Gardening with peat-free compost

Many people do not realise that under the surface of a peat bog there lies a huge store of trapped carbon, which has been created over thousands of years. The water in the bog keeps that carbon in, but as soon as peat begins to drain, for use in compost or for farming, it begins to oxidise and the carbon starts to be released.  So the use of peat in horticulture contributes to two major environmental issues – direct damage to bog environments and the loss of biodiversity, and global heating by the emission of carbon dioxide.

Peatlands are the UK’s largest store of carbon, containing an estimated 3.2 billion tonnes – more than all our forests.  We would be horrified if all these forests were destroyed on our doorstep, yet perhaps because peat bogs are unassuming places, their degradation seems less dramatic.  The UK Governments no longer grant new licences for harvesting peat, but existing production sites will continue to dig peat for years to come.  The reality is that existing peatlands just in England are currently highly degraded and are emitting approx. 11 million tonnes of CO2 equivalents annually, significantly contributing to climate change. The use of peat causes problems by damaging fragile eco-systems and releasing stored carbon, contributing to a changing climate.

All plants, whether grown in media containing peat or alternatives, require the right balance of nutrients, air & water for healthy growth.  Most peat used in UK-sold potting compost is actually imported, mostly from the Republic of Ireland and other EU countries, so until we stop the use of peat altogether, we simply transport the problem abroad, and add to it with transport costs to move the material internationally. The only real solution is to find responsibly sourced alternatives to peat for growing media.

Unfortunately, peat-free growing media are not a like-for-like swap with peat based.  They need different management and getting used to.  Depending on their composition, peat-free potting composts can behave differently but usually they hold more moisture than peat and it can be hard to appreciate how much more.  Good quality peat free composts are also more expensive than peat-based composts, although they can usually be re-used.

There are ways round these things though; some years ago, gardeners had to get used to peat-based composts rather than the loam-based ones which had previously predominated.  Currently peat free growing media may be more expensive and less easy to find in garden centres or online, but because of the environmental problems associated with using peat, it is advisable to do all we can to make the switch.  Also, hopefully, as more people go peat-free, the cost will be driven down.

What does peat-free compost contain?

Research into peat-free potting composts has shown the best results come from a blend of ingredients, eg, coir (a waste product from coconut), wool & bracken (widely available) & wood (wood fibre or composted bark, both of which are renewable and sustainable).  In addition, grit and sharp sand can be in the mix as well as rock wool and perlite, but these last two have a large carbon footprint.

Do’s & Don’ts

Do look for peat-free composts which have a fine, fluffy type texture.  These hold their structure well, meaning they keep a good balance of air and water inside.  Assorted particle sizes within the compost help prevent compaction.

Do check moisture in containers by adding water slowly & carefully.  Stop watering as soon as water starts to seep out of the bottom of the pot.

Do consider making your own compost by using the contents of your bin, perhaps adding grit or sand to change or improve the texture.

Do look carefully at claims on the outside of the packaging.  If it doesn’t say ‘peat-free’ it probably won’t be, even if it says ‘Environmentally Friendly’ or ‘Organic’.

Don’t throw away used compost each year, it can be re-used for planting bulbs; as a mulch; or reinvigorated with organic fertiliser & a top dressing of fresh compost, as long as there is no disease.

Don’t underestimate how much water peat-free compost can hold.  Check before watering to see if the compost really has dried out.  Even if the top part has dried out, it may well be that a centimetre or two down, the compost could be quite moist.

All in all, the three main benefits of going peat-free are carbon storage, flood mitigation and preserving biodiversity, so these are all good reasons to do our best to go green.