Compost quality makes big difference (From Darlington and Stockton Times)

Compost quality makes big difference

12:05pm Friday 5th February 2010

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THERE is still huge disparity between the quality of different composts on the market, according to new research.

Gardeners may be wasting their money on products which produce small, sickly looking plants, according to trials by Which? Gardening.

B&Q Multipurpose, B&Q Sowing and Cutting composts and consistent performer New Horizon Organic and Peat-Free Growbag all received Best Buys for seed sowing composts. Meanwhile, B&Q Multipurpose, B&Q John Innes No 2 and Westland West & Multi Purpose Compost were given Best Buys for growing on small plants.

However, Which? Gardening awarded Don’t Buys to two composts – Homebase Multipurpose Peat-Free and Vital Earth Seed & Cutting Compost. Both these products performed poorly overall in the seed sowing tests, with less than 40 per cent of seeds germinating when sown in these products.

Richard Gianfrancesco, head of research for Which?

Gardening, said: “One of the best things a gardener can do to help seeds or plug plants do well is grow them in good-quality compost, but with so many different products on sale it can be really tricky to know which one to choose.

“As our rigorous research has shown, choose well and young plants should thrive, but pick the wrong compost and you could end up with plants that either look sickly and unhealthy, or simply don’t germinate at all.”

Of course, the other option is to make your own seed compost which will save you money. It can be made out of organic ingredients such as leaf mould, coir and loam.

Seed composts should be well aerated and warm. They should be soil-less and consist of equal parts of fine textured bulking material such as coir and fine sand, which ensures effective drainage and aeration for germinating seeds. Ingredients should contain little in the way of additional fertilisers, as seeds don’t like high nutrient levels and may not germinate in rich mixtures.

One recommended recipe is one part leaf mould, one part grit cleaned from gutters, plus small amounts of used house plant compost with perlite.

However, two-year-old leaf mould is perfect to use on its own as a seed compost, said Heather Jackson, project coordinator at Garden Organic, the UK’s leading organic growing charity.

“You can’t make seed compost out of your normal compost as it will be too high in nutrients. The ideal growing medium for seeds is twoyear- old leaf mould, which is spongy, light, low in nutrients, keeps moist and you don’t have to sieve it.”

Another alternative is to collect molehill soil, which is very fine but fairly weed free and not nutrient rich, she said. Mix that with grit and it should make a good seed compost. It is also possible to re-use home-made seed compost for another crop once your seedlings have been pricked out, she said.

● The full report on the seed compost trials is featured in the January/February edition of Which? Gardening. For a free Which? Gardening guide: Grow Your Own, call 0800 389 88 55 quoting VEG44F.

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