Growing medium

Peter Taggart
Wed, 11 Jul 2012 13:34:07 PDT
I use 'sterile' ingredients.

I dig topsoil from the second spade down or else buy loam with a clay
content, designed for cricket pitches and tennis courts, I sometimes use
concrete (coarse)sand, I buy peat or "multipurpose" (humus based) compost,
I make leaf mould from hedge clippings and leaves which I am careful not to
put seeds of weeds such as grass or bluebells in -or plants such as
Ranunculus ficaria, and the grits I buy are effectively sterile too, 3-6 mm
"Horticultural Grit" is cheapest at around £2.00 for 25 K but finer grits
are sometimes better (and are more expensive) in the mixes the cheapest of
these are Dashing Grits. I use 6 or 10 mm gravel for topping.

I have considered buying a steriliser (Heat) in order to sterilize used
compost, (and heat the greenhouse), but I haven't done this yet.

My main mix contains ratios of perhaps 3 bags 6mm grit, 2 bags 2-3mm grit,
1 bag coarse sand, 4 bags loam and 2 bags JI no 3 or "Top Soil" (both
products have become very high in humus now). I add fertiliser.

Essentially this mix is  50/50 aggregate to soil.

I then mix in humus as required and sometimes extra sand, I plant both
seeds and bulbs in this, Trilliums would get an equal volume of humus and
leaf mould , crocus would get about 1/3 leaf mould and extra sand. most
Alliums, leontocoides Corydalis, Rhinopetalums, scree dwellers and Tulips
would get the 50/50 mix, as would most junos though  a few get extra humus
(eg aucheri, cycloglossa..)
Peter (UK)

On Wed, Jul 11, 2012 at 7:49 AM, Bulborum Botanicum <>wrote:

> Hello Peter
> How do you sterilise larger quantities seeding mixture

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