John Innes compost replacements

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Paul D
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Re: John Innes compost replacements

Post by Paul D »

Here's an update on the Sylvagrow Ericacous.
I passed the whole 50 litre bag through a 6mm (1/4") garden griddle, and ended up with a couple of carrier bags full of coarse bits. Not too bad, really.
coarse bits.jpg

The remaining texture is quite good, but I'm planning on putting it through a 3mm grid once it arrives. My plan is to use it in place of peat, rather than as a complete compost, and make up my own John Innes.
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6mm sievings 2.jpg
6mm sievings 1.jpg
Paul in North-east Scotland (Grampian Branch BCSS)
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http://www.rebutia.org.uk
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Paul D
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Re: John Innes compost replacements

Post by Paul D »

I've finished making my John Innes Ericacous Compost substitute, and I'm pretty pleased with the result.
I started with the traditional recipe, which is:

2 parts loam
1 part peat
1 part sharp sand
Then for every cubic metre (i.e. 1000 litres!), add 600g sulfur and 1200g superphosphate


Translating that into more manageable quantities and replacing the peat component, I get:

20 litres sterilised topsoil
10 litres Sylvagrow Ericacous Compost, sieved with 6mm then 3mm grid, lumps removed
10 litres sharp sand, horticultural quality (watch out for salt in builders' sand)
24g sulfur
48g superphosphate

All mixed up in a big trug bought from Amazon:
John Innes sub process.jpg
The 6mm sieve is a typical garden centre circular garden one. I had to make the 3mm one myself from an A3 bit of 3mm steel mesh bought from "the mesh company" and some old offcuts of tongue-and-groove wood.

The Sylvagrow Ericacous component does actually contain fertiliser in the bag, but given that the "peat" component is 1/4 of the mix, and the compost will be going into my cactus mix which is 75% drainage material, I don't think I need to worry about the quantity of fertiliser too much.

The final mix is quite friable, doesn't clump, and just has a good feel about it.
John Innes sub finished.jpg
Comparing it to my usual "Clover" brand, the Clover is a little lighter in weight, blacker, and I would guess contains more peat than my home made version. I don't know what flexibility there is in the original recipe in order to still call it "John Innes" but I suspect there is quite a lot, given the huge variety of quality on the market!

Of course if you wanted a John Innes No. 2 or No. 3 then the recipe is slightly different as it contains lime.
If anyone has any criticisms or additions to my recipe, please let me know. It's a work in progress.
Paul in North-east Scotland (Grampian Branch BCSS)
National Collection Rebutia, Aylostera & Weingartia (inc. Sulcorebutia). Also growing a mixture including Ferocactus, Gymnocalycium, Lobivia, Mammillaria, Lithops, Gasteria, Haworthia.
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Re: John Innes compost replacements

Post by edds »

Looks really good Paul. I chickened out of DIYing it for a while and bought a load of JI and grit. Will be very interested to see how this does and copy it shamelessly next year if it works for you. I can see me ordering half tonnes of the various ingredients and mixing it up in my cement mixer!

I bought the Clover JI this time compared to the Westfield stuff I've been using before and would agree about the peat content. The Westfield stuff feels like it has much more loam and sand/grit than peat/compost when compared to the Clover.
Ed

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Re: John Innes compost replacements

Post by ralphrmartin »

Interesting. I wonder what our local garden centre will be selling when the peat based ones are sold out. It seems different brands are to be found in different parts of the country, which makes sense, as transporting heavy stuff like compost a long way is probably uneconomic (as well as not very green).
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Re: John Innes compost replacements

Post by MatDz »

Paul D wrote: Thu Jun 02, 2022 4:21 pm 20 litres sterilised topsoil
10 litres Sylvagrow Ericacous Compost, sieved with 6mm then 3mm grid, lumps removed
10 litres sharp sand, horticultural quality (watch out for salt in builders' sand)
24g sulfur
48g superphosphate
Paul, a few questions to your recipe above:

1. My SylvaGrow Ericaceous Compost seems to have a lot of "not so fine" bark and coir, there isn't much left after a 3 mm sieve. Was yours the same, or did I just get unlucky here?

2. Sulphur and superphosphate - sulphur has some antifungal properties and I have flowers of sulphur at hand, but can superphosphate simply be replaced by regular fertilization with all the various Chempaks available, or does it have another role here?

3. Did you come to any major modifications in the recipe after your research?
Mat
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Paul D
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Re: John Innes compost replacements

Post by Paul D »

MatDz wrote: Mon Jul 18, 2022 11:21 am
Paul D wrote: Thu Jun 02, 2022 4:21 pm 20 litres sterilised topsoil
10 litres Sylvagrow Ericacous Compost, sieved with 6mm then 3mm grid, lumps removed
10 litres sharp sand, horticultural quality (watch out for salt in builders' sand)
24g sulfur
48g superphosphate
Paul, a few questions to your recipe above:

1. My SylvaGrow Ericaceous Compost seems to have a lot of "not so fine" bark and coir, there isn't much left after a 3 mm sieve. Was yours the same, or did I just get unlucky here?

2. Sulphur and superphosphate - sulphur has some antifungal properties and I have flowers of sulphur at hand, but can superphosphate simply be replaced by regular fertilization with all the various Chempaks available, or does it have another role here?

3. Did you come to any major modifications in the recipe after your research?
Since I posted that i've done a lot of modifications and more research, with a view to not just arriving at a peat-free "John Innes", but also a sustainable one in terms of the other ingredients. There shouldn't be coir in the Sylvagrow, so that's puzzling. I found that the 6mm sieve was enough though (a few lumps but still way better than the commercial bagged JI composts), I am only using the 3mm for seed compost.

I've abandoned the sterilised topsoil as the resulting pH was too high. I'm now going with acidic ericaceous loam as the mineral soil component. It is still not ideal as it is very sandy.

Having found the original publications I've also abandoned the sharp sand, as although it was described as sand (and repeated as sand is more recent publications), it is actually supposed to be what we would now call grit up to 3mm particle size. I've tried a few alternatives and am now using Melcourt Horticultural Potting Grit, which is Cornish granite with some quartzite.

The properties of Sulphur are affected by the lack of moisture, so I'm not sure how effective it is for our xerophytic plants. One of the key effects of it is to reduce the pH of the soil, but again this is affected by lack of moisture. Most organic fertilisers are also affected by lack of moisture as they rely on the actions of bacteria to make nutrients available to plants.

The purpose of the superphosphate is to give newly potted plants a head start with root production, I guess. That, together with the N and K and other elements in the organic component of the compost, should be enough to last the first few weeks for our mostly not-very-demanding plants. Thereafter, additional feed is needed.

Anyway, I've written up what I've found so far for publication, but it is an ongoing project. Now that I've arrived at what I think is a decent base medium, I'm embarking on a trial of replacing superphosphate, which is derived non-sustainably, with a variety of different products, phosphate-only and more balanced, including struvite-derived and seaweed-derived fertilisers, plus the traditional meat-product and quarried ones. I've spent the last month or two accumulating these. Some slow release, some immediately water soluble. I have a couple of hundred one-year-old seedlings ready to volunteer in the spring. Will report in due course!

Of course then there is the question of the sustainability of the loam and the grit...I guess by finding a method of recycling / revitalising.
Paul in North-east Scotland (Grampian Branch BCSS)
National Collection Rebutia, Aylostera & Weingartia (inc. Sulcorebutia). Also growing a mixture including Ferocactus, Gymnocalycium, Lobivia, Mammillaria, Lithops, Gasteria, Haworthia.
http://www.rebutia.org.uk
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Re: John Innes compost replacements

Post by MatDz »

Thank you for this extended reply, am looking forward to seeing the article in print soon!

Just a few points:
Paul D wrote: Mon Jul 18, 2022 12:38 pm There shouldn't be coir in the Sylvagrow, so that's puzzling. I found that the 6mm sieve was enough though (a few lumps but still way better than the commercial bagged JI composts), I am only using the 3mm for seed compost.
The manufacturer (https://melcourt.co.uk/products/sylvagrow-ericaceous/) states that it's "a unique blend of fine bark (a by-product of sustainably managed British forests) and coir (from known, ethically-approved sources)", so I guess it shouldn't be that surprising.
Paul D wrote: Mon Jul 18, 2022 12:38 pm I've abandoned the sterilised topsoil as the resulting pH was too high. I'm now going with acidic ericaceous loam as the mineral soil component. It is still not ideal as it is very sandy.

[...]

I've tried a few alternatives and am now using Melcourt Horticultural Potting Grit, which is Cornish granite with some quartzite.
That's a bit of a shame after I finally found it, but it feels perfect to keep Mexican cacti in a loamy, more alkaline mix I wanted to try, mainly for visual reasons.

I had a look at the ericaceous loam and it seems to be available solely in bulk quantities, will need to think about it more. Joys of living in the centre of London with no proper garden centres around...

And this grit brand really is promising, with particle size significantly finer than the RHS branded one!
Mat
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Re: John Innes compost replacements

Post by Paul D »

MatDz wrote: Mon Jul 18, 2022 2:48 pm
The manufacturer (https://melcourt.co.uk/products/sylvagrow-ericaceous/) states that it's "a unique blend of fine bark (a by-product of sustainably managed British forests) and coir (from known, ethically-approved sources)", so I guess it shouldn't be that surprising.
Apologies, I was wrong about that. Though I certainly don't have much in the way of fibrous material in the bag I have here. I will see if I can find out what the proportions are.
MatDz wrote: Mon Jul 18, 2022 2:48 pm That's a bit of a shame after I finally found it, but it feels perfect to keep Mexican cacti in a loamy, more alkaline mix I wanted to try, mainly for visual reasons.

I had a look at the ericaceous loam and it seems to be available solely in bulk quantities, will need to think about it more. Joys of living in the centre of London with no proper garden centres around...
I'm not completely sure about it yet but yes, its a bulk bag. I can use some of it for rhododendrons. We don't have much in the way of retail here in the back of beyond either!
MatDz wrote: Mon Jul 18, 2022 2:48 pm And this grit brand really is promising, with particle size significantly finer than the RHS branded one!
Yes it seems ideal. A good range of sharp particle sizes.
Paul in North-east Scotland (Grampian Branch BCSS)
National Collection Rebutia, Aylostera & Weingartia (inc. Sulcorebutia). Also growing a mixture including Ferocactus, Gymnocalycium, Lobivia, Mammillaria, Lithops, Gasteria, Haworthia.
http://www.rebutia.org.uk
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Paul D
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Re: John Innes compost replacements

Post by Paul D »

MatDz wrote: Mon Jul 18, 2022 2:48 pm The manufacturer (https://melcourt.co.uk/products/sylvagrow-ericaceous/) states that it's "a unique blend of fine bark (a by-product of sustainably managed British forests) and coir (from known, ethically-approved sources)", so I guess it shouldn't be that surprising.
I've had a reply from Melcourt, and they say it is 2/3 bark and 1/3 coir. But they also do a product which is 100% composted bark fines, without the added feriliser. I have ordered a bag to look at.
Paul in North-east Scotland (Grampian Branch BCSS)
National Collection Rebutia, Aylostera & Weingartia (inc. Sulcorebutia). Also growing a mixture including Ferocactus, Gymnocalycium, Lobivia, Mammillaria, Lithops, Gasteria, Haworthia.
http://www.rebutia.org.uk
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Re: John Innes compost replacements

Post by MatDz »

Paul D wrote: Tue Jul 19, 2022 10:59 am I've had a reply from Melcourt, and they say it is 2/3 bark and 1/3 coir. But they also do a product which is 100% composted bark fines, without the added feriliser. I have ordered a bag to look at.
Your sacrifices won't be forgotten!

Any chances for a quick look at the draft of the article?
Mat
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