What’s in the earth in your garden? Do you make your own compost, or buy bags of ‘organic’ growing media from your garden centre? What about potting soil? March and April are busy months for the vegetable gardener, and those of us keen on keeping their gardens organic will probably turn to one of the bags of ‘organic’ growing media available from our local garden centres, especially when seed-planting time comes around. However, their contents may not be quite as…organic…as the printing on them suggests.

New Horizons

‘Organic & Peat Free Compost’ from New Horizons, for example, is a peat-free growing medium that contains composted wood and coir, a material made from coconut palm fibre. Coir is a renewable resource although the distance it has to travel to get here, and the energy involved, calls its use into question. However, unless someone has decided to waste money spraying their coconut palms, it’s organic. Peat is not a renewable resource and its use should therefore be avoided. So far, so good: it’s compost, and it’s peat-free. But what about ‘organic’?

The New Horizons mix varies slightly from year to year as can be seen simply by opening a bag and examining the contents. While the nutrient levels and other factors may not fluctuate, its appearance can be quite different. This year, for example, there are a large number of light-coloured wood chips – more of which a little later.

You are also likely to find flakes of paint, chipboard and fragments of both plastic mouldings and bags. These are hardly organic in terms of gardening standards unless you take the stance that wood products are organic simply because wood comes from trees, and plastic is organic because it comes from crude oil, a naturally-occuring material.

non-compost, image

All these bits of trash - with the exception of the penny, added for scale - came from a bag of so-called 'organic' compost

A spokesperson from the technical department of William Sinclair Horticultural Ltd, the manufacturer of New Horizons, provided the following information:

New Horizons is basically a mix of composted wood and ‘green compost’ which comes from the ‘green bins’ found at recycling centres nationwide. Nutrients, in the form of blood and bone meal, are also added.

The company is aware of the light-coloured wood chips, considers them to be a problem, and has been trying to find some way to darken them. Despite appearances, they say that have all been properly composted. However, they still look and feel pretty much like the wood chips left lying around after a session of log splitting. Composting, as anyone who has made their own can attest, generally breaks down the raw materials involved (garden clippings, kitchen scraps) making them completely unrecognisable, or almost so – but not in this case. Most people, faced with an end result that looked very much like the beginning, might well consider the process to have been incomplete.

Quality control

Every load of materials arriving at William Sinclair is put through a random ‘box test’, and every load of green compost is checked by a laser scanner called ‘Hawkeye’. Suppliers are graded according to an accreditation initiative called ‘PAS100’. This is a voluntary rather than mandatory certification which sets minimum standards for composting, such as the temperature and materials which can be used, and checking for heavy metal levels. It is not specifically organic. If non-compost material is found during the PAS100 check, it is removed and tracked back to the supplier and can therefore count against their PAS100 rating.

So, William Sinclair are clearly doing their utmost to improve the quality of their product. The problem – for us – is that the material supply itself is fatally flawed, as we will see in the next article in this series.

If you enjoyed this post, please leave a comment or subscribe to the RSS feed to have future articles delivered to your feed reader.