Peat has long been a staple in commercial potting mixes, but growing environmental concerns are prompting gardeners to seek more sustainable, peat-free alternatives.
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Peat in the Headlines
The use of peat in gardening is a hot topic right now—especially in the United Kingdom, where a ban on retail peat sales is expected within the next year or so. The Royal Horticultural Society has also announced it will no longer allow peat at its garden shows.
Here in North America, the issue hasn’t gained the same traction—though awareness is growing.
Many gardeners don’t even realize they’re using peat. Even if you never buy peat moss as a stand-alone product, chances are it’s still in your garden.
That’s because peat is a common ingredient in most commercial potting mixes—unless labeled peat-free. It shows up in bagged and bulk soil, seed-starting mixes, and the growing media used for nursery plants.
But I’m getting ahead of myself. Clearly it’s readily available and useful, so what’s the big deal? Why is peat being singled out as a problem?
The issue is not the peat itself. It’s how it’s mined that’s the problem.
The extraction of peat essentially decimates wetlands—a vital part of our ecosystems—and life on earth.
Let’s look at peat—what it is, how it’s used, and why peat extraction raises environmental red flags, even here in Canada where vast peatlands still exist.
This article is based on the episode Peat in Gardening: What’s the Problem?
from our podcast, Two Minutes in the Garden,
available wherever you find your favorite podcasts.
Peat 101
What is Peat?
Peat is slightly decomposed organic matter. Specifically, it’s organic matter from wetlands that has accumulated and partly decomposed over the course of centuries or millennia.
Sphagnum Peat
These days, when we talk about peat, we’re almost always referring to the Sphagnum genus and its hundreds of species. Other organic matter can get into the peat—bits of dead plants, microbes, insects—but it’s mostly Sphagnum.
Like all mosses, Sphagnum mosses are plants without roots, so they take in water and nutrients through their leaves and stems. Mosses have specialized cells that can hold a lot of water like a sponge.
Why Peat is Slow to Decompose
It’s quite interesting why peat doesn’t just rot and disappear into bogs.
In a compost pile, we expect organic matter to decompose within a few months to a year. So how is it that peat remains only slightly decomposed after centuries?
There are several reasons:
- Low Oxygen | Peatlands are wet and waterlogged and that water contains very little oxygen. There are oxygen atoms in the water molecules, but those aren’t available as oxygen and there’s not much dissolved oxygen in the water. This lack of oxygen greatly reduces the microbial activity needed to drive decomposition.
- Carbon Heavy | Peat is very carbon-heavy. Its high carbon-to-nitrogen (C:N) ratio is similar to straw. We don’t usually think of moss as a “brown” in composting terms, but it is. There’s not much nitrogen (“green”) to balance things out, which slows decomposition even further.
- Acidic | Living Sphagnum mosses create acidic conditions. They don’t play well with other species, and their acidity also slows decomposition.
- Cold | Many Sphagnum peatlands are in colder areas, where microbial activity slows down—just like in a compost pile during winter.
So even after centuries, peat only decomposes a little. Meanwhile, more is added every year as mosses reach the end of their life cycle, but the amounts are minimal. In Canadian peatlands, this natural accumulation is less than a millimeter a year—typically about the thickness of a credit card. But, over hundreds or thousands of years, that adds up to deposits several meters thick.
As soon as I heard “less than a millimeter a year,” a red flag popped up. But environmental concerns were not on our radar back when peat entered the gardening world.
Historical Use of Peat in Gardening
Peat has a long history in gardening, especially in the UK where recommendations to use peat as a soil amendment date back to the early 1800s.
We start seeing peat mentioned for agricultural and some horticultural use in the U.S. by the 1920s and 30s.
It really took off in the 1940s and 50s.
- A 1959 edition of “10,000 Garden Questions Answered by 20 Experts” contains over 400 references to peat and peat moss.
- Rodale’s “Encyclopedia of Organic Gardening” from the same year mentions it over 200 times.
It was around that time that peat became the base for many potting mixes, usually mixed with materials like perlite or other components.
Why Peat Became Popular
We know organic matter is beneficial for soil, improving structure, drainage, reducing compaction, supporting microbial communities, and more.
But why did peat in particular become the go-to base for potting mixes as far back as the 1950s?
That answer is two-fold. The desirable qualities found in peat and the marketing.
- Excellent water retention | Peat is light and fluffy—great qualities for a potting mix. But for something so light, it holds an impressive amount of water—typically 15 to 20 times its weight. That’s thanks to those specialized cells in Sphagnum.
There is a downside: when peat dries out, it becomes hydrophobic. Water will bead up or run off instead of soaking in. So, you have to avoid letting it dry out completely. But as long as it stays moist, peat keeps soil wet longer while still allowing air to circulate—ideal for container growing. - Fewer Pathogens and Weed Seeds | Peat is often described as “sterile,” though that’s the gardening use of the word. It’s not sterile in the microbiological sense, but likely contains fewer pathogens and weed seeds than compost or garden soil.
It also provides almost no nutrients—which is fine in a potting mix, where you’re adding fertilizer anyway. You don’t have to account for any nutrient contribution from the peat. - Widely Available & Inexpensive | Peat is easy to find in garden centers and online, and it’s not very expensive. There’s clearly a lot of it being produced and sold.
Put all that together, and it’s no surprise that peat became so widely used. It’s cheap, does what’s needed, and available in potting mix everywhere.
Environmental Awareness
Starting in the 1980s, as we learned more about peatlands and their ecological importance, people began asking more questions about the impact of peat extraction.
Depending on your viewpoint, it may be called peat “harvesting” or “mining” — but either way, it’s extraction.
To extract peat for commercial use, wetlands are drained, and all those layers of peat are removed for processing. If you look up videos, it’s the bog equivalent of clear cutting forests. The end result is a wasteland with little or no remnants of the former ecosystem. Even with improved restoration methods, the degradation caused by peat extraction will continue for decades.
And all that carbon that has been contained for eons is released in the atmosphere.
Carbon Sequestration
Carbon sequestration is a complex topic. Greenhouse gases, particularly carbon dioxide, are essential for life on Earth, but excess contributes to global warming.
Carbon dioxide levels have risen over 30% since 1965, causing rising temperatures and extreme weather events.
We can help counter this by reducing emissions and by storing carbon in “carbon sinks” like soil and plants.
And guess what does an exceptional job as a carbon sink?
Peatlands.
Peatlands store more carbon than all the world’s forests combined
Peatlands are excellent at storing carbon. They store more carbon than all the world’s forests combined. About one-third of all soil carbon is in peatlands, and it got there naturally over thousands of years.
If left undisturbed, peat decomposes slowly and continues to sequester carbon. When we extract peat, that same carbon is—you guessed it—off into the atmosphere where we don’t want it.
Peat Extraction is Not Carbon Neutral
Some argue that composting also releases greenhouse gases—as do many other horticultural practices. And that’s true. Organic matter releases greenhouse gases as it decomposes, and there’s really no way around that.
With compost, the carbon being released was already recently in the atmosphere and is just going back where it was, mostly in the same form. That’s why composting is considered to be nearly carbon-neutral. Peat, on the other hand, contains ancient, sequestered carbon that’s been safely tucked away for millennia.
And the entire extraction process and distribution cycle has its own heavy footprint (which will also be true for many other things we use in the garden).
There’s no disputing that many aspects of the gardening world are hard on the environment. But peat use requires the release of what was and mostly would have remained sequestered carbon. Peat degrades very slowly in peatlands, but once it’s been extracted, the carbon in the peat is released into the air relatively quickly.
What Restoration Really Means
You’ll sometimes hear the soundbite saying (good news!): peatlands can be restored.
Unfortunately, “restoration” after peat extraction doesn’t mean peatlands return to their original state. That doesn’t happen. Restoration just means making them somewhat ecologically functional again, perhaps getting Sphagnum to regrow on part of the land, even if it’s far less than before.
Restoration efforts are better today than in the past but nowhere near what’s needed.
It can take decades for a peat extraction site under restoration to hold more carbon than it emits. And getting back to pre-extraction carbon levels will take centuries — or longer—if ever.
Some restoration attempts fail entirely. A 2013 study found that 43% of sites didn’t return to being Sphagnum-dominated after 10 years.
Plus, restoration often requires donor sites to provide plant material, which causes additional land degradation, disrupting a new area while trying to repair an old one. And many peatland plants won’t grow again on sites after they’ve been restored.
UK & Ireland Versus North America
In the UK and Ireland, about 80% of peatland has been degraded. Across Europe, where peat is a traditional fuel source, it’s about 50% — the highest on any continent.
This issue hasn’t received nearly as much attention in North America.
The U.S. gets 90% of its horticultural peat from Canada, where only about 2% of peatland has been degraded. That sounds promising until you realize this is due to remoteness not restraint.
Much of Canada’s peatland is in arctic or sub-arctic regions or just in remote northern areas where extraction would be too costly. A lot of the peatland is also on Indigenous lands or traditional Indigenous territories where extraction would face vigorous resistance.
The Peat PR Machine
The peat industry has pushed back with PR campaigns, often targeting gardeners with emotional appeals disguised as reasoned argument.
The messaging is selective, downplaying the environmental impact.
I know I used to buy into some of it.
You’ll hear things like: “We have plenty of peat. More is made every year. That means it’s sustainable.”
True sustainability means not using resources in a way that compromises the needs of future generations.
But sustainability isn’t about supply. It’s about preserving peatlands so they can continue to store carbon, manage water, and support biodiversity along with other vital ecological functions. Without them, we’d be living in some apocalyptic ruin.
And sometimes it feels like a race to the bottom. Or an environmental game of chicken.
Sustainability means not satisfying our current needs at the expense of the needs of future generations, and that’s the opposite of what peat extraction does. It’s purely about satisfying current needs and the cost is environmental deterioration that will last for decades and even centuries.
Supporters talking up restoration underplay the difficulty and scale. The restoration they’re referring to is not a return to what was. That credit-card thin layer of moss that might regrow each year cannot undo the damage done. At best, you get a partial, moss-dominated wetland after many, many years. Can we really say that’s restored? And will it matter after that much time?
What About Agriculture?
Peat supporters often point out that agriculture has degraded more peatland than horticulture. And that whataboutism is true. But it doesn’t make horticultural peat extraction any less concerning.
Most agricultural conversions happened decades ago. Horticultural extraction continues today.
For impact, while neither is beneficial, the process for converting peatlands into farmland usually leaves the peat (and carbon) in the ground.
Horticultural extraction, however, removes the peat (and releases the carbon), often digging it out many meters deep. That’s hundreds of thousands of years of accumulation gone.
Summary
Peat has played a major role in potting mixes for the past 70 years—but we now understand the environmental cost is steep. Extracting peat destroys ecosystems. Restoring peatlands can take decades or even centuries, and the carbon released during excavation is hard to justify.
The pending U.K. ban has prompted the development of peat-free alternatives which we’re starting to see here too. Like most changes, it’s imperfect—but a necessary shift toward more responsible practices.
Resources
Read More
- Soil Calculator (Mulch, Compost, & Potting Mix Too)
- How to Fill Tall Raised Beds Without Wasting Soil
- How to Make Leaf Mold (Free Organic Soil Amendment)
- Is Your Soil Well-Draining? Use This Easy Test to Find Out
- Will Pine Needles Make My Soil pH Too Acidic? (No, It’s a Myth)
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~Melissa the Empress of Dirt ♛