What Is Peat Moss? Alternatives to Peat in the Garden

What Is Peat Moss?

Peat moss or “peat” is made of partially decayed plant material—usually mosses—that have been submerged without oxygen in wet, acidic conditions, like those found in a bog. The decaying process is very slow, taking up to 1,000 years to create a 36-inch layer of it! To harvest or mine it, the bogs are drained, and the peat is scraped off or vacuumed up.

What Is Peat Moss Used For?

Peat moss is a spongy soil amendment that is used in gardening several ways. For example, it’s added to:

1. Seed-starting mixes because it’s lightweight and retains water and nutrients
2. Potting soil used in containers or raised beds as it aides in aeration and keeps soil from drying out
3. Soil used around shrubs and plants that thrive in high acidity, as peat moss will lower the pH in the soil

Is Peat a Renewable Resource?

That’s a question of semantics. While some companies can technically say it’s renewable, we’d say it’s really not in a practical sense. Peat is the result of thousands of years of very particular natural processes and it’s virtually impossible to regenerate and replicate that sensitive habitat. It’s not unreasonable to ask whether it’s worth the destruction of one habitat (a massive carbon dioxide sink) for another (a few species of backyard plants), especially when there are alternatives today.

Peat Depletion in the U.K.

In the UK, peat was used for centuries as heating fuel, and the bogs were drained and harvested mercilessly. Mining it has been incredibly destructive. More recently, commercial interests have taken over the bogs, and the peat is being burned in power plants. These regulated companies are trying to reclaim and replant the bogs, but Ireland has decided to ban the harvesting of peat, and other UK countries are planning to follow suit. 

U.S. Gets Peat From Canada

In North America we get our peat from Canada. The industry there is much younger and operates under strict governmental controls, which require them to replant and restore the water table in the drained areas. There are 280,000,000 acres of peatlands in Canada and about .03% of it has been harvested. Only about .05% of what is harvested goes to horticultural use.

Recreating a natural ecosystem, such as a peat bog that has been destroyed by mining, is like trying to restore an old-growth forest. There are many factors to consider. Along with the mosses, other plants grow there, and the bogs are habitat for many types of birds, amphibians, insects, and mammals. Bogs prevent flooding by soaking up extra water like a sponge, which they then release slowly during times of drought. A drained and dry peat bog can catch fire and burn underground for years, emitting even more carbon!

Alternatives to Peat as a Soil Conditioner

It’s hard not to use peat in some gardening projects. However, there are effective alternatives to using peat as a total soil amendment or conditioner. You can switch to sustainable products such as compost—or aged manure, leaf mold, biochar, cover crops, or green manure. If you need to loosen up your compost, mix in some wood chips, which will aid water and nutrient absorption. A small amount of gravel also works well. We guarantee that quality compost will achieve better results in terms of vigorous growth and more flowering.  

Alternatives to Peat for Potting Soils

In regards to substitutes for peat in potting soil and seed-starting mixtures, a number of different types of fibrous plant materials are being studied for their effectiveness, including 

1. rice hulls,
2. bark,
3. wood fiber,
4. grasses,
5. hemp,
6. paper, and
7. coconut coir. 

A recent research paper ranks pine bark as good as peat moss in seed germination trials!

Coconut Coir as a Peat Substitute

Speaking of coconut coir, a large farm in my area has been using coconut coir as a growing medium for years (Jane Presby of Dimond Hill Farm in Concord, NH). After many years of field growing all her crops, issues with climate change, soil pathogens, sterilizing containers, and weeds made her turn to high tunnels for a more environmentally friendly way to grow crops like tomatoes, eggplant, peppers, and basil.

She found peat to be too inconsistent, sometimes too heavy and wet and other times too light and dry. Now, she uses grow bags filled with fiber dust (very finely ground-up coconut coir pith) in the tunnels and runs driplines into each bag. Since she can plant them closely and train the plants to grow vertically, she reports getting ten times the yield that she got when growing in the field.

She loves the coir. “The roots grow great,” she says. “There are no roadblocks for them.” Coir is a by-product of the coconut industry. Unlike acidic peat, it has a near-neutral pH and is easy to moisten from a dehydrated state. It soaks up seven times its dry weight in water and is very slow to decompose. Hydroponic growers have been using it for years. The downside is that because coconuts are tropical, they are grown mostly in India, Sri Lanka, and the Philippines, so they have a long boat ride to get to North America.

Coir is made from the outer husk of the coconut, which is typically considered a waste product.

Make Your Own Peat-Free Mix

If you would like to try making your own coconut coir-based seed starting mix, here’s an easy recipe:

• 2 parts coconut coir (Use finely ground fiber dust if starting small seeds.)
• 1 part perlite to improve drainage and aid aeration
• 1 part vermiculite to lighten the mix and hold water
• 1 part compost if you wish. It is not necessary, especially if you want the mix to be totally soilless. (We grow our healthiest plants in a compost-based seed starting mix. I think it is the magic ingredient for a happy transplant!)

Whether you choose to phase out peat from your garden or not is up to you, but it is good to know that there are alternatives out there that do the job more sustainably!