5 Reasons To Try Peat-Free Soil Mix This Season

Peat-free soil mixes are becoming more readily available to improve soil health and lessen dependence on a renewable resource. Garden expert Katherine Rowe explores reasons to look for peat-free alternatives to incorporate in seeding, containers, and beds this growing season.

A close-up of dark brown, crumbly material being scooped with a trowel.

Contents

Peat moss is a soil amendment widely used in the gardening industry, from potting mixes for seedlings to large in-ground applications. It’s a natural resource that retains moisture, builds soil structure, reduces runoff, and is weed and pest-free. This amendment is prevalent across garden products, especially in soil (and soil-less) mixes.

Peat has a lot of advantages: it’s natural and multifunctional. However, there are drawbacks to relying on this non-renewable resource. Let’s explore the benefits of lessening our peat reliance in our garden spaces for diverse soil nutrition.

About Peat

Green and yellow strands of fresh Sphagnum moss with visible stems and soft foliage.
Moss is alive at the bog’s surface layer, whereas the low-lying decomposing matter comes from the moss and other plants.

Harvested for centuries, peat serves as a fuel source, insulation, and amendment for agricultural and gardening applications against heavy clay and sandy soils. Peatlands occupy an estimated 2.7% of the earth’s surface. In horticulture, there are two primary types of peat: sphagnum and sedge peat.

Sphagnum peat occurs in specific environments in the northern hemisphere, where sphagnum moss decays in ancient bogs. In North America, most comes from Michigan and Canada, where bogs formed over 10,000 years ago in non-draining depressions, some as glaciers moved across the land. Black spruce and other conifer forests, as well as tundra zones, are common bog sites.

In the bog, dead and decaying organic matter, combined with a lack of oxygen, results in accumulation at the bottom. The muck is acidic and lacks nutrients; when dried in the sun, it turns into the fibrous substance we recognize, sterile and organic.

Sphagnum peat differs from sphagnum moss (the green moss often used in floral or terrarium applications). Moss is alive at the bog’s surface layer, whereas peat is the low-lying decomposing matter from the moss and other plants.

Sedge peat derives from decomposing reeds and sedges in similar boggy environments. The harvest involves removing the upper living layer, harvesting the peat, and replacing the surface. 

Role in Gardening

A small tray filled with dark brown material being watered with a bright green watering can, with plant labels in the tray.
Perhaps the most beneficial aspect is the decayed matter’s capacity to retain water.

As we dive into the benefits of using less peat (and why), it helps to understand its role in our growing setups. A look at the advantages gives an idea of what to look for in an alternative.

Perhaps the most beneficial aspect is the decayed matter’s capacity to retain water. Due to its cellular structure, it quickly absorbs moisture and holds it in place. This keeps water available near roots for easy access.

The decayed moss also helps maintain soil structure and aeration. Mostly due to its moisture retention and fibrous nature, it doesn’t compact or become heavy like other soils and composts. When kept adequately moist, it holds the composition in place. This quality makes it useful in seed starting and seedling growth by supporting developing roots in keeping nutrients and water accessible. Because of its spongy absorption and less compaction, it also reduces runoff.

This amendment is also widely available. It’s an element in many products, from hanging basket liners to seed starting pellets and a lot of potting mixes. Because it’s so readily available, most of us use it at some point, even if we’re unaware. So, to be fully informed in our garden choices, let’s take a look at the benefits of peat-free soil mixes and how to harness similar qualities with alternative components.

Preserving Ecosystem Services

Hands holding a clump of green and yellow moss with attached roots and plant debris.
Harvesting the bogs lessens their living vegetation and carbon sequestration.

Natural bogs are thousands of years in the making. They’re significant carbon stores that absorb and offset emissions. Harvesting the bogs lessens their living vegetation and carbon sequestration, and sourcing the underlayer releases stored carbon dioxide into the atmosphere. 

In addition to acting as carbon sinks, the wetlands also help manage stormwater and prevent localized flooding. The living systems are unique ecosystems for native birds, mammals, amphibians, reptiles, and insects.

There are organizations like the International Peatland Society whose mission is responsible management to address climate change, biodiversity, and restoration. More and more, producers replant bogs post-harvest. Still, it may take 30 to 40 years for a harvested bog to stop producing carbon and centuries for it to recover.

Choosing More Renewable Resources

Brown, fibrous strands of coco coir with a loose, stringy texture.
The most compatible stand-in is coconut coir, which is a fiber from the husks of coconuts.

As gardeners seek peat alternatives, there are increasing options on the market. Reputable companies sell peat-free blends of soil, potting, and seed-starting mixes; check the label to see if the product contains peat or not. At home, compost is among the top alternatives, as is amending with leaf mulch and mold, manure, and bark chips.

The most compatible stand-in is coconut coir. Coco coir is a fiber from the husks of coconuts. Coir’s fibrous texture retains moisture and contributes to light, porous soils. 

While coir is a renewable resource, it does carry a carbon footprint in traveling distances and in production, mostly from India and Sri Lanka. It’s also not nutrient-rich, which is another commonality it shares with peat. 

Less Drying and Soil Cracking

A close-up of dry, cracked brown surface with irregular patterns and deep fissures.
As the amendment dries, soils can dry and crack.

A disadvantage of peat is its hydrophobic tendencies. While it holds water, when it dries out, it repels water. It takes deep watering to re-saturate it completely. Dry spells can lead to root stress as moisture isn’t available without a good soak or repeated soaking to reactivate water-holding capacity.

As the amendment dries, soils can dry and crack. This makes conditions like dry clay soils worse, as both materials take concentrated water to rehydrate. The initial water runs off until soils are able to retain moisture. Using a peat-free soil mix may not experience the same dehydration issues during dry spells or underwatering.

Get More Nutrient-Rich Amendments

A gloved hand holds loose, crumbly brown material while pouring it into a container, set against a backdrop of green foliage and a wooden garden surface.
Using compost-based amendments like green material or worm castings to add nutrition and enrich soils.

Due to its lack of oxygen in decomposition, peat lacks nutrients. It doesn’t offer soil enrichment or benefits for microbes. Using compost-based amendments like green material or worm castings to add nutrition and enrich soils. Compost in alternative formulas can be plant-based, manure, or worm castings—whatever your preference or at-home system. It needs to be completely broken down and sterilized. 

Compost can become compact, dense, and decompose faster than peat and should be balanced with native soils and lighter particulates. For conditions like seeding and potting, sift it to remove large pieces. Chunky soil or compost can create air pockets or impediments for new roots.

A peat-free mix with compost is not as acidic, which is an advantage for plants that prefer neutral or alkaline soils. While peat acidity usually fades, it can spike initially, causing a lower pH at planting.

Make Your Own Potting Mix: Peat-Free Recipes

Hands holding dark brown, chunky bark pieces with a mix of fine and coarse textures.
Experiment with compost and aged bark, wood chips, or leaf mold as coir substitutes or additional amendments.

Peat-free potting mixes can be less expensive, and buying one ready-to-go takes the guesswork out of viable substitutes. But making your own goes a long way with materials that have versatile uses for seedlings, edibles, and ornamentals.

Experiment with compost and aged bark, wood chips, or leaf mold as coir substitutes or additional amendments. For fertilizers, adjust your ration depending on the amount of your overall mix. You don’t want to add a full cup of fertilizer to an overall 5-gallon volume, as it will be too much.

Seeds and Seedlings:

  • 1 part compost
  • 1 part coco coir (rehydrated if in dry blocks, before measuring)
  • 1 part coarse sand or perlite
  • 1 cup fertilizer (alfalfa meal, kelp, fish emulsion, bone meal, blood meal, or greensand)

Edible Mix:

  • 2 parts compost or peat-free garden soil
  • 2 parts coco coir
  • 1 part sand
  • 1 cup fertilizer of choice (above)

For Ornamentals:

  • 1 part compost
  • 1 part coco coir
  • 1 part peat-free garden soil
  • 1 part sand or perlite
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