Moss doesn’t have roots - instead it has rhizoids. It is these root-like structures which allows moss to attach itself to rock surfaces and flourish and grow.
Mosses are small, flowerless plants that grow and thrive in moist areas. Although they produce energy through photosynthesis, like other plants, they don’t have seeds and their roots are extremely shallow.
These roots, or root-like structures, are called rhizoids. The major benefit of these rhizoids and their shallow nature is that they allow moss to attach itself to rock surfaces, where it can then suck or absorb the moisture that runs over the rock. This commonly takes shape through rainwater or streams. The moss is a clever survivor species in this respect, and this method of growing and surviving on rocks explains its longevity on earth.
As an example, I live in Wales, a country which gets its fair share of rainfall throughout the year. This means the rocks in my garden provide the perfect habit for moss to thrive. Some people find it unsightly, but I don’t mind it as it adds a bit of character to the garden. What’s more, moss doesn’t feed on living organisms. So it doesn’t have a damaging effect on my other plants.
How long does moss take to grow on rocks?
You might have recently treated yourself to a new garden, and therefore wondering how long it might be before you can expect moss to appear on any stone surface. Or you might be actively trying to grow moss to give your garden an authentic woodland feel and aesthetic.
As an ancient, primeval plant, moss tends to grow particularly slow as it doesn’t have a highly developed vascular system. The growing conditions will also affect the pace of growth. If your garden tends to trap a lot of moisture, or there are a lot of sheltered or shaded areas covering rock surfaces, this will provide moss with a fruitful growth habitat. You could also spray your rocks regularly to ensure they get enough moisture for moss to thrive off, or position your rocks in an area that will catch a fair amount of sun if you don’t want excess moss growth. The sun will naturally dry moist rock surfaces, and thus deprive moss from getting its must-have nutrients.
You might want to put a layer of soil between the rocks you wish to grow moss on, as this will encourage growth. Vice versa for if you want to discourage growth; don’t clump your rocks or stones together and remove any soil between them.
There are two types of moss; acrocarpous and pleurocarpous
What are the most common types of moss to grow on rocks?
First of all, we need to establish the two types of mosses; acrocarpous and pleurocarpous.
Acrocarps grow simply or sparsely forked. They also grow erect, so often form a colony that is heaped into a neat, round pile. One common acrocarpous moss that grows on rocks is Swan’s-neck thyme moss, also known by its Latin name Mnium hornum. You tend to find it a lot in woodland or forest conditions, but it can also be found in gardens. It clings to rock ledges and surfaces, especially those in acidic conditions and often exposed to moisture.
Pleurocarps, on the other hand, contain free branches that grow and spread in a more unruly, chaotic manner compared to acrocarps. Due to this unformulated growth pattern or structure, they tend to grow faster on rocks that acrocarps. That’s because they attach to rock surfaces more easily. If you’re looking to grow moss on rocks for an aesthetic effect, pleurocarps could be a better choice for you as they:
- Are easier to maintain than acrocarps
- Can tolerate moist conditions, whereas acrocrops risk rotting in similar conditions
- Flourish all year round with sufficient watering
Although moss thrives on moisture, mold can also grow in a damp or wet environment. As it does with most things, it can damage and kill moss - not to mention have an unpleasant aesthetic effect. So be careful to control the moisture retention in your garden. Don’t overwater areas you want moss to grow in, sprinkle water on rock surfaces in small, gentle sessions, and allow natural rainfall to do this job for you whenever possible.
Hopefully you've enjoyed this blog and you now know what moss grows on rocks. If you are interested I've also written a post on What causes moss to grow on soil?
