Re: potting soil observation

Greetings -

When I was doing my MS in Horticulture, another grad student did some
experiments with creating inexpensive potting mixes.  The most inexpensive
mix that worked well for a variety of plants was made of just ground
redwood compost & clay cat litter (the old-fashioned type).

The amounts of each were varied by the need to hold moisture:
	standard potting mix = 1 part each
	cactus/succulent mix = 2-3 parts cat litter/1 part redwood
	high moisture retention mix = 2-3 parts redwood/1 part cat litter
You can add nutrients as appropriate & adjust the pH when needed.

I still use this mix for most of my potted plants outdoors & for some of
my indoor potted plants.  Here in California, the redwood is readily
available as Jan notes & you can use the cheapest clay cat litter
available.  I do suggest that you always rinse the cat litter before
mixing it with the redwood.

Dana

On Thu, 17 Jun 2004, Tony and Moira Ryan wrote:

> Jan Smithen wrote:
>
> > In "Container Gardening" classes sooo many years ago, I found we had to make
> > our own potting mix because it was too expensive to buy for that many
> > people. I used the Univ. of Cal. 2 to 1 ratio: 2 organic to 1 inorganic
> >     1 part compost, 1 part washed coarse sand, 1 part ground up redwood
> > (called redwood soil amendment in those days) To that we added 2 Tbsp. kelp
> > meal OR 2 Tbsp. Gro-Power for every 2 gal. bucket of mix. Depended on what I
> > could find in those days.
> >
> > Lots of work, mixing and blending, but it worked very well and taught me the
> > value of grit in a soil mix.
>
> Jan
> This is very similar to the mix I use, though I got my recipe from some
> NY lab which was quoted in Organic Gardening in the days when it was
> still a useful publication. Mine however uses just compost for its
> organic portion. With my own compost this seems substantial enough for
> small containers and for large pots I do add some soil as well. I am
> sure  I could get ground bark here quite easily, as pine bark is the
> medium of choice for many commercial mixes and I might try your recipe
> some time. My experience with mixes using bark only for their organic
> fraction is definitely not favourable though, as on its own it tends to
> be a bit like peat - once it has dried out it is extremely difficult to
> rewet and  watering consequently almost always involves regular soaking
> of the pot. In any case such mixes, unlike those with compost have very
> little intrinsic food value and usually depend on regular additions of
> chemical fertilizers to sustain the plants.
>
> I find my compost-only  plus kelp meal mix is very adequate for the
> majority of plants in my greenhouse for at least one growing season. For
> some of the larger and more permanent plants though I do add a substance
> called Magamp which is easily obtained here. It comes in the form of
> irregular granules and is in effect an artificial rock containing NPK
> and Magnesium chemically combined in a form which allows only slow
> release and so is not a danger to living organisms, which can draw on it
> as required. It can be used in open ground also, where its effects last
> easily up to two years for one application. In my business days I used
> it very effectively for establishing new roses for instance..
>
>   For my grit fraction I use a half and half mix of propagating sand and
> coarsely ground pumice (both freely available from my favourite garden
> centre). I am interested to hear though of someone else using just grit
> and not Vermiculite or perlite, both of which are both hard to get here
> and expensive when one does.
>
> I found the easiest way to do the mixing was to spread the ingredients
> out on large piece of plastic sheet. Quite a lot of the stirring can
> then be done simply through rolling the heap over trough lifting the
> sides of the plastic.
>
> --
> Tony & Moira Ryan,
> Wainuiomata, North Island, NZ.     Pictures of our garden at:-
> http://mywebpages.comcast.net/cherie1/Garden/TonyandMoira/index.htm
> NEW PICTURES ADDED 4/Feb/2004
>

Dana Drennan
Davis, CA 95616
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