Horticulture Magazine

Peat-Free Compost

propagation of succulent leaf cuttings in peat-free compost

What Is Peat-Free Compost?

Peat free compost, as the name suggests, is any compost that does not contain peat. Peat is a natural accumulation of partially decayed vegetation or organic matter. It is found in areas of peatland, bogs, moors and mires.

Peat has traditionally been used to creating potting composts because it has a range of benefits for growing plants. However, those who are environmentally conscious have recognised that digging up precious peat ecosystems to grow our plants is not a sustainable or eco-friendly choice.

Consumers and compost manufacturers, therefore, are increasingly turning to alternative options – these peat-free composts were historically considered to be inferior to peat-based products for potting mixes. But research and development has now generated a range of products that can be as good as, or even superior to peat-based options.

Gardeners can either make their own peat-free composts and potting mixes, or purchase a product that states that it is peat free on the label. Either way, watering and feeding requirements will usually be somewhat different for peat-free growing media than for peat-based options.

One important thing to note about peat-free composts is that they can vary significantly in their ingredients and efficacy. Some are much better than others. Typically, price is indicative of how good a peat free compost will be. The results of using a cheaper peat-free compost option will usually be more variable, and if you pay a little more, you will tend to see better results.

Do not be tricked by terms on a label such as ‘organic’ or ‘eco friendly’ – such wording does not always guarantee that a compost or potting mix is peat-free.

What Is It Made Of?

Peat free composts and potting mixes can be made using a range of different ingredients, to a range of different recipes.

Most peat-free options contain one or more of the following:

  • Woody materials (bark, woodfibre, sawdust, etc..)
  • Coconut husk (coir)
  • Municipal green waste (usually no more than 30% of the finished product).
  • Bracken
  • Straw waste
  • Waste sheep’s wool.

A home made growing medium usually comprises:

  • Homemade compost (made with brown carbon rich and green nitrogen rich materials).
  • Leaf mold
  • Loam/ sand (inorganic soil elements)

What Are Its Benefits?

A peat free growing medium is far better for our planet. Using peat simply isn’t an option for anyone who wants to garden in a sustainable and eco-friendly way.

Peat comes primarily from lowland raised bogs, which is an increasingly rare habitat type in the UK and across Europe.

Peat bogs are important wetlands, which play a vital role in the water cycle, flood mitigation, and in drinking water provision and filtration. In the UK, more than 28 million people use drinking water from water sources that rely on peatlands. And globally, peatlands provide nearly 4% of all potable water stored in reservoirs.

The distinctive environmental conditions of peat wetlands mean that they provide a crucial habitat for a wide range of flora and fauna. Preserving wetlands is crucial for preserving biodiversity and halting biodiversity losses. Wetlands are the most biologically diverse of all ecosystems, and it is vital that we protect these precious ecosystems.

What is more, protecting peatlands is also crucial for carbon sequestration. Peatland ecosystems store more CO2 than all other vegetation types, including the world’s forests. Peat covers just 3% of the world’s land area, but stores 1/3 of the Earth’s soil carbon.

When we dig up peat for use in horticulture, we are hastening the destruction of these precious ecosystems. And contributing to the climate crisis. The problem is that while peat is naturally replenished, it only grows very slowly (around 1mm per year). We are using it up far faster than it can naturally be replaced.

Peat free growing media can be a far more sustainable and eco-friendly choice. Though it is important to look into exactly what goes into a peat-free compost, and where it comes from.

When choosing a peat free compost, we need to look at issues such as water retention, water distribution and nutrient provision. We need to balance our own needs and the needs of our plants with the needs of the planet and humanity as a whole to make the right compost choices for our gardens.

What Do You Use Peat Free Compost For?

Peat free composts vary considerably. Some are considered to be all-purpose composts, which can be used for a wide range of different plants through all stages of their growth. Some are specifically suited to seed starting, or for growing in containers. Others are specifically suited to ericaceous (acid-loving) plants.

Make sure you pay attention to what exactly is in a peat free compost, and read about the plants to which it is suited.

Wood based mixes tend to be suitable for most plants, as they have excellent drainage properties and low pH. Coir retains water well, and maintains good aeration, but does not hold nutrients well. Green waste, where this is used, has high levels of nutrients. But has high pH and may not always be the best option for seed starting and potting mixes. Bracken is high in  potash, and sheep’s wool provides slow release nitrogen and is good for water retention.

Make sure that you choose (or create) a potting mix suited to the plants you wish to grow.

How To Make Peat-Free Compost

It is perfectly possible to make your own peat-free compost/ potting mix. There are a number of different recipes to consider, which combine a compost made at home with organic matter with leaf mould, and soil ingredients like loam/sand.

If you do decide to make your own then of course the results can be variable. One issue is that if you use a soil component, weeds and fungal pathogens can creep in. Personally, I have had few issues with using a mix of 1/3 compost (including well rotted chicken manure and bedding as well as kitchen scraps, and shredded woody material from the garden), 1/3 leaf mould and 1/3 loamy soil to start my seeds.

If you have issues with damping off when sowing seeds into this mix, you can sterilize the loam/soil using your oven. PH, moisture retention and available nutrients will be variable. But good composting practices can help you to establish a successful system and make a potting mix that works for a wide range of edible produce and other plants.

You can also choose a soil-less recipe, and use woody materials or coir to create the right mix. Though coir is a waste product, however, it is worth noting that it may not be the most eco-friendly choice either, since it has to travel a long way to reach us.

Frequently Asked Questions

Is Peat Free Compost Good For Vegetables?

A peat free compost can be excellent for growing vegetables in your garden, whether you use it as a top layer for a no dig garden bed, as a mulch around your growing plants. Some peat free composts can also be useful to fill containers for sowing seeds and growing vegetables in pots.

However, it is worth noting that depending on its makeup and ingredients, a peat free compost may require you to employ different watering habits than if you used peat-based media.

You may also have to think about adding additional nutrients. Different peat free formulations have different balances of nitrogen, phosphorus and potassium, and other nutrients required for good plant growth. Other organic mulches, companion planting, organic fertilizer pellets and organic liquid plant feeds are all ways to add nutrients in an organic garden.

Is It Good For Carnivorous Plants?

Carnivorous plants naturally come from peaty, boggy environments. So you might imagine that a peat-based medium is required to grow these plants. However, it is (fortunately) not essential to destroy these plants’ natural environments in order to grow them in pots.

Not all peat-free composts are suitable for growing these plants. Many commercially available mixes will not suit at all, and some will yield variable results.

But the key to growing these plants successfully lies in replicating the core ideas of their native environment – not necessarily in replicating the conditions exactly. You can replicate the conditions with peat free alternatives such as a mix of Melcourt Growbark pine, perlite and lime-free grit, for example. Fertile fibre coir and perlite is another mix reported to have worked. Sylvagrow peat free compost is another mix that carnivorous plant growers have reported as yielding good results.

If you decide that you must opt for peat, at least go for a reduced peat option, or better yet, Moorland Gold which uses peat from rivers and dams rather than peat that has been dug up from its natural environment.

Do Vine Weevil Live In Peat-Free Soil?

Vine weevils are a common garden pest. Adults will feed on foliage, through will not usually kill your plants. However, these do most damage during the larval stage, when they feed on plant roots during spring and autumn. If enough root feeding takes place, plants can wither and die.

Both peat based and peat free composts improve soil structure, which unfortunately creates a more ideal environment for vine weevil larvae in the soil or growing medium.

Whenever buying in compost (or plants) make sure you choose only options that come from a reputable source, so you do not introduce these pests into your garden.

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