John Innes Sterilised Compost

Many suppliers offer John Innes potting compost in grades 1, 2 and 3 plus John Innes Seed Compost for sowing seeds; John Innes Cutting Compost for rooting cuttings and John Innes Ericaceous Compost for plants which cannot tolerate lime. The proportion of each constituent varies according to the type and end use of the compost.

Contents of John Innes Compost

• Loam is the most important ingredient in the compost as it provides the main “body” of the compost.

• Sphagnum Moss Peat in the John Innes Compost increases the total porosity and improves both the aeration and the water-retaining capacity. Peat decomposes slowly into humus.

• Coarse sand or grit is used as a physical conditioner to allow excess water to drain from the compost and thus prevent water-logging. It also helps to provide stability for larger plants.

• The compound fertiliser in John Innes Compost include; nitrogen for top growth, phosphates for root growth, potash for flowers and fruit plus trace elements.

More detail and historical information is provided by the John Innes manufacturers association