Garden Myths Gardening Laidback Gardener Tip of the Day

Using Lime to Control Moss: Another Garden Myth!

20160115AThere is nothing worse than a gardening myth that refuses to die, especially when it causes gardeners to waste their money. And this is the case with the stubborn belief that you can eliminate moss from a lawn or garden simply by applying lime. Unfortunately, even garden centers repeat this false information, with the result that their customers are misled. No, lime will not kill moss: applying it to do so is just throwing your money out the window!

This myth derives from the belief that moss only grows in acid soil and therefore, if there is moss in your lawn or garden, the soil must be acidic. But in fact, mosses are highly adaptable plants that will grow in acid, neutral and even alkaline soils. What the presence of moss really does tell you is that the soil is of poor quality, period. When other plants grow poorly, moss, being highly adaptable, moves in, occupying the empty space. The moss itself is not the problem, it is a symptom of poor growing conditions.

When you see moss in your lawn, your flowerbed or vegetable garden, five factors may be involved:

  • Deep shade;
  • Poor soil (lacking in minerals);
  • Soggy soil;
  • Densely compacted soil;
  • Highly acidic soil (pH less than 5.5).

In fact, it is usually a combination of these factors that so hampers the growth of other plants that moss is able to move in. Maybe the soil is compacted and shaded, or poor, soggy and acidic.

Some of these factors are easy enough to judge for yourself. You can easily see whether the location is shady and if the soil squelches when you walk on it, you can be sure the soil is soggy. Try to push a pencil into it: if that is hard or impossible to do, you can be pretty sure it is too compact.

There really is no easy way, however, to spot acid soil or mineral-poor soil at a glance. For that, you need to do a soil test. Especially, never apply lime before making sure that the soil really is suffering from excessive acidity. Lime is toxic to plants if misused!

How to Truly Eliminate Moss

The only real secret to controlling moss is make sure the conditions are better for other plants. Aerate the soil if it is too compact (you can mix in lots of organic matter), drain it if it is soggy (perhaps by adding a raised bed), enrich it with compost or organic fertilizer if it is poor, thin out overhanging branches if it is too shaded and of course don’t hesitate to add lime if the soil test does indicate that the soil is very acid. Once that is done, other plants will be able to prosper and they will slowly, over time, take over and chase the moss out (moss won’t tolerate competition).

Mulch will initially cover and kill moss… but if you didn’t improve the soil first, it will eventually grow back on top of the mulch.

This isn’t going quickly enough for you? After making necessary changes, simply mulch the soil of your flowerbeds or vegetable garden. Mulch will cover the moss and cut off its source of light… and without light, it will die.

Moss in Lawns

You can’t mulch a lawn like you can a flowerbed, since mulch will cut off the light to the grass and kill it too. Instead, try the following:

20160115BFirst, fix the growing conditions. If not, all your efforts will be in vain.

Now, spray the area with one of the various anti-moss products (prefer an organic soap such as EcoSense Moss B Gone, widely available in garden centers) to kill the moss initially. Then rake it off and sow the area with grass seed. Try to use grass seed adapted to your conditions (there are mixes for partial shade, for example, if shade is part of the problem). If you don’t, the grass seed won’t take hold and, if there is nothing else there to take it’s place, the moss will return.

Why Eliminate the Moss At All?

Personally, I think this is the real question to ask. What is so wrong in having moss in your landscape?

Moss can be beautiful: why eliminate it?

Unless you live in a rainforest where the extreme and constant humidity can allow moss to grow up and over lower-growing plants, smothering them, moss usually hugs the ground and is not harmful to other plants. Instead it is “filling in the blanks”, growing where other plants won’t. In fact, moss is even beneficial. It is essentially a living, self-maintaining mulch, growing naturally as an understory in forested areas, creating a moss layer that moderates abrupt temperature changes to the roots below, helps to keep the soil from drying out too deeply, contributes to enriching the soil and reduces weed growth. It can even form a beautiful green carpet quite as beautiful as any grass lawn. And moss between paving stones? How beautiful is that!

Of course, when the moss grows on man-made structures (roofs, wall shingles, etc.), you do need to control it as it reduces their useful life, but in a garden or in a lawn… why not learn to appreciate its beauty and its benefits rather than seek to eliminate it?

Too often human beings think they know better than Mother Nature… but in my opinion, she is almost always right!

Here’s a blog on how to grow moss rather than eliminate it.

Garden writer and blogger, author of 65 gardening books, lecturer and communicator, the Laidback Gardener, Larry Hodgson, passed away in October 2022. Known for his great generosity, his thoroughness and his sense of humor, he reached several generations of amateur and professional gardeners over his 40-year career. Thanks to his son, Mathieu Hodgson, and a team of contributors, will continue its mission of demystifying gardening and making it more accessible to all.

5 comments on “Using Lime to Control Moss: Another Garden Myth!

  1. Thanks for this article. We are starting a new garden after just moving. Where we are putting the garden is almost all moss. Do you see a downside to just tiling it in? We need to aerate in order to plant and we’re also planning to get some organic matter/composted manure and mix it in as well. But should we try to remove the clumps of moss or is it ok to till the moss into the soil? Is it going to rob nitrogen or cause us any more issues? Thanks!

    • Why not just till it into the soil? Moss plants have no roots and therefore don’t really use the resources in the soil, so they certainly won’t steal nitrogen. They get their resources from the air and rain.

      • Just what I wanted to hear! Thanks!

  2. Margaret

    I love moss! Recently, I had my house painted. The contractor looked at the moss growing between my brick pavers and said ‘oh, we can get rid of that when we power wash. Your path will look brand-new’. When I protested that I didn’t want it to look brand-new, I got the usual blank stare. Sigh.

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