Seabrook on ... the need for higher-quality compost

This year John Innes celebrates its centenary with the introduction of a new namesake rose from Peter Beales at the Chelsea Flower Show. We all have reason to thank John Innes for its now well-proven seed and potting compost formulae, to congratulate the firm on its research work over the years and wish it even greater success in the future.

It would be appropriate if the 100th birthday was also celebrated with the sale of centenary John Innes Potting Compost to the original formula - seven parts loam, three parts sphagnum peat and two parts coarse grit. But the current product is quite different. A mechanical analysis of a bag from a well-known manufacturer had six parts peat and peat substitute, one part fine silt and five parts small balls of clay soil, with a few pieces of gravel.

While I could find a few bits of sphagnum, the peat part was mostly composted green waste from the woody pieces, including a piece of wood over 2cm long and 1cm in diameter. What has happened to the fibrous loam from stacked turf sterilised with steam? This product should never carry the illustrious and respected John Innes name.

The story on compost does not end there. Currently giving gardening classes to literally thousands of primary school children with my colleagues Steve and Val Bradley, I am frightened by items we have found in peat-reduced garden potting composts - fragments of glass and three-inch-long twigs of fiercely thorned Pyracantha, for example. Fortunately, so far, composts have been carefully checked over by us and any dangerous pollutants removed. But something needs to be done urgently to return potting composts for gardeners into safe, reliable products.

Composted green waste is fine for soil improvement, but it is black, filthy for youngsters to handle, stains clothes and the heavy weight is a serious disadvantage. Can we not together champion higher-grade materials and promote quality rather than price?

Peter Seabrook is a gardening writer and broadcaster.

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