Re: modern potting mixes

David Poole wrote:
> 
  Here in the post war years, the introduction of the John Innes
formulae enabled a standard to be set ....,  Peat/coir/coco shell based
> composts have largely superseded these on account of their ease of use
> and comparative lack of weight.  Personally, I loath them because they
> cannot sustain nutrient levels for long, all manner of trace element
> and mineral deficiencies crop up with alarming ease and invariably,
> the structure breaks down creating sodden, over compacted conditions
> after a short time.

Hi Dave
Just making a valiant effort at getting my mail up to date! 

I think as well the lack of weight can sometimes be a distinct
_disadvantage_ .Where the plant has a lot of top hamper it can very
easily become unstable.

Another nasty habit these media have is drying out and unless one is
vigilant and determined, proving very difficuly to re-wet right through.

Here the favourite medium at present is ground pine bark (an
easily-obtainable waste product of our timber industry) It seems to have
most of the undesirable traits of the others you mention. 

For interest I bought myself a block of the so-called palm peat imported
from Sri lanka and had fun rehydrating it. About a year ago I tried it
in a seed-raising mix with disasterous results -almost nothing
germinated. I also put some into a potting mix and had no luck with that
either. So there it sits in its container while I puzzle how to dispose
of it - probably the rubbish bag is the only safe place.
> 
> For convenience, I use an expensive and extremely good quality John
> Innes mix together with a soilless compost to provide a degree of
> lightness and plenty of good sharp sand to improve drainage.  A big
> handful of pelleted chicken manure per barrow load completes the
> mixture and this has worked remarkably well as a base for diverse
> groups such as Boronias (more sand added) bananas (more chicken ****
> added) and bromeliads (no chicken **** added).  For plants in pots and
> large containers, this mixture lasts well and is still in 'good heart'
> 2 or 3 years later.
JI mixes have gone totally out of favour here in the commercial field. I
doubt  now most people would have the slightest idea how to make them,
which I think is a great pity. 

I now use entirely a very simple mix of my own matured compost with a
sand/ground pumice combination, together with kelp powder for trace
elements. I then modify this on similar lines to yours - extra sand for
some and some garden soil (best vegetable garden) plus sheep manure
pellets for others. This seems to give maximum growth and good health
and who could ask for more.

Moira
 
> Dave Poole
> TORQUAY  UK

-- 
Tony & Moira Ryan <theryans@xtra.co.nz>
Wainuiomata, 
New Zealand (astride the "Ring of Fire" in the SW Pacific).
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