Brian Minter: Uncovering the myths around peat moss

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In the current world of horticulture, whether it be large commercial productions or small space container gardens, there’s a perception that we should not be using peat moss as a growing media.

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We hear things like there’s a limited supply, and it’s not sustainable. We’re also led to believe that peat harvesting is destroying habitat which cannot be replenished.

Of course, all natural resources should be used in a sustainable manner. ‘Less is more’ is the operative term upon which we need to focus. We also need to be aware of the environmental impact of all the products we use. In Canada, peat harvesting is highly regulated and very strict environmental regulations must be followed.

I recently listened to a webinar presented by Susan Parent, a biologist based in Montreal. She is employed by Premier Tech, one of Canada’s leading manufacturers of lawn and garden products. This company is nearly 100 years old and has been, along with other businesses, harvesting peat moss for 90 of those years. I also spoke with her to get further clarification on some important related issues.

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I realize that her perspective is based on her company’s harvesting and sales of peat moss, but she provided some valuable insights and statistics on the state of peat in Canada.

According to Parent, Canada has, by far, the largest number of peat bogs in the world. In these bogs, the natural accumulation of new peat is in the range of 20 million tons each year. Of this amount, 1.38 million tons of peat is harvested annually. Canada’s peat bogs represent 113.6 million hectares, of which only 0.03 per cent has been harvested for horticultural uses.

Of this total area, the approximate breakdown of usage is as follows:

• 81 per cent remains virgin sites;

• Agriculture uses 15 per cent;

• Urban development encroaches on 0.8 per cent;

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• Reservoirs take up 0.8 per cent;

• Miscellaneous development accounts for 0.71 per cent;

• Ports use 0.3 per cent; forestry 0.02 per cent; and harvesting 0.03 per cent.

Parent pointed out that peat provides three essential elements for plants. It retains water up to 20 times its weight; it has great nutrient retention; and ironically, it also provides natural aeration and porosity to improve drainage.

Peat is pest and weed free and is approved for organic production. It combines well with other materials, like coco coir, sawdust, bark mulch, rice hulls and processed organic matter. Depending on the crop, materials, like pumice, perlite and sand, are added to peat to both satisfy the crop’s requirements and to use less peat.

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Increased high-density food production will be vital to provide more food for an ever-increasing world population. Growing media of all types will be required in greater quantities, and peat is just one of those options. Parent pointed out that food security will be an important issue when it comes to the use of peat moss.

I asked her about the long-term sustainability of our Canadian peat bogs. She is very proud of the fact that the peat moss industry did not wait for the government to provide regulation, but rather the industry developed and managed its own sustainability programs.

As I mentioned earlier, of the roughly 114 million hectares of peat bogs in Canada, only 32,000 hectares have been harvested. This is, according to Parent, 1/6000th or 0.03 per cent of the resource. Over the next few years, 18,000 hectares are slated to be harvested. Harvesting has ceased on 4,200 hectares, and since 2017, 4,800 hectares have either been restored or are in the process of being restored.

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It was very interesting to learn that when peat is harvested by a vacuum method, it can be done only in summer when the peat is dry. So, harvesting takes place over a 30-to-40-day period. If the weather is rainy or windy, harvesting must stop. If there’s a peat moss shortage, it’s because of fewer harvest days. To ensure that the bogs can be restored, harvesters remove peat only to a depth of two to three feet.

Restitution, she said, is a multi-step process. First, they must level the area and then raise the water table to its original height. Next, they replant with varieties of low-growing sphagnums and other indigenous plants, like native blueberries and rhododendrons. Finally, they protect the new plantings with mulch and hay to assist new growth.

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From an environmental standpoint, peat bogs sequester a great deal of carbon, and I was curious to know how long it takes for a restored bog to act as a carbon sink. Parent said it takes about six years for the regrowth to bring the bog back to its productive state and for carbon sequestering to begin.

Veriflora, a U.S. based, not-for-profit environmental certification entity, consistently checks all the harvesting and restoration activities to ensure they are conforming to environmental best practices.

I asked Parent for her assessment of the current demand for peat. Is it stable or increasing?

“The demand is always strong,” she said, “but from my perspective, there is a modest increase in sales. So much depends on the amount that can be harvested in a limited time frame.”

On such an important subject, it’s good to get some insight on the sustainability of this unique natural resource. It is also reassuring to know that using peat moss in moderation, by itself or in soilless mixes, is an ethically and environmentally responsible practice. So too is working back into our gardens and compost any used soils, removed from patio pots and raised beds, that contain peat moss.