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.
- 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
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.