Ask Leo: what is the greenest alternative to compost containing peat?

I know that I should avoid compost containing peat, but what is the most environmentally friendly alternative that I can buy?
R Townsend, by email

This article originally appeared in The Guardian

After years of campaigning by environmental NGOs and celebrity gardeners, the penny has finally dropped that peat-based compost is a no-no due to the devastation its extraction can cause in areas such as lowland raised bogs. But gardeners are now wondering what they should be using instead. The obvious answer is to turn your hand to home composting. Yet the majority of us will still pop down to the garden centre to load up with bagfuls of prepared compost. This is because what we can make ourselves at home is considered a soil improver, not a potting compost per se.

Many retailers have now pledged to reduce or eliminate the use of peat-based composts and have introduced ranges of "eco-friendly" compost. The Royal Horticultural Society says most peat-free composts and grow-bags contain a range of organic materials including composted or chipped bark from the timber industry, coir fibre (coconut husk), wood fibre (sawdust, shredded paper) and the material our councils collect from our doorstep as "green garden waste" (once treated, this can usually be bought direct from the local contractor - ask your council). Inorganic materials are added to improve the structure, including grit, sharp sand, rock wool and perlite. But the RHS says finding peat-free ericaceous compost for acid-loving plants is still hard, which is why you still see the unsatisfactory "peat-reduced" label. It also adds a warning about buying compost: "If the bag doesn't say peat-free, it most likely isn't. Wording such as 'environmentally friendly' and 'organic' can confuse gardeners into thinking they are buying peat-free products."

But labelling regulation for compost is incredibly lax. We have no real way of knowing exactly what is in it. For example, green waste collected by councils could contain high doses of weedkiller, which can make its way into the compost we buy. Equally, there's no way of knowing the quality of the farmyard manure added to some composts. As some form of safeguard, you can try looking out for Soil Association-certified compost.

This article originally appeared in The Guardian

This article first appeared in the Ecologist April 2009

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