John Innes potting compost

Most potting compost or media offered is soil-less and either based entirely on peat, has some peat in its formulation or is peat-free. There are advantages, however, to soil based media and John Innes mixes are widely used. Be aware though; currently offered JI composts may differ from the traditional product and some still contain peat.

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Planted container and John Innes potting compost

Quick facts

  • JI composts originated in the 1930s at the John Innes Horticultural Institute then at Merton, Surrey
  • Loam is the crucial ingredient but is in short supply
  • Modern John Innes media contain soil ingredients that are not necessarily loam
  • JI composts are especially useful for long term planting as the soil fraction is very stable
  • They are easy to manage as the soil has a high level of buffering avoiding fluctuating water and nutrient content

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