The John Innes Centre and John Innes compost

John Innes composts were developed in the 1930s by William Lawrence and John Newell working for The John Innes Horticultural Institution. The Institution was founded at the bequest of City of London merchant John Innes in 1910. You can read more about the John Innes Horticultural Institution at History of JIC and at our Centenary website.

Lawrence and Newell set out to formulate composts that would give consistently good and reliable results. Their particular motivation was the difficulty they were having in growing Chinese Primrose (Primula sinensis) for experimental purposes. Their objective was to obtain more reliable germination and growth among their experimental materials by standardizing growing conditions, including the growing medium. Through experimentation they established methods of heat sterilising the compost to destroy pests and diseases that did not cause any checks to plant growth. They also determined the physical and nutrition qualities needed in compost to achieve optimum plant growth. Lawrence and Newell also took into account the need to alter the nutritional status of the compost according to the plant's growth stage. Their research led to the introduction of the two standard composts, one for seed sowing and one for potting, which revolutionised the growing of pot plants.

John Innes Seed Compost - with a low nutrient level suitable for sowing seeds and rooting cuttings.
John Innes Potting Composts 1,2 &3 - with balanced nutrients to feed plants over an extended period.

The Institution made the formulae generally available, but never manufactured the composts for sale or otherwise benefited financially from their production.

The John Innes recipe

Loam is the most important ingredient in the compost as it provides the main "body" of the compost. It also forms the base of plant nutrition by supplying clay which absorbs and releases plant nutrients as required. Loam also contains essential micro-elements and some organic matter which provides a slow release of nitrogen to the plant.
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 provides the wide spectrum of plant nutrients needed for balanced growth.

Further information on John Innes composts can be obtained from:

John Innes Manufacturers Association
Horticulture House
19 High Street
Theale
Reading
Berkshire
RG7 5AH

E-mail: john.innes@the-hta.org.uk

and the books 'Seed and potting composts' written by Lawrence and Newell and 'Catch the Tide' written by Lawrence:

Seed and potting composts
William JC Lawrence & John Newell
London: Allen & Unwin,1939

Catch the Tide (Adventures in Horticultural Research)
W.J.C. Lawrence
London: Grower Books 1980
ISBN 0 901361 46 1