Organic Composts Are Made Without Synthetic Chemicals – How You Can Make Your Own
Elizabeth is a Permaculture Garden Designer, Sustainability Consultant and Professional Writer, working as an advocate for positive change. She graduated from the University of St. Andrews with an MA in English and Philosophy and obtained a Diploma in Applied Permaculture Design from the Permaculture Association.
Reviewed By PETER LICKORISH
Peter is a Horticulture Lecturer and self-employed Horticulturist, with a passion for diverse areas of the industry - from garden design to the science behind plant growth and propagation. He has completed the Royal Horticultural Society’s Master of Horticulture (MHort) Award and lectures on RHS courses at Bedford College.
Contributions From THE 3 GROWBAGS
What started as a blog turned into a huge project and an online shop for sisters Elaine, Caroline and Laura, who make up The 3 Growbags. They frequently document their journey and have made appearances at several RHS shows. All three are full members of the Garden Media Guild.
IN THIS GUIDE
The term ‘organic’ can be a confusing one.
The term is sometimes used to describe anything of, relating to or derived from natural living things.
This is the definition we use when we talk, for example, about adding organic matter to the soil in our gardens.
What Is Organic Compost?
Organic composts are any composts (or potting mixes) that do not contain any synthetic fertilisers, and which contain ingredients grown organically.
And they may also be (though are not necessarily) free from peat, since though peat is a natural material, extracting it for garden use is hugely damaging to the environment.1Environmental experts call on retailers to end sale of climate-harming compost. (n.d.). Sustain. Retrieved March 21, 2023, from https://www.sustainweb.org/news/jun21-sustain-calls-for-ban-of-peat-free-compost/
However, when it comes to buying compost, we are using the term ‘organic’ in a narrower sense.
An organic product is a product that is grown/made without the use of man-made fertilisers, pesticides, herbicides or other harmful chemicals.
Holistic organic production, however, also involves a systems approach that works towards environmentally, socially and economically responsible production.
“When choosing a compost, sustainability should be at the forefront of any decision,” shares Master Horticulturist Peter Lickorish.
“This may include how compost is packaged. Buying one larger bag will involve less plastic use than two small bags, though be careful when handling large bags of compost.
“Some bags are recyclable through plastic collections, such as at garden centres. You could repurpose compost bags to line hanging baskets or for growing potatoes.
“Buying a block of coir, which can be hydrated to a much larger size for use at home, saves on transport emissions.
“Even though it is not grown locally, its lightweight nature means it can have a lower carbon footprint for transport than other materials. Remember to check that the coir is organic.”
Of course, the easiest and cheapest way to get your hands on some organic compost is to make your own in your garden.
Homemade compost is the most eco-friendly and sustainable choice of all.2Cathey, A., & Ashrap, P. (2019, September 19). Trash to Treasure: The Incredible Benefits of Composting. The Regents of the University of Michigan. Retrieved March 21, 2023, from https://sph.umich.edu/pursuit/2019posts/benefits-of-composting.html
Since you make it yourself, you will know exactly what has gone into it, and will have ultimate control over the credentials (and quality) of the product.
However, there may sometimes be times when you cannot make enough, or cannot do so quickly enough. In which case, buying organic compost is the next best choice, environmentally speaking.
Buying organic compost that is free from harmful chemicals, and peat-free, is a far better choice than selecting other forms of compost, which will pose a threat to the environment.
Though it is important to work out whether you want a true compost, or are actually looking for an organic potting mix, as these are two different things.
What Is It Made Of?
Organic compost can be made up of a range of different materials.
If you are making your own organic compost then of course it will be made up of all the different ingredients that you added to your composting system.
It will contain both brown (carbon-rich) and green (nitrogen-rich) materials.
If you purchase an organic compost, it will usually be either a soil-improving compost comparable to a homemade compost, or a potting mix.
Which one you will choose will depend on how exactly you wish to use it in your garden.
Organic potting mix is usually a soil-free mix, which includes a proportion of composted waste, mixed in with a substrate of other peat-free materials.
Organic composts or potting mixes can be purchased which have a range of different ingredients and formulations.
Some, for example, are made from a mix of composted forest or garden cuttings – or organic green waste such as composted bark fines, coconut husk, bracken, wool etc.
Of course, whichever ingredients go into the blend, these are organic in origin.
Though organic composts do not contain the synthetic fertilisers that are added to some other composts on the market, the blends have been carefully worked out to ensure good fertility and good plant growth and so results are now comparable with other non-organic options on the market.
How To Make Organic Compost
There are a number of ways to make your own organic compost at home.
You can compost in place in a no dig gardening system, or set up a simple cold composting heap or bin.
You can also speed up decomposition by aerating the mix (with a compost tumbler, for example), by enlisting the help of special worms (and setting up a vermicomposting system), by increasing temperatures (and making a hot composting system) or by using bokashi systems (and fermenting scraps prior to composting).
Of course, whichever composting method or methods you choose, it will only be organic (in the narrower sense) if you garden organically and none of the ingredients you add are contaminated with pesticides, synthetic fertilisers or other harmful substances.
“When I make compost at home, I aim for around 60% finely chopped brown carbon material and 40% green material,” says Peter.
“The mix may vary to control moisture, such as whether cardboard is used, which can soak up water, or twigs, which aid aeration.”
If you want to create your own potting mix, you can do so by combining this sort of homemade organic compost with other ingredients.
You can increase the density of your potting mix by combining homemade compost with loam or garden soil.
The added weight may make tall pots more stable, but the potting mix may slump over time.
Adding leaf mould or other ingredients can reduce density and create a more friable, aerated mix.
Organic Compost Vs Potting Soil
An organic compost is used to add fertility to growing areas and improve the soil.
It is an essential ingredient in organic gardening.
Organic compost can be used as the top layer for new no dig garden beds, and spread as mulch around your plants.
An organic potting mix is formulated specifically for starting seeds, and growing on plants in pots.
It is also a medium designed to promote healthy growth for plants grown in containers.
Typically lower in nutrients, but with a better texture for water retention/ drainage and aeration, a potting mix will usually also require the addition of organic fertilisers throughout the growing season.
“With the cost of compost, I always recycle my old pot compost by adding in a bit of organic matter grit and slow release fertiliser,” says Laura from The 3 Growbags.
“However, this can lead to a problem with weeds, so I just put a surface layer of bought (so sterile) compost to finish off the new planting and stop the light from getting through to trigger the germination of the weeds.”
Where Can I Buy Truly Organic Compost?
Organic compost or organic potting soil is increasingly being offered as an option in garden centres and plant nurseries.
However, you may find it easier to find organic options online.
Here are a few great options:
- Dalefoot Composts (Certified Organic by the Soil Association)3Dalefoot Composts | Peat Free Compost. (n.d.). Dalefoot Composts. Retrieved March 21, 2023, from https://www.dalefootcomposts.co.uk/
- Fertile Fibre (Certified Organic by the Soil Association)4Organic Compost – Buy Organic Compost Online for UK Delivery. (n.d.). The Fertile Fibre Company. Retrieved March 21, 2023, from https://www.fertilefibre.com/collections/organic
- Moorland Gold (Certified Organic by the Soil Association)
One other recommended sustainable option, though not completely certified organic in origin is:
Melcourt Sylvagrow Sustainable Growing Medium (Endorsed by the RHS).5Melcourt Ltd. (2023, January 18). SylvaGrow® Multi-Purpose. Melcourt. Retrieved March 21, 2023, from https://melcourt.co.uk/products/sylvagrow-multi-purpose/
