeds.

If you do not have moss in your yard or if you want moss to grow in a location where it does not currently grow, you will need to transplant moss. Moss can either be harvested (with permission and responsibly) from areas where it is already growing or it can be bought. If you harvest your moss, be aware that different moss grow in different locations. For example, moss plant harvested from the deep woods will not grow well in an open area with light shade. If you buy moss, the seller will be able to tell you what exact conditions that moss is suited for.

The best time to transplant moss is in spring or fall, when there will be the most rainfall. Transplant moss by laying a patch of moss in the location you would like for it to grow. If you have a large area you would like to cover, you can use a plug method, like you would with grass. Place small pieces of moss at regular intervals over the area. The moss will eventually grow together.

After you have planted your moss, water it thoroughly. Keep the area damp with regular watering for the next year or so to help the moss establish well. If the moss is allowed to dry out, it may die. Once established, transplanted moss should only need additional water in times of drought.

How To Grow Moss: A Simple and Fun Project

While some people are looking for ways to get rid of moss, others are trying to find ways to grow it. Learning how to grow moss is a fun and easy project that can involve the whole family.

Why grow moss?

There are many reasons you might want to grow moss:

♦ Moss is always green. Sometimes there are different shades, but it never turns brown unless it’s dead. And it’s tough to kill.

♦ Looking for excuses to mow less? Moss never has to be mowed.

♦ Have lots of shade where nothing else will grow? Moss grows in shade.

♦ Moss grows in ground that’s always wet or damp.

♦ Moss grows in compacted areas.

♦ Looking for a fun gift to give? It makes a great addition to DIY terrariums or fairy gardens.

♦ It is very easy to propagate. Here’s how:

Ingredients & Supplies

  • starter moss (see suggestions below or find it here)
  • buttermilk
  • bowl
  • potato masher or other tool for mashing
  • old paintbrush

Process

  1. Find some “starter” moss. Look around your yard, ask a friend, check local garden centers, or even the parking lot where you buy groceries. I found a nice clump where I buy my food. I asked the store manager if I could take it and he looked at me like I was nuts. He told me I could take all I wanted! So I gathered some up and took it home.
  2. Place moss in a bowl (I used one that I use for mixing soil) and then added some buttermilk. It doesn’t matter what kind of buttermilk you use. I think it’s the acidity and ability to adhere that makes a difference. Then I took an old potato masher and mashed it all up.
  3. When it looks like mud, use an old paintbrush to apply the moss onto any surface you want to grow moss. I painted mine on an old bucket, some rocks, and a dish I used to put succulents in.
  4. In a few weeks you’ll have moss growing all over the surfaces.

Alternatively, if you want more moss nearby some moss that is already growing, you can paint buttermilk on whatever surface you want to have moss on, and the spores should find it. (Sometimes this method works well, and sometimes it needs some help.)

Whatever your reason for growing moss, you’ll never have to mow it!

*******

Need help with what to do in your garden?

Q What exactly is moss?

A There are many species of moss, and a few are common lawn weeds. They are simple plants with thin cell walls that need a moist atmosphere to survive and reproduce. Wet, shady places are ideal for them. They are often found growing under grasses in lawns. Although they don’t flower and seed, they do produce masses of dust-like spores. These germinate into tiny filaments which eventually turn into the familiar feathery growth.

Spores are usually produced in the autumn, and again in the spring. Mosses that produce spores in the autumn survive into the spring to spore again, along with the plants from the autumn spores. When the weather turns hot and dry, the plants die out, but the spores survive and will grow when autumn rains return.

Caption: Rake up dead grass after mosskiller has blackened it

Q Why does moss grow in lawns?

A Moss grows in lawns when the conditions favour its growth, and if the growing conditions for lawn grasses are not at their optimum. When the grass is in full growth, moss is unable to compete. Mosses are favoured by low soil fertility, low pH (acid soils), compaction of the soil surface, poor drainage, lack of aeration, shade and sparse grass growth.

Q Could I mistake moss for anything else?

A Pearlwort (Sagina procumbens) is a compact weed that looks very like a moss at first glance. But, it has tiny white flowers between May and September, and is darker green and not as feathery. To remove pearlwort from your lawn, treat with a lawn weedkiller.

Q Is it absolutely necessary to control moss?

A Although moss looks nice and green in winter, it dies back in summer, leaving unattractive brown patches. Moss on its own will not tolerate wear – feet and mowers will leave marks, and it can wear away, leaving bald patches. Dead moss accumulates as ‘thatch’ at the base of the grass, preventing air and water from reaching the grass roots.

Q Does mowing affect moss?

A Close mowing can seriously weaken lawn grasses; they become sparse and cannot compete with weeds and moss. Aim to keep the grass 20mm in height. Mow regularly – during the growing season, utility lawns should be cut three times a fortnight. Longer, coarser grass can encourage moss, too. Aim to cut this to less than 25mm.

Caption: Adjust the height of your lawn mower lades so you don’t cut too low

Q How can moss in lawns be discouraged?

A The best way to discourage moss is to encourage the grass. Lawn grasses generally grow best on fertile, well-drained which gets plenty of sun. Most lawn grasses prefer neutral or slightly alkaline soil. Lawns growing on poor, sandy soils need feeding at least once a year and preferably twice. Different formulations of fertiliser are needed for spring and autumn applications, which should be applied when the soil is moist and the weather warm.

The pH of soils that are very acidic can be raised by the application of lime (ground chalk or limestone) during the winter at a rate of 60g per square metre. However, to be on the safe side, it is best to test the soil pH, either using a cheap test kit from the garden centre. One drawback of adding lime is that fine lawn grasses do best where the soil is acidic. Around pH 5.5 is ideal, so take care if you require a bowling-green finish.

Q What about problem areas?

A Drainage and soil aeration, particularly of compacted areas, can be improved by spiking with a garden fork to a depth of at least 7.5cm, or by hollow tining. Hollow tining removes a core of soil, which should be allowed to dry on the surface before being raked up. This is then followed by top dressing with a mixture of loam, sand and sieved organic matter brushed into the holes. The top dressing should vary depending on the type of soil. Heavy soils should be dressed with a sandy mixture, while sandy soils should be dressed with a mixture largely of organic matter. You can buy manual hollow tiners, which are hard work, or hire a hollow tine machine.

Lawn grasses grow most vigorously in open areas and growth becomes weaker as shade increases. Densely shaded areas are never likely to support good lawn growth. If shade can’t be reduced, try thinning or removing overhanging trees. Alternatively, consider replacing the lawn with groundcover plants, shingle, bark-chip mulch or paving.

Q Are there any chemicals for controlling moss in lawns?

A Ferrous sulphate is an option for treating large areas. It is found in lawn sand, which also contains fertilisers that encourage the lawn to green up.

Q When is the best time to control moss in lawns?

A Chemical controls are best applied in spring, when active moss growth resumes, or in autumn, before the onset of severe frosts.

Q What should I do with the dead moss?

A After applying a mosskiller, any moss in the lawn will turn black and die. However, it will be necessary to rake out the dead moss as its presence will continue to hinder the growth of the lawn. The raked-out moss makes an excellent contribution to the compost heap. Feed the lawn with a seasonally suitable fertiliser and lightly top dress if necessary. Sowing seed in sparse areas can be carried out in spring or early autumn.

Solving Moss Problems in Lawns

Moss invasions such as this call for adjustments in lawn growing conditions.

Moss invading lawns is a common problem. Moss thriving in lawns signals that grass is weak and has thinned for some reason, allowing the moss to take over. There are many potential causes, including excessive shade, compacted soils, poorly drained soils, low soil fertility, high or low soil pH, and poor air circulation. Poor lawn care practices are another source of moss problems. General lack of care, including irregular mowing and little or no fertilizer applications are common problems leading to poor turf growth.

Adding limestone is a common “remedy” mentioned for moss control, but is not suggested unless a soil test has shown the pH needs to be raised. Many soils in northern Illinois have high pH values; adding limestone will make this pH go even higher, adding to the lawn’s problem. Ferrous ammonium sulfate or ferric sulfate (iron sulfate) can be used to control moss to some extent. The moss will temporarily burn away, but tends to return fairly quickly. Raking out moss is another option; usually followed by reseeding.

Modifying site conditions to favor lawn grasses and discourage moss is a suggested way to manage the problem. Too much shade for acceptable grass growth is a common underlying cause for moss invasion. Pruning trees and shrubs to improve air circulation and light penetration is a good starting point. Evaluate the site to make sure the proper grass for the conditions is being used.

Take a good look at the soil conditions. A soil test can be helpful, as it could be the soil pH is out of line, contributing to the problem. Reduce soil compaction by core aerifying. This may also help correct drainage problems; although serious drainage problems may require more extensive work to correct.

Evaluate lawn care procedures, especially fertilizing. Lawns need adequate fertilization, in particular nitrogen. Established lawns in shady areas need less nitrogen than in full sun. About one to two pounds of actual nitrogen per 1,000 square feet per season is all that is needed in shade, compared to two to four pounds in full sun.

Also be sure additional lawn care practices are sound. Excessively short mowing may be a source of the moss problem; a range of 2½ to 3 inches is ideal for most lawn grasses. Mow on a regular basis (based on rate of lawn growth) to avoid removing more than one-third of the leaf blade. Also avoid excessive watering, as this may also contribute to moss problems. Water deeply and as infrequently as possible, based on lawn needs.

In this section : Weeds and Other Problems

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  • Managing Thatch in Home Lawns
  • Perennial Grassy Weeds in Lawns
  • Broadleaf Weed Problems in Lawns
  • Managing Crabgrass in Home Lawns
  • Solving Moss Problems in Lawns
  • Managing Lawns During Drought
  • Dealing with White Grubs in Lawns
  • Managing Patch Disease in Lawns
  • Managing Creeping Charlie and Violets in Lawns
  • Rust Diseases on Home Lawns
  • Fairy Ring and Mushrooms in Lawns

Garden Myths – Learn the truth about gardening

Lots of people want to know how to get rid of moss in the law, but a better question to ask is, “why does moss grow in lawns?”The most common response to this question is that the lawn receives too much shade and that the soil is acidic. The common advice is that grass will grow better if you limb up the trees and add lime to the soil to make it less acidic. Or you can spread a moss killer for lawns.

What about moss that is growing in a sunny area? What about moss growing in soil that is alkaline? There is much more to the moss story and the only way to really get rid of moss in a lawn is to understand why it is there in the first place.

Mossy alkaline bolder at Aspen Grove Gardens

Moss in Lawn is Not a Sign of Acidic Soil.

Moss does prefer to grow in acidic soil, but it will grow just fine in alkaline soil. Part of my lawn is shady, wet and has a pH of 7.4. Moss grows much better than grass in that area. The picture above is a 4 foot high limestone bolder that is covered in moss – it is certainly not acidic.

The common advice of liming the soil will make it less acidic if done properly, but it will not get rid of moss. Liming can actually make the situation worse. Unless you know for sure that your soil is too acidic for growing grass, do not add lime.

Moss is one of those plants that can grow in spots that are inhospitable to other plants, including:

  • Too much shade
  • Too wet
  • Compacted soil (ie lack of air in the soil)
  • Low fertility

When you have moss in your lawn, the moss is not the problem. The real problem is that you are trying to grow grass in a spot where it will not grow well. If the grass is not growing well, moss takes advantage of the situation and moves in. Moss will not invade a healthy growing lawn.

Moss Killer

You can spread lawn moss killer, which usually contains some form of iron sulphate (ferrous sulphate or ferrous ammonium sulphate). This will kill moss since moss does not grow well with high levels of iron in the soil. You can also rake out the moss and physically remove it from the lawn.

The problem with either if these options is that they do not work long term. Unless you fix the real problem ie grass not growing well, the moss will soon return to the lawn. There are really only two options. Leave things alone and embrace the moss as a natural ground cover, or fix the problem so that the grass grows better.

How to Get Rid of Moss in a Lawn?

In order to fix the problem, you need to first identify the problem, but any or all of the following will improve the growing conditions for the lawn.

– Reseed with shade tolerant varieties of grass – if the area is shady

– Aerate the soil – reduces compaction

– Add organic matter to the soil

– Fertilize more if there is a nitrogen deficiency

– Reduce the amount of shade ie thin or limb up the trees

– Water less if it is a wet area, water more if it is a dry area

– Cut grass higher to encourage stronger grass roots

Moss Grows in Full Sun

It is a myth that moss grows only in shady wet areas. There are many kinds of moss and some of them like to grow in dry sunny areas, even desserts. Sun loving moss will invade a sunny lawn.

Moss is Not Always Moss

There are some garden plants that look like moss and some that even have ‘moss’ in their name. The following are not true mosses

  1. Spanish Moss (is an epiphyte)
  2. Caribou Moss (is a lichen)
  3. Iris Moss (is a vascular plant)
  4. Scotch Moss (is a vascular plant)

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