Sphagnum moss and sphagnum peat moss are terms used to refer to two different forms of the same plant. Both are interchangeably referred to as peat moss. But the way you use each form is different.
In this article, we look into the difference between sphagnum moss and peat moss, as well as offer some gardening tips on how to use each one. Lastly, we look into how they are harvested and the aspect of sustainability.
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Difference between sphagnum moss vs peat moss
Sphagnum moss grows on the damp surface of soil or in a swamp. It is a living plant that thrives in most places with wet climates and is commercially produced from the wetlands of New Zealand, Canada, Michigan, Ireland, and Scotland.
A cycle of growing sphagnum moss takes about 5 to 6 years and so careful harvesting must be done to ensure a continuous supply. It is harvested and dehydrated for use in gardens, greenhouses, and reptile beddings in terrariums.
On the other hand, peat moss or sometimes called sphagnum peat moss is partly decaying dead sphagnum moss and other organic material that settled in bogs. It may contain other plant material and even dead insects, and so may not be purely made of sphagnum moss.
Through a natural process that spans thousands of years, the organic materials sink in the bottom forming layer upon layer of compressed peat moss. The decomposition happens very slowly without the presence of air which slows down the rate of decomposition.
Properties of sphagnum moss and peat moss
Sphagnum moss and peat moss also has different physical and chemical properties like:
Sphagnum moss has a neutral pH as compared to the lower, more acidic pH (3.0 to 4.0) sphagnum peat moss. Peat moss is a less expensive amendment in potting and garden soils, and it is a great medium for growing acid-loving plants. Peat moss is also high in tannins.
Water retention is excellent for both. Peat moss can retain up to 70% water.
Sphagnum moss has discernable plant parts, is very pliable, long-fibered, and has a soft spongy texture while the sphagnum peat moss is more decomposed with no recognizable plant parts, has short fibers, and finer texture.
Sphagnum moss is commonly used as a seed-starter medium, used to line baskets for growing orchids and other moisture-loving plants like alocasia, begonia, and calathea. It is also used as an amendment to potting soils and garden soils.
Sphagnum peat moss often labeled as peat moss are products that are commercially sold in compressed bales or bags. They are also dried and milled to be used in potting and gardening soils.
Sphagnum moss for the propagation of indoor house plants
Sphagnum moss is great for propagation because it can hold up to 20 times its weight in water. It also provides excellent airflow to the roots preventing root rot. This makes it easier to achieve healthy roots that need just the right amount of water, oxygen, and nutrients.
Sphagnum moss is sold in two forms labeled: (1) long-fibered moss or (2) milled moss. They are the same moss but the long-fibered moss is its natural form while milled moss is finely chopped. Each has its preferred use.
Sphagnum moss is bought dried and shrunk in wrapped bags and it expands once hydrated. Simply add water in a large container with the sphagnum moss to hydrate it. The moss will expand a lot so make sure the container has a lot of space. Leave it there for about 15 minutes and once you are happy with the size it has expanded, squeeze out the excess water.
To propagate a plant, place the hydrated sphagnum moss in a clear container. Using a transparent clear container allows you to see roots growing without disturbing the plant. Additionally, you can also see if the moss gets too dry removing the guessing game.
It is also good to not pack the moss in too tight. Keep it loose allowing air gaps for good airflow.
Bury the nodes of the plant that you want to root into the sphagnum moss.
You can grow plants in moss for the long term but remember that sphagnum moss does not contain any significant nutrients for the plant’s roots to absorb. You have to supplement it with other nutrient-giving materials like leca (lightweight expanded clay aggregate).
Once you see the roots grow up to a few inches long, move it to another growing medium for the longer term.
Peat moss is used as a soil amendment in potting soil or raised vegetable garden beds. It is preferred for extremely dry areas because it retains water well, and also to keep nutrients from being washed off. But be mindful that it can change the acidity of the soil and might require lime to neutralize.
Epic Gardening shared tips on how to prepare peat moss for garden soil:
As a soil amendment, apply 2 parts soil to one part peat moss ratio. Thoroughly mix the gardening soil to distribute it well.
The mix for seed starters will vary based on preference. Soilless mixes use peat moss as the base with equal parts of perlite or vermiculite, and small amounts of lime and fertilizer for pH and plant nutrients. It is best to fit the ratio to the needs of specific crops.
The sustainability aspect of harvesting peat moss
It takes thousands of years for peat moss to form. Harvesting requires digging up bogs which destroy possible regeneration of the swamp environment. This is why it is not considered a sustainable practice.
According to the University of Vermont, about two-thirds of the world’s wetlands are peat, and about seven percent have been used for agriculture. In Canada, only about 0.02 percent is harvested yearly, or about one million tons. At the same time, an estimated 70 million tons of peat is being created naturally each year.
Research studies show that it takes 5 to 20 years after stripping for harvested peatland to return to an ecologically balanced system. Peat itself forms a layer of an inch every 15 to 25 years.
Companies first harvest the living plant sphagnum to gain access to the bog. They then dry out the bog temporarily so that they can harvest the peat with vacuums. The peat is further dried, screened, and compressed into bales which is what is sold commercially in stores.
In 2010, the United Kingdom encouraged both households and commercial growers to use more environmentally friendly alternatives. This is to protect the habitats of rare plants and animals in peatlands and to prevent flooding in nearby towns and cities.
When peat moss is dried out before being harvested, it releases around 400,000 tons of gases every year which is the equivalent of what 100,000 cars on the road produce. The bogs continue to exhale carbon long after the harvest has finished.
Acts and regulations have been established to control and manage the environmental impacts that harvesting peat moss poses. But consumers are still encouraged to look for alternatives.
Sphagnum moss can be substituted by leca or pumice for propagating and growing houseplants.
Coconut coir or coconut matting, wood fiber, composted bark, or green compost can be used as an alternative to peat moss as a soil amendment. Coco coir comes from milled coconut husks and is often considered a waste product.
Why is sphagnum called peat moss?
The confusion in terminology stems from not understanding that sphagnum is the genus of moss species. Peat moss is sometimes called sphagnum peat moss because the main material that makes up a peat bog comes from sphagnum moss that grows on top of the bog.
Can you use peat moss instead of sphagnum moss?
Each has its preferred use. Sphagnum moss is preferred when propagating plants or in seed starters while peat moss is often used as an amendment to gardening soil.
Is sphagnum peat moss renewable?
Not really despite what companies say. Although regulations are set in terms of the amount of harvestable peat that is allowed, the bogs hardly regenerate themselves because of the very slow natural process to make peat.