Sphagnum peat moss has been a lifesaver for my gardening, as my home is built on top of dense, alkaline clay. The addition of peat moss to my garden, along with liberal amounts of compost, has done wonders to regulate the soil pH and transform the clay to loam. Peat moss is also the best natural, long-term soil acidifier for acid-loving plants like blueberries, rhododendrons, strawberries, hydrangeas, and dogwoods. But using peat moss is controversial, as it’s considered a non-renewable resource: it’s harvested from vast carbon sinks called peat bogs, which help us in the fight against climate change.
What is peat moss?
Sphagnum peat moss, aka sphagnum peat, is a soil conditioner used by gardeners and farmers to lower soil pH (make it more acidic). It also increases the ability of sandy soils to hold water and improves the drainage and gas exchange capacity of clay soils by adding pathways for air and water. Unlike other organic materials like mulch and compost, peat moss does not decay quickly and lasts in soil for many years.
Where does peat moss come from?
Peat moss is harvested from a type of wetland called a bog. In the bog, plant materials submerged underwater, mostly sphagnum moss, decay over thousands of years, building up layer after layer. This eventually becomes a soil-like material called peat. To harvest peat, the bog is drained, and the exposed peat is cut and vacuumed up. Then it’s dried, screened, and compressed into the bales and other products sold at your local garden center.
The majority of the peat moss sold in North America is harvested from drained bogs in Canada or Michigan, U.S. Besides bales, peat also appears as peat pellets for starting seeds, biodegradable peat pots, and as an ingredient in potting soils. Due to its sustainability question, peat produced in Canada is only harvested after an environmental analysis and impact study and is done. It is then harvested using sustainable methods. Even though the peat in a bog may have been accumulating for hundreds or thousands of years, research shows that harvested bogs can be restored within 5 to 20 years.
The controversy around using peat moss in your garden
Peatlands… play a critical role in global warming. They are the largest terrestrial carbon sink, holding more carbon than all forests or grasslands. They cover only 3 percent of the land, but contain 30 percent of the carbon.
National Gardening Association
Bogs are a type of peatland, which are wetland ecosystems that trap 1/3rd of the world’s soil carbon. Each bog is a natural carbon sink of immense proportions (it absorbs carbon dioxide from the atmosphere). When peat is harvested from the bog, this carbon is released back into the atmosphere, contributing to climate change.
In 2016, the U.N. launched the Global Peatlands Initiative to protect peatlands, “which contain almost 100 times more carbon than tropical forests.” Besides trying to restrict peat harvest, the initiative also protects peatlands from spontaneous fires caused by deforestation, which can take many lives.
According to The Washington Post, “the extraction of peat requires the removal of a bog’s living surface to reach the partially decomposed layers beneath. It grows at a mere sixteenth of an inch a year, and its mining removes layers that take centuries to develop.” In Great Britain, using peat is now restricted and the government is phasing out peat moss for hobby gardeners and agricultural use. The Royal Horticultural Society, the largest gardening organization in the world, has reduced peat use by 97 percent at its four major gardens in England and urges its members to do the same. Britain has lost 95% of this natural resource, as much of the peat was harvested for burning as fuel over hundreds of years.
The Canadian Sphagnum Peat Moss Association pushes back on claims of harvesting peat bogs and its environmental effects. Canada, which leads the world in producing peat moss, contains more than 280 Million acres of peatlands. Of that vast amount, only 73,000 acres have so far been harvested, a fraction of the quantity naturally generated in undisturbed bogs. The group’s members take the restoration of each harvested bog seriously. After harvesting, each bog is reflooded and reseeded with shredded moss grafts, which cover the harvested site within 5 years. The peat bog is naturally restored in 10-15 years.
Why use peat moss as a soil amendment?
- Peat moss is brilliant for slowly acidifying your soil over the long-term. It has a pH of between 3.0-4.0.
- It’s inexpensive.
- In rocky or sandy soil, which dries out quickly, peat moss will absorb and hold water longer than the soil, making moisture more available for plants.
- In dense clay soil, it increases porousness, air capacity, and drainage.
- Peat moss contains no weeds, insects, or diseases.
- It is naturally sterile and contains few microorganisms.
- Peat moss is approved for organic gardening.
4 peat moss alternatives
Peat is preferred as a natural acidifier for soil when planting blueberries, rhododendrons, azaleas, and similar plants. If you’re only using peat moss for its aeration qualities, try these instead:
*Peat moss should not be used as a mulch, as it will densely pack when wet and restrict water from entering the soil – it should always be mixed in with the top layer of soil.
1. Compost
A fantastic soil conditioner packed full of nutrients your plants need.
2. Coir
Coir is a fiber made from coconut husks and has the same water holding capacity and porosity as peat moss. But one can argue that coir has a large carbon footprint, as coconuts are grown on plantations in Asia and must be shipped to gardeners worldwide. Coir dust and Cocopeat are also made from coir.
3. Pine Bark
Finely shredded and composted pine bark is not only an excellent mulch but also a fine soil amendment when used with other members of this list.
4. Worm Castings
The excrement of Earthworms, worm castings, are harvested and sold as a natural fertilizer. They are loaded with nutrients and beneficial microbes your plants need.