Cultivation > Composts

John Innes

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David Nicholson:

--- Quote from: Maggi Young on March 21, 2007, 09:36:34 PM ---
--- Quote ---I firmly believe that at least a SMALL quantity of basic loam or garden soil is very beneficial in virtually all potting mixes. There are pathogens and other greeblies (you note my scientific turn of mind?) that peat or bark based mixes are lacking and which help keep harmful fungi etc at bay.
--- End quote ---
I'm with you there, Lesley, that's why I am doubtful about sterilising composts.... too many good guys getting frazzled with the baddies! I'm sure the baddies are better at re-colonizing than the goodies, too.
not saying it is never necessary to  sterilise a growing medium, but it never happens here. Not after I discovered how bloody awful soil smells after Ian blitzed it in the microwave, anyhow! :-\ :-X :-[



--- End quote ---

Maggi I agree. Quite honestly I can't see manufacturers of JI type composts spending money on sterilising loam, they would much rather look for ways of putting in the least possible amount of loam they can get away with. One of my Auricula growing friends gave me a little tip to test the quality of loam based compost and I will pass it on here. Take one clean jam jar with lid-take one handful of compost and add it to jam jar. Top up jam jar with cold water add lid and shake. Allow to settle, loam sinks, humus stays in suspension. It's a little rough and ready but if you try it you will see if you have any of either (Loam and humus that is) I'm rambling again, must be getting tired! ::)

Lesley Cox:
Sounds like an interesting way to revert to one's childhood David. I seem to remember having different things in jam jars to my mother's horror. She was never sure what was in the fridge that could crawl out, or maybe get added to a casserole by mistake.

Yeah Maggi, that smell sure is horrible!

illingworth:
Hi Lori,

We were waiting for you to re emerge and you did so on the first day of spring! Perfect timing.

We use Sunshine Jiffy 4 mix to which Sharon adds perlite and chick grit number 2 (granite chips), and sometimes a bit of sand or some leaf mould, depending on what is being potted up.  We have also added Turface to the mix but have cut it out as we think it promotes the growth of liverworts. This is just used as a seed germination mix or for growing on prior to establishing in the garden - not for long term pot culture - which we don't generally do.

-Rob
http://www.flickr.com/photos/illingworth/

Loripep:
Thanks everyone;

Think I will try the mix recommended by Rob. He and his wife Sharon have a beautiful garden and kindly toured me through it last summer. All in a cold Canadian zone 3 or 4!

Love the pictures of the garden Rob.

Lori

Rodger Whitlock:

--- Quote from: Loripep on March 21, 2007, 06:46:48 PM ---I was wondering if someone can tell me of a Canadian brand of potting soil which is equivalent to John Innes 1 or 2. Is there such a beast?
--- End quote ---

The John Innes mixes are characterized by:

1. texture, including content of organic matter, clay fraction, and minerals (sand)
2. pH
3. nutrient levels

I mix an approximation to the JI potting compost as follows:

IngredientQuantityCommentIsland's Finest Top Soil    30 liters    from Canadian Tireperlite10 litershorticultural grade! Perlite sold for building insulation may contain fluorides toxic to plants4-6-8 organic veg. fertilizer144 gfrom Canadian TireLimelime, not dolomite; amount depends of pH of bagged soil    pH = 4203 g    pH = 4.5168 g    pH = 5135 gfritted trace elements7 g


You should be able to buy these ingredients locally, except the "top soil." It's a local product here on Vancouver Island, dredged from an old lake bed and bagged without treatment. In devising this recipe I made the assumption that it contained silt and peaty organic matter in about the right proportion to match the JI formula for rotted turves plus peatmoss. It contains coarse debris (twigs, leaves, etc) and is bagged very wet, so I spread it out to dry and when dry screen it to remove the debris.

The amount of lime is calculated to give pH 6.5 in the finished mix.

In practice, I find that the amount of perlite is a little low and the mix is a little too dense and airless for many plants, so I mix 1 part perlite to 2 parts of this soil mix when potting up many things. For seeds, I mix equal volumes to give a light, airy mix that many seeds enjoy.

The moral of this somewhat long-winded description is that you can probably find suitable ingredients to make a rough approximation to the JI compost. What I mix may not be ideal, but at least I know what's in it. Friends to whom I've given some for potting their summer annuals say it works far better than any commercial potting mix made for the same purpose.

At one time I used granite chicken grit instead of perlite, but the grit became too costly, and perlite is very cheap when you buy a 100+ liter bag.

I'm sure members of the SRGC elsewhere can find similarly suitable make-do ingredients with which to mix a mock JI compost. As I said, at least when you do that, you know what you have in your hands!

Hope this helps!

Postscript: I see I failed to explain why I use the "Island's Finest Top Soil". Very simply, it's extremely cheap, often available for $2 (CDN) for a 30 liter bag. Also, though it contains natural debris and is ridiculously acid, it contains no additives of any sort, so I am not putting myself at the mercy of some stupid person with a bag of fertilizer.

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