Have you noticed how peat moss is everywhere? Giant bales tower at nurseries and garden centers. Pick up a bag of potting mix and peat moss is usually a main ingredient. You will see it in seed-starting mixtures too. But peat moss is environmentally problematic and not so great for your garden. Here’s why.
Why I Don’t Recommend Peat Moss for Your Garden
Peat moss is often recommended to gardeners because it is organic matter that can help lighten soils. But these benefits come with several costs.
- Peat moss is low in nutrients.
- People often profess peat moss’ ability to hold lots of water. And it can once it is wet. But getting peat wet is tricky because dry peat moss will actually repel water. Perhaps you have noticed this if you ever tried to mix water and peat moss. It is a difficult task, though they will eventually combine in time. I haven’t seen any studies on this, but common sense tells me that it is not a good idea to put something in your garden beds that could resist water. If it has been dry and you get a quick rainstorm, the peat will likely repel the water. It could mean a dryer bed and less water for your plants. For this reason too, you don’t want to use peat moss as a mulch, as the water will run off and not percolate down into your plants. (To counteract this problem, potting soil companies add wetting agents to their soil mixes so the peat is more likely to absorb the water.)
- Peat moss is acidic (pH is about 4.4) and could stress plants that don’t like acid soil (most plants). If you are growing “acid-loving” plants, such as blueberries, first take a soil pH test. If you would like the soil to become more acidic, try adding shredded oak leaves or pine needles. Seek out other ways to acidify the soil.
- Earthworms don’t care for peat moss. Since peat is low in nutrients, microorganisms, possibly dry, and has an acidic pH, the earthworms are likely to seek other food sources. We need to encourage earthworms in our gardens–not discourage them. They are great for our gardens, aerating and loosening soil, and fertilizing with their casts.
- There is some evidence that breathing in peat dust can cause problems for humans and dogs.
For a beautiful, successful garden, adding organic matter is really important. But a better alternative to peat moss in your garden beds is compost. Compost will improve soil structure, provide nutritious organic matter, and hold on to water for your plants. Earthworms also love it. Compost can also be used as a mulch. And if you make your own it is free.
Problems with Peat and the Environment
For me, the environmental costs of peat are a deal breaker.
Peat moss is mostly decomposed sphagnum moss, found and mined from peat bogs. These bogs are their own ecosystems, complete with flora and fauna, containing a tremendous amount of biodiversity. When the peat moss is dug from the site, this ecosystem is severely altered or destroyed.
Manufactures of peat moss often claim that their product is sustainable because peat bogs are restorable. But creating a peat bog is a slow process. It takes several centuries, even thousands of years, for a peat bog to develop and accumulate peat. (Moss decomposition happens very slowly because the bogs are wet, displacing any oxygen.) Removing peat is not sustainable in my book.
Even more dramatic are the effects on climate change. That’s right, peat bogs affect climate change. It turns out that peat bogs store huge amounts of carbon–storing on average 10 times more carbon per hectare than other ecosystems (even more than tropical rainforests.) Worldwide peat bogs store an estimated 500 billion metric tons of carbon (roughly 1,450 metric tons of carbon per hectare). When they drain a peat bog, carbon releases into the atmosphere. The mining of the peat moss further releases more carbon. As we know, greater amounts of carbon in the atmosphere contribute to greater warming, and thus climate change.
Climate scientists now see rewetting dry peatlands and leaving peatlands intact as an important part of slowing the release of carbon dioxide into the atmosphere.
Additionally, harvesting peat moss is an extremely mechanized process that uses fossil fuel energy. Large machines drain, scrape, vacuum, dig up, and cut the peat moss. Once packaged in plastic, the peat travels thousands of miles. (Most of the peat moss sold in the United States comes from Canada.)
We can do better.
Alternatives to Peat Moss
I have already mentioned how compost is a great alternative to peat moss in your yard and garden beds.
Coconut coir, the leftover remains of coconuts, makes a good replacement for peat moss in potting soils, seed-starting mixtures, and containers. Coconut coir is sustainable (though admittedly, like peat moss, coir comes from far places). I recently sowed this year’s seeds in Eco-co® Coir Seed Starting Mix by Gardener’s Supply Company. It is sterile like peat moss and comes as a small brick; you add warm water, and it expands to about 10 quarts. I liked how light it was, and it smelled like earth. So far so good.
I have also used coconut coir planting pots instead of peat pots with success. The 3″ size is big enough to support good growth and good moisture levels for the seedlings. They biodegrade in the soil once planted.
Read labels and avoid products that contain peat, peat moss, or moss.
So this gardening season, skip the peat. You can still have a great garden without it.