The term Compost can have more than one meaning; there is Compost
the growing medium and
Compost the material produced in a compost heap (see Composting).
For the purposes of this information sheet we will be discussing
Compost the growing medium.
Composts comprise a growing medium such as peat with added
nutrients and sometimes other
materials such as sand or grit. Peat is still the most effective
medium but alternatives are now being
used to prevent environmental damage to the peat bogs.
There are 3 main groups of Compost:
1. Peat Based Composts e.g. Levington, Murphy's, J. Arthur Bowers
2. Low Peat/Peat Free Composts e.g. The "Nature's Way" range
of low peat composts by Levington
3. Soil based Composts e.g. "The John Innes
Range of Composts:
Within each group of compost there is a range of composts formulated
to do different tasks.
The main types are:
usually a fine textured compost and relatively low in fertilizer
to avoid "burning"
Coarser in texture and higher in fertilizer for greedier more
Compost: Does exactly what it says it does, a
half way house between a seed and a
potting compost - a jack of all trades (master of none?)
Compost: A recent development and a worthwhile
one. Basically a potting
compost with added water retaining material and/or slow release
Compost: Basically a potting compost
with enough added fertilizer to last a whole
season - for larger, mature plants.
Formulated without using Lime to suit "Lime hating plants".
Compost with Insect Control:
Expensive and with a short shelf life as the insect control element
Compost with Moisture
Control: Added water retaining granules to help
prevent drying out.
May also contains slow release fertilizer.
There are further ultra specialist composts such as:
Bonsai, Alpine, Cactus, Orchid, Citrus,
Houseplant, African Violet etc.
John Innes Range:
- John Innes Seed Compost is self explanatory.
- John Innes No.1 is formulated for younger/small plants or
Very similar to the seed compost.
- John Innes No.2 has a higher fertilizer content than No.1
so is suited to established plants.
Equivalent to multipurpose compost.
- John Innes No.3 has a higher fertilizer content than No.2
and is suited to larger/mature plants.
Equivalent to potting compost.
N.B. - Being soil based, John Innes composts tend to be
heavier than peat based ones so are
not available in sizes above 25 Litres. Being soil based
they are low in Peat.