Sphagnum Peat Moss – What It Is & How to Use It Wisely In Your Garden

Any gardener knows that the secret to gardening success is your growing medium. Whether you are a conventional gardener or a hydroponic grower, the soil or growing medium needs to provide the plant root systems with;

Good aeration

Good drainage

Enough moisture

And the ability to absorb nutrients.

Peat moss is probably a word you have heard before, but do you actually know what it is and the role it plays in determining the quality of a good compost?

Quite honestly, the first time I used it I thought it was awful stuff because I didn’t know you had to actually soak it first and then use your hands to mulch it up and squeeze out the moisture before you got the lovely spongy, workable end product. Now I can’t live without it!

Traditionally, peat moss has always played a vital role in improving soil. It is a major component in the growing mediums formulated for seedlings, right up to the compost used for transplanting trees and shrubs. It has many practical applications and benefits as well as a few drawbacks.

Let’s look at peat moss in a bit more detail.

What is it exactly?

Why do you need it?

What are the benefits and drawbacks? 

How do you use it?

And where can you buy the perfect peat moss for your plants?

What is Peat Moss And Where Does It Come From?

Peat moss is also known as Sphagnum peat moss. The difference is simple. Peat moss is just dead Sphagnum moss. This primitive plant species known as Sphagnum moss is part of the group of plants known as Bryophytes. These plants bear no seeds or flowers, producing spores instead.

They thrive in moist, shady environments and when the mosses decompose these wetlands turn into peat bogs.  Wet, cold, oxygen poor conditions mean that the presence of bacteria is reduced and plant growth is greater than the rate of decomposition. Over time the dead vegetation turns into peat moss.

Both the living sphagnum and the dead peat mosses are harvested. First the living moss is harvested and then the dead. Sphagnum moss is used differently to sphagnum peat moss as they are very different in appearance and function.

Sphagnum moss is the top of the bog and peat moss is the decomposed product deeper down. Different grades of peat moss are graded using the Von Post Scale for Decomposition, where H2 is the light, spongy formation also known as blonde and H8 is the dark, decomposed, peat that feels like putty. The scale starts at H1 and goes up to H10.

The largest peat bogs are found in Russia with Canada coming in second. Countries like Finland, Sweden, Ireland and Germany also have ideal climatic conditions for bogs to develop.

Why We Need It and How It Works

The Perfect Soil Conditioner

Peat moss is first and foremost a soil conditioner. Soil conditioners repair damaged soil by

loosening compacted soil to improve aeration,

increasing the water holding capacity

and by helping to bond nutrients and water together to help the roots absorb both moisture and food.

The greatest demand for peat moss comes from the horticultural industry but it is used by farmers, landscapers and gardeners alike. It also has important uses in other industries.

Not only is it a porous, fibrous material, it also bears traces of vitamins, polyphenols and humic acid. It has a slightly acid pH and an above average moisture holding capacity. But the nutrients in it are by no means sufficient enough to call peat moss a fertilizer.

It is however a disease suppressant and free of weed seeds. As a soil conditioner and amendment to growing mediums it has many benefits:

Pros and Cons of Using Peat Moss

Pros

1. The pH is slightly acidic. This increases the soil’s buffering capacity, preventing the leaching of fertilizer nutrients. It also means it is ideal for a wide range of acid-loving plants.

2. It loosens clayey soils and compacted soils, improving their porosity, while still keeping its absorbency. Due to the slow decomposition rate, one application can last a long time.

3. Retains water well. It increases the moisture holding capacity in sandy soils, conditioning, increasing absorption rate and raising bioavailabilty of nutrients.

4. It can be added to compost/potting mixes. Because it acts as a soil conditioner it is an important additive to any custom compost/potting mix. A compost/potting soil with peat moss will have a longer lifespan than one just using plain bark chips, for example.

Note: On its own peat moss is just crumbly or powdery dry matter but once soaked and allowed to absorb water it becomes a spongy, workable medium. So make sure to pre-soak before adding to your mix. Pre-mixed composts or other growing mediums already containing peat moss will eventually rehydrate.

5. It is a sterile growing medium. Peat moss is weed and pathogen free. It has disease suppressing qualities against certain root-rot pathogens, making it ideal as a component in hydroponic growing mediums or as a soil amendment to growing mixes like potting soil.

6. It is organic. Used for propagating seedlings both in organic farming and hydroponics.

Note: To make sure you buy peat moss suited to your specific needs, check to see if it is pure and organic or if it has been supplemented with other ingredients or fertilizer, which could kill sensitive carnivorous plants.

7. Increases nutrient relations, known as cation exchange capacity (CEC). This means nutrients in the soil are unlocked and become available to plant through the roots.

8. Compost heaps benefit from added peat moss. What makes peat moss unique is that it has a slower rate of decomposition due to its ability to decompose without oxygen (anaerobic). It won’t rot in wet conditions making it great for adding to compost heaps where you want to lock nutrients in and slow down decomposition.

9. It is readily available.

All these characteristics aid and improve nutrient absorption which in turn helps a plant to grow strong and healthy and produce good quality flowers and fruit.

In today’s world where our soils have been depleted through overuse and erosion, where some soils are just not fertile and friable by nature and where many people live in urban environments where container gardening has to be practised, the use of added compost and substrates like peat moss are essential for growing plants to their full potential.

Cons

1. Harvested from peat bogs. Peatlands are unique eco systems that are home to many endemic species of orchids, shrubs, carnivorous plants and mosses. They play a huge part in reducing greenhouse gases and are rich in carbon. Many birds nest here and mammals and insect hunt and feed in these peat bogs.

2. Considered a non renewable resource. This is a subject of great controversy.

Canada is the main supplier of peat moss for horticultural use while the other countries use it predominantly as a fuel supply. Because of the sensitive subject of whether or not it is ecologically viable to support the peat moss industry I did some thorough research and I have to say, in my humble opinion, I see a lot of effort, money and research has been made, not only to manage it but also to rehabilitate.

NOTE: When buying peat moss, choose a trustworthy, well established company that implements sound harvesting practices and has programmes and initiatives in place that give back to the earth and the community. See my 3 companies of choice down below.

3. Not the cheapest choice: Sourcing a brand that is affordable and of a good standard is paramount. Because there are so many brands out there, often in the past, I have found I’ve paid too much for too little or the quality is sub standard. The trick is to find a brand that is reasonably priced and offers a consistently good grade of peat.

Good Choices: Brands that I have found to be of a consistently high quality, and sourced in a responsible and sustainably renewable manner, are:

Hoffman Canadian Sphagnum Peat Moss – 10qt

Espoma Organic Peat Moss – 8qt

Premier Pro Moss Horticultural Peat Moss 2.2 ft3

For more info on these companies and their peat moss products, scroll down.

How To Use Peat Moss

Peat moss is by no means a stand alone growing medium. It is useful because it can be added to soils, composts, potting mixes and growing mediums. It aerates, retains moisture and lessens soil density, making it a versatile and fundamental ingredient for growing plants successfully.

Listed below are the most common practical applications for peat moss:

Uses for Peat Moss:

Used as a lawn dressing it will correct soil problems like compaction, and it is weed free, making it a good choice. To apply just break up the peat moss to a fine texture, spread it out and rake it evenly over the lawn.

Used when starting lawns from seed, peat moss mixed with topsoil works well. The topsoil holds the roots and the peat moss keeps the seeds and moisture locked in.

In vegetable gardens and raised beds: Add to potting soil and compost mixes by first preparing the peat moss.  A good mix of organic ingredients will give the vegetables the right formula to thrive. Either make a mix from scratch, for tubs, or add a mix to your garden soil and dig it in well.

In compost heaps, peat moss binds nutrients that would normally be lost through the rapid decomposition of the other debris and organic matter in heap. Thanks to its ability to decompose slowly and without oxygen, it keeps in nutrients found deep down in the heap.

Used in primary growing mediums for hydroponics: True hydroponic systems have roots suspended in nutrient solution and the pH of solution is monitored.  With a soil less medium you need to monitor the growing medium as well.

With the increase in popularity of indoor growing, many variations of hydroponic systems have evolved with some using a soilless medium. Peat moss is often used along with other substrates like perlite and vermiculite.

Used in seedling propagation. Ideal for germination when used with a mix of vermiculite, perlite and organic nutrients. Because it is pathogen free it removes the threat of soil borne diseases and reduces damping off.

Used for transplanting trees and shrubs. Mix 1 part peat moss with two parts soil.

Hanging baskets: Often the wire type hanging baskets are lined with straight Sphagnum moss (not peat moss). Not only is it attractive but also holds moisture well.

Specialized plants: Peat moss is the ideal medium for carnivorous plants. It makes perfect potting mixes for African violets when mixed with perlite and vermiculite at a ratio of 2:1:1 (2 parts peat to 1 part perlite and 1 part vermiculite).

Where To Buy the Best Quality Peat Moss:

Peat moss is readily available from most garden centres and retail nurseries. I prefer to shop online as my local stores only stock one or two brands and often the quality and value for money is not so good. The problem with online shopping is you are bombarded with choices and this can be confusing to novice gardeners and growers.

When I’m not busy with my gardens, I spend an unhealthy amount of time “shopping around” online but my efforts have paid off. Here is a list of my top brands. I chose them for certain reasons which I’ll share with you further on.

My Top 3 Peat Moss Products

Hoffman Canadian Sphagnum Peat Moss – 10qt

Espoma Organic Peat Moss – 8qt

Premier Pro Moss Horticultural Peat Moss – 2.5 cu. ft.

Finding The Best: Different Grades and Qualities of Peat Moss

If you have never bought or used peat moss before you will be forgiven for thinking that all peat moss looks and feels the same. In reality, because it is an organic medium, peat moss comes in different grades.

Peat moss is graded by particle size and decomposition rate. The decomposition status is rated by the Von Post Scale of Decomposition.

Some peat moss is very fine and others are much coarser. The coarser types are often used for adding to potting mixes and composts while the finer types are ideal for using in germination mixes or lawn applications.

If using peat moss for hydroponics you can use either type depending on what other substrates you are adding to your growing medium.

Having said all that, buying the finer type is also perfectly okay to add to compost as you will vary the amounts you add to your mix. For example, using the fine peat with pine bark or coco chips as well as adding perlite/vermiculite and lime works well.

The coarser the moss the cheaper it will be as it has been less decomposed but this is not necessarily a bad thing if adding to compost heaps and buying by the bale. The fine stuff may seem more expensive but it is the peat moss that is harvested after the sphagnum has been removed.

If you buy a coarse grain you can reduce it to a finer strain by sieving through a screen. I find it easier just to buy ready to use peat like Premier Pro Moss, especially when I do my lawns once a year.

Top 3 Peat Moss Brands:  Value, Quality and Ethics

Hoffman Canadian Sphagnum Peat Moss – 10qt

Espoma Organic Peat Moss – 8qt

Premier Pro-Moss Horticultural Peat Moss -2.2 cu.ft

All 3 of these companies have built reputable brand names for themselves. Espoma was established in 1929 and Premier Tech Horticulture is listed with the Organic Materials Review Institute (OMRI). Hoffman Canadian Sphagnum Peat Moss is another brand that is very popular and has a good reputation. It is also Canadian sourced.

All three of these brands sell peat moss that guarantees improved soil aeration and water holding capacity. They also say it will to improve drainage in potting mixes and promote root growth. Their peat moss will loosen heavy soils and reduce soil compaction.

Premier Tech has been going since 1923. They promote their Pro Moss Retail Peat Moss for turf maintenance and as a soil amendment for new lawns, thus it comes in a larger quantity. Ideal for gardeners wanting to buy in bulk.

All three can be used for adding to potting mixes and soilless growing mediums.

Espoma sells a range of organic products (also available on Amazon). All are packaged in quantities small enough for the home gardener but affordable enough to buy in quantities if larger amounts are needed.  Most their products are perfect for organic gardening. For custom blends you can buy perlite or vermiculite to add to the peat moss.

Hoffman guarantees their product as being 99.8% organic. This means there may be some kind of preparation they implement before packaging which detracts from being 100% organic but it is still pure peat moss, as is Espoma peat moss and Premium Tech.

Alternatives to Peat Moss

If you are still not convinced that peat moss is the perfect soil conditioner to use or you want to experiment with other amendments you can try the following:

PittMoss Organic Soil Amendment

Coconut coir

Manure

Compost

Pine Needles

Whatever your choices are, when it comes to great gardening just remember the main ingredient is love. And you can’t buy love!

Happy gardening!

Lindsey Hyland grew up in Arizona where she attended University of Arizona’s Controlled Environment Agriculture. She has supplemented her formal education by working on various organic farms, including spending a semester abroad in India. Growing and/or raising just about anything gets her excited. She is especially passionate about environmental justice and low-tech, sustainable ways to better run small-scale farms and homesteads. Lindsey started Urban Organic Yield to discuss gardening tips and tactics.

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