How Much Light Does Moss Need? (List Included)

Providing the right amount of light is essential to growing moss indoors.

Mosses can survive in low light but to thrive they require light to photosynthesize.  Depending on the species, some moss species (e.g. Broom fork moss, Pincushion moss) can thrive in partial shade; But a large number of moss species (e.g. Haircap mosses) require strong light to photosynthesize.

Let’s explore the list of low-light moss species and those that require strong light.  We will also look at how you can best provide the right amount of light indoors.

List of low-light moss and light requirement

A small number of mosses can survive in partial or even consistent shade.

According to a study that examined 39 species of mosses in England, one-third of the moss species studied could carry out full photosynthesis under rainy or cloudy days with only 20% of full sunlight (Marschall & Procter, 2004).  These moss species inhabit shaded, damp areas beneath a tree canopy with indirect light.

These mosses could achieve full photosynthesis with only 100 to 300 µmol/m2/s PPFD of light which is the equivalent of the light intensity on a rainy or cloudy day.

Here is a list of 12 moss species which reach full photosynthesis in ascending order of light intensity:

The intensity of sunlight is measured in Photosynthetic Photon Flux Density (PPFD) values, which is the number of photosynthetically active radiation (PAR) photons per square meter per second. 

(If you would like to measure the intensity of light received by your indoor moss and plants, you can check out our recommendations of PAR meters for plants.)

List of high-light moss and light requirement

The majority of moss species do require strong light to perform photosynthesis.

According to the same study (Marschall & Procter, 2004), two-thirds of the moss species studied achieve full photosynthesis under a much stronger light intensity of between 500 and 1000 µmol/m2/s PPFD with a few species reaching even over 1000 µmol m−2 s−1 which is close to full sunlight intensity.

Species that are adapted to photosynthesize under high light conditions are those that live in exposed and wet habitats such as peatlands, bogs, springs, etc. which remain constantly moist and so they do not dry up under full sun.

Here is a list of 23 moss species that reach full photosynthesis, in ascending order of light intensity:

Can moss survive in low light?

Generally, moss can survive in low light.

Moss species that can grow under low light have higher levels of light-capturing chlorophyll to carry out photosynthesis, compared to the species that inhabit bright-lit environments.

Apart from photosynthesis, mosses can absorb nutrients and water directly from the environment.  Mosses generally have a much less complex structure compared to flowering plants.   Mosses are bryophytes.  They are primitive, non-flowering plants that do not have specialized vascular structures to transport water and nutrients from the roots to other parts of the plant.  Their cell walls lack lignin and are thus very thin and can absorb water and nutrients from the environment directly throughout their entire body.

Their small size and less complex body structure also result in lower energy demand, enabling them to thrive in low-light environments.

Mosses also do not have true roots like flowering plants. Instead, they have structures called rhizoids, which are small cells that stems grow out of.  Rhizoids anchor the moss to surfaces and help with water absorption. This unique structure allows them to absorb water and nutrients directly from the environment, rather than relying solely on sunlight for photosynthesis like other plants do.

Can too much light harm mosses?

Intense or direct sunlight can cause damage to some types of moss by burning their leaves (liverworts) and drying out their rhizoids (multi-celled anchoring structures). In contrast, some moss species can withstand partial sunlight for up to 8 to 10 hours or more as long as they are not exposed to constant and direct sunlight.

Signs that mosses may be receiving too much sunlight include dried-out or brittle areas, discoloration, and a reduction in growth rate. Browning or yellowing of moss leaves and a thinning appearance can also indicate that the moss is struggling under the sun’s intense rays.

On the other hand, mosses that do not receive enough light may exhibit limited or stunted growth. Since mosses require light for photosynthesis and energy production, a lack of sufficient light can result in weak or sparse growth patterns. Additionally, mosses in shaded areas may experience increased competition for nutrients and space from other shade-tolerant plants.

How to provide light for moss indoors?

One great option for growing moss indoors is placing it near a window that receives about two hours of morning light, as this is ideal for moss growth. Morning light is gentle, ensuring that mosses won’t be exposed to harsh sunlight. If you don’t have a suitable morning light window, you can move your moss container to a bright spot out of direct sunlight for the rest of the day after its initial exposure.

Filtering sunlight through a sheer curtain can protect moss from the intensity of direct sunlight while still providing enough light for their growth.

Using a dedicated grow light, placed a suitable distance from the moss to prevent overheating, is another option for maintaining consistent light throughout the day.

By finding the right location and ensuring the proper amount of indirect light, you can create a thriving moss garden inside your home.

Happy gardening!

Related

Top 16 Mosses for Indoor Plants & Living Wall

Top 8 PAR Light Measurement Meters for Plants

Reference

Marschall, M. & Proctor, M. C. (2004).  Are bryophytes shade plants? Photosynthetic light responses and proportions of chlorophyll a, chlorophyll b and total carotenoids. Ann Bot. 2004 Oct;94(4):593-603. doi: 10.1093/aob/mch178 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4242232/

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Carol Chung

Editor and Founder at AskGardening

Carol is a journalist, teacher, and plant lover. Over the past 20+ years, she has nurtured countless potted plants and orchids in small indoor spaces. Her expertise also extends to growing natural, organic vegetables in farms in South America. Passionate about sharing her knowledge, she writes to help others to create their beautiful gardens. Discover more about Carol.

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