November 2013 Newsletter (vol.23)   >>   The Peat Debate



What growing media(s) do you use? Have you used the same brand for years or have you recently switched? Pro-Mix, Fafard, Sunshine, etc are all brands of soilless mixes that may seem exactly the same, but are different in many ways. All of the brands listed above make different types of soilless mixes; some for germinating seeds, growing trees, using in flats or using for perennials in gallon containers. While you may not know the exact percentages of the ingredients, I bet you do know who the manufacturer is. Also, I bet you have done some experimenting as to which manufacturer and which specific type you like best, based on water holding capacity, ease of working with, price, etc. Once you find something that you like it might be hard to switch, but have you ever thought about using a media that does not contain peat?


Peat has been the long time base for most soilless mixes for years. It has the correct properties that many people like in their soilless mixes. However, peat comes from peat bogs and most of the peat that we use or sell is from Canada. These bogs have been around for thousands of years, since the last ice age, to be exact. They represent only 25% of the peat bogs of the world while the other 75% is located in Russia, northern Europe, and some in South America. A growing debate in the horticulture industry is the belief that we are consuming too much of the peat bogs. The question is, are we truly using too much of our resources yearly or is there plenty of supply? There are over 270 million acres of peat lands in Canada and harvesting has only been done on less than 40,000 acres with less than 3,000 acres completed. The harvesting season usually runs April through October with about 40 to 50 days that are acceptable harvesting days dues to the weather restrictions. The argument for many people is that peat is not a renewable source for the horticulture industry and we need to find a better more renewable source. The peat bogs do reproduce but it is at a very slow rate per year. During harvest the company can remove more in 1 day from a bog then what will be able to grow in 5 plus years in the same surface area.


One of the options has recently come on the market in the USA is a natural product called coir. This is a byproduct of ground up coconut husk. Chunks of coir were first used to grow orchids, ferns and other tropical plants. For decades, tropical regions have been adding the finer particles into soilless mixes. It has been shown in many studies that peat can be replaced with coir on a 1 to 1 ratio. Coir even has a few benefits that peat does not. It can absorb water much quicker and easier. It is also closer to the ideal pH compared to peat. On the flip side peat does have a few advantages. Peat has a tried and proven record with many growers. Coir also may be more expensive to add to your mix due to the transportation cost of coming from tropical regions. The high level of salt in the coir products comes from the cleaning of the husk of the coconuts. Since coconuts are from tropical regions they clean the husk with salt water. To ensure that your coir does not have this problem make sure you are getting it from a reputable company and has been treated (the removal of excess salts). Because coconuts are produced and harvested each year, coir is being called a renewable resource, thus making the debate more interesting.


Another option that has been used is bark. Bark has been added to many heavy weight mixes in the years past. It is a great choice if you want to add more air porosity and achieve better drainage. Adding bark into your mix it will probably decrease the cost of your soilless mix as well. These mixes are best if used for woody ornamentals, perennials, flats, etc. There have been studies done that show that it helps decrease the amount of damping off that occurs. However, it might not be the best option for seed starting or hanging baskets since it adds weight to the mixes. While bark cannot be a direct alternative to peat, it can help to decrease the amount of peat used in a soilless mix. It is possible to reduce the peat used by at least 20%-30% or even more. The best type of bark to be used for this is processed pine however, there are other types being used, such as fir and hemlock barks. While bark is readily available in the USA as a byproduct of harvesting trees, it cannot be used as a total replacement of peat.


After hearing some of the alternatives to using peat in your soilless mixes it is important to be an informed consumer and hear all sides of the debate. Large manufacturers of soilless media have come out and said that peat IS a renewable source for the industry. They have said that there should be no concern with the use of peat moss as the base of the growing media industry in North America. The resource is huge, the amount of extraction is small by comparison and the industry and government are committed to sustainable development. They have gone on to say that peat is growing 50 to 70 times faster than it is being harvested. Most, if not all, of the companies that harvest peat from the bogs leave at least 3 inches if not more at the bottom of the bog, so the bog can reproduce and create more peat. These companies have also started making new types of soilless mixes that include other ingredients, like bark and coir, to meet the demand of the consumer and to expand the options.


The peat debate continues as to whether we are using too much peat for the horticulture industry too fast. The heated discussions will continue for years, if not decades into the future. People are trying to come up with alternatives that are cost effective as well as acceptable by the growers like you. They have come up with a few options so far, like bark and coir, but many people are not convinced that we need an alternative for peat. All in all it is up to the grower and the industry as to what will be acceptable and if and when to find an alternative. The choice is yours!



Adding Screened Bark to Potting mix:


Soilless Substrate Management:


Getting to the Coir of the Matter:


Tips for best use of Coir:


Sun Gro Horticulture Peat Moss Industry: