John Innes Compost


 

John Innes is not a manufacturer of compost, they are a range of composts developed at the John Innes Institute, and named after John Innes, a nineteenth century property and land dealer in the City of London.

On his death in 1904 he bequeathed his fortune and estate to the improvement of horticulture by experiments and research.

The result was the establishment of the John Innes Horticultural Research Institute initially at Merton in Surrey, but now located at Norwich.


The essence of Ji composts from today's point of view is that they are 'Loam based', as opposed to 'Peat Based' or 'Peat Free'

There are several formulae, depending on the use of the compost, they are as follows:


JI Seed Compost: is for sowing seeds in.

JI Cutting Compost: is as the name suggests, for rooting cuttings.

JI No 1 Potting Compost: is the type for pricking out young plants into.

JI No 2 Potting Compost: is for potting on to the next stage of a plants development.

JI No 3 Potting Compost: is for established plants and shrubs that will remain in containers for quite some time.

JI Ericaceous Compost: is the type for pricking out young plants that cannot tolerate lime.

 

The Ingredients:


The function of each of the ingredients in John Innes is briefly as follows;


Loam:


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 has a cation and anion exchange capacity, that is, it 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.


Peat:


Sphagnum Moss Peat in the compost increases the total porosity of the compost, and also improves its aeration and water-retaining capacity.

Peat decomposes slowly into humus.


Sand:


The 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.


Fertiliser:


The compound fertiliser in John Innes Compost provides a wide spectrum of plant nutrients needed for balanced growth, including:

Nitrogen - for top growth.

Phosphates - for root growth.

Potash - for flowering and fruiting.

Trace Elements - for optimal growth, colour and (where appropriate) flavour.

Nutrients are typically sufficient for 1-2 months of growing, after which time additional proprietary feed should be given.


Recipes:

Method:

The Loam and Peat is measured by volume then put through a 9mm (3/8 in) sieve, to which coarse sand or grit is added.

Fertiliser is then added to the sieved material in proportions to make one cubic metre of the compost type.


Seed Compost

 

Main Constituents

 

Fertilisers

The traditional mix for sowing almost any type of seed, with sufficient nutrient for early development.

This mix can also be used for rooting soft cuttings.

 

2 parts sterilised Loam.

1 part Peat.

1 part Coarse sand or Grit

 

0.6kg ground limestone.

1.2kg superphosphate.



Cuttings Compost

 

Main Constituents

 

Fertilisers

As the name suggests, for rooting cuttings in.

 

1 part Loam.

2 parts Peat.

1 part Coarse sand or Grit

 

No added fertiliser.



Ji Potting Compost No.1

 

Main Constituents

 

Fertilisers

For pricking out, or potting-up young seedlings or rooted cuttings.

This composts has a carefully balanced nutrient content to suit most young plants.

 

7 parts Loam.

3 parts Peat.

2 parts Coarse sand or Grit

 

0.6kg ground limestone.

1.2kg hoof and horn meal.

1.2kg superphosphate.

0.6kg potassium sulphate



Ji Potting Compost No.2

 

Main Constituents

 

Fertilisers

For general potting of most house plants, and vegetable plants into medium size pots or boxes.

Contains double the amount of nutrient in JI No 1 to suit established plants

 

 

7 parts Loam.

3 parts Peat.

2 parts Coarse sand or Grit

 

0.6kg ground limestone.

2.4kg hoof and horn meal.

2.4kg superphosphate.

1.2kg potassium sulphate



Ji Potting Compost No.3

 

Main Constituents

 

Fertilisers

This is a richer mixture for final re-potting of gross feeding vegetable plants and for mature foliage plants and shrubs in interior planters or outdoor containers.

 

7 parts Loam.

3 parts Peat.

2 parts Coarse sand or Grit

 

0.6kg ground limestone.

3.6kg hoof and horn meal.

3.6kg superphosphate.

1.8kg potassium sulphate



Ji Ericaceous Compost

 

Main Constituents

 

Fertilisers

The traditional mix for sowing almost any type of seed, with sufficient nutrient for early development.

This mix can also be used for rooting soft cuttings.

 

2 parts Loam.

1 part Peat.

1 part Coarse sand or Grit

 

0.6kg flowers of sulphur.

1.2kg superphosphate



As can be seen the above recipes are for mixing quite large quantities of JI compost and not necessarily the amounts the average gardener is likely to use.

An approximate conversion would be 1litre = 0.075 cubic metres meaning:

To each litre of mix, add;


Seed Compost

JI No.1

JI No 2

Ji No 3

Ji Ericaceous

         

50 gms ground limestone.

100gms superphosphate.

50gms ground limestone.

100gms hoof and horn meal.

100gms superphosphate.

50gms potassium sulphate.

50 gms ground limestone.

200gms hoof and horn meal.

200gms superphosphate.

100gms potassium sulphate.

50gms ground limestone.

300gms hoof and horn meal.

300gms superphosphate.

150gms potassium sulphate

50gms flowers of sulphur.

100gms. superphosphate.

         
Note: One can dispense with measuring out these various ingredients by buying a pre-packed JI base fertiliser from good garden centres. (see here)

Sadly Ji composts are becoming less common due to the lack of good quality loam and the cutting back on the use of peat.


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