On 22/05/2019 12:30, Chris Hogg wrote:
On Wed, 22 May 2019 10:00:14 -0000 (UTC), (Nick
Maclaren) wrote:
In article ,
Roger Tonkin wrote:
Bit confused about Nicks comment on "soilless" compost. I used
a standard garden centre product Levington Potting compost with
added John Innes, what ever that may mean,
Er, did it SERIOUSLY say that? If so, God alone knows what it means,
because the marketdroids that wrote that text assuredly didn't.
I see it for sale in our local Wyevale GC. As you say, God alone knows
what it means. I avoid it, regarding it as purely a sales pitch to
attract those who've heard of JI, but don't really understand what it
means.
John Innes compost is a class of composts, made mostly from 'soil'
(including sand and some clay). Soilless composts are made from
(traditionally) peat and (mostly nowadays) coir etc. The difference
I was referring to is that clay holds mineral nutrients far better
than the soilless material does, which is why soils without it need
so much humus (which also holds them).
The executive summary is that plants in pots run out of nutrients
more thoroughly in soilless than John Innes composts, so need them
replacing.
+1 to that explanation
I was brought up with JI compost, we used to make our own, with a small
boiler belting out steam to steralize the soil. we made around 10 tons a
year.
7 parts by loose volume medium sterilized loam
3 parts by loose volume good peat or peat substitute
2 parts by loose volume coarse sand
b) Fertilizer mix (John Innes Base)
2 parts by weight hoof and horn meal
2 parts by weight superphosphate
1 part by weight sulphate of potash
Then in the late 50's U C (University of California) came up with soil
free compost.
For your old compost I'd re use it, possibly with about 20% of new added
and I'd use Vitax Q4 to re feed it as it has trace elements.