Scottish Rock Garden Club Forum

General Subjects => General Forum => Topic started by: JPB on July 03, 2010, 09:25:53 AM

Title: DIY John Innes compost
Post by: JPB on July 03, 2010, 09:25:53 AM: Finally I have found a good source for loam and have made my own JI-nr2 mix.
I found some recipes using this mix for specific aplications (Alpines, Bulbs). But how do you mix it for other plants (woodland; mediterranean; succulents)? I have perlite, sand, grit, vermiculite, peat moss, dolomite lime. No good leafmold, though..

Can you show me any recipes that work well for specific plants you grow?

Hans
Title: Re: DIY John Innes compost
Post by: Rodger Whitlock on July 03, 2010, 07:05:44 PM: One point about the John Innes composts that is often overlooked: the pH is regulated with lime so it ends up at pH 6.5. Lime is added to the stack of turf to be rotted down into loam, and also to the final mix. Note that in this context "lime" means calcium carbonate: ground chalk or limestone. Dolomitic lime will not work as well.

As for mixes for various categories of plants, Royton Heath's "Collector's Alpines" offers four different formulas. These are quite different from the John Innes formulas.

The John Innes formulas (and similar ones containing loam) have a considerable advantage over various soilless composts in that the loam provides a clay fraction. Clay is important in soil mixes because it adsorbs [n .b. adsorb, not absorb] nutrient ions very strongly, so they are not leached out as quickly by watering. The various soilless mixes that originated at the University of California, involving peat and vermiculite, have no clay, do not retain nutrients, and demand that the plant be regularly fed with solutions of fertilizers. In the warm, sunny California climate, this is fine, but in cooler, damper climates the need to be constantly pouring on fertilizers in solution means the potting mix is kept soaking wet, never a good thing for healthy plant growth.

I have used a "revised" John Innes mix for decades. Revision was absolutely necessary because some ingredients of the original JI mixes are simply unavailable: Cornish silver sand, and hoof-and-horn meal being the chief offenders. One can obtain here (western Canada) an organic granular fertilizer with analysis 4-6-8, which turns out to be very close to the overall analysis of the nutrients called for in the JI formulas. The chief difficulty I have now is sourcing decent soil to start with. For some years I've been using a bagged "top soil" that is actually recovered from a dry lake bed, in the belief that it has about the right proportions of organic matter and clay, but lately I've become concerned that the organic matter is too plentiful and the clay fraction too scant.

Another detail that is easily overlooked re the JI formulas is that superphosphate is added after pasteurization of the soil with steam.

Hope this helps.
Title: Re: DIY John Innes compost
Post by: iann on July 03, 2010, 09:21:27 PM: Hoof and horn is still available here, and probably in Canada too, but not exactly on every street corner. Commercial JI mixes now use synthetic fertilisers anyway for consistency in manufacturing and storage. Or you can mix up an "authentic" nutrient supply from the original superphosphate and potash plus a different nitrogen source such as a seed meal or even a coated urea. Make sure you don't add anything too rapidly soluble, the amount you should include would be toxic if it was released quickly.

I've used topsoil from my own garden plus soymeal, etc. No added peat for my cacti and it is already more than loaded with limestone, but for lime lovers it works great. I suspect on a larger scale I would sooner or later get some pest but then those branded JI bags have been known to contain nasties too.
Title: Re: DIY John Innes compost
Post by: johnw on July 03, 2010, 09:43:06 PM: Quote from: iann on July 03, 2010, 09:21:27 PM
Hoof and horn

Ian

In Canada you'd have a better chance finding a bar with that name rather than the goods. ;)

johnw
Title: Re: DIY John Innes compost
Post by: Rodger Whitlock on July 03, 2010, 09:57:49 PM: Quote from: johnw on July 03, 2010, 09:43:06 PM
Quote from: iann on July 03, 2010, 09:21:27 PM
Hoof and horn

In Canada you'd have a better chance finding a bar with that name rather than the goods. ;)

Are you proposing we go into business, say in Calgary? I can see the big flashing neon sign now,
HAVE A MEAL AT THE HOOF AND HORN!

[Yes, it's a pun, and a fairly excruciating one at that. I am unashamed.]
Title: Re: DIY John Innes compost
Post by: johnw on July 03, 2010, 10:23:16 PM: Quote from: Rodger Whitlock on July 03, 2010, 09:57:49 PM
Quote from: johnw on July 03, 2010, 09:43:06 PM
Quote from: iann on July 03, 2010, 09:21:27 PM
Hoof and horn

In Canada you'd have a better chance finding a bar with that name rather than the goods. ;)

Are you proposing we go into business, say in Calgary? I can see the big flashing neon sign now,
HAVE A MEAL AT THE HOOF AND HORN!

[Yes, it's a pun, and a fairly excruciating one at that. I am unashamed.]

Roger

Somehow I don't see a drive-through take-away in Calgary in my future! 8)

johnw
Title: Re: DIY John Innes compost
Post by: Lesley Cox on July 03, 2010, 11:21:09 PM: Haven't had hoof and horn specifically, but I'm finding my Teddy digs anything where I've added a little bonemeal. And while he has various toys, as dogs do, his best loved is an ancient ram's horn which we found in a load of compost a few years ago. Roger hung it in a tree and once Teddy had a sniff, he was in love with it for life.
Title: Re: DIY John Innes compost
Post by: JPB on July 06, 2010, 04:25:28 PM: Roger, do you add something (sand? perlite? whatever?) to the JI mix right out of the bag? My DIY mix is not that porous, although some plants grow well in it whithout adding anything (Veronica spicata, Cistus laurifolius and Scabiosa's). Paul cumbleton gives a recipe for his bulb mix, but are there any other standard mixes you use? Or references on the web?

What's wrong with dolomite? It releases its carbonate more slowly so I would think that is an advantage ???

I had a hard time to find out what Hoof & Horn Meal was, but it is called "Bloedmee" here (Blood Meal)", however, not made from hoofs and horns, so I'm not sure. It had 18% N and phosphate and potassium are in the other additives.

Hans
Title: Re: DIY John Innes compost
Post by: Rodger Whitlock on July 06, 2010, 05:51:19 PM: Quote from: Hans Pakker on July 06, 2010, 04:25:28 PM
Roger, do you add something (sand? perlite? whatever?) to the JI mix right out of the bag? My DIY mix is not that porous, although some plants grow well in it whithout adding anything (Veronica spicata, Cistus laurifolius and Scabiosa's).

Yes. I wasn't clear in my previous posting. The bagged soil I buy is used in lieu of the rotted turf the JI formulas call for. I then add lime, fertilizer, and perlite to bring the mix reasonably close to the JI formula. I also add fritted trace elements.

Quote from: Hans Pakker on July 06, 2010, 04:25:28 PM
Paul cumbleton gives a recipe for his bulb mix, but are there any other standard mixes you use? Or references on the web?

If you look through the "usual" ruck of books on growing bulbs and rock garden plants, you will find endless variations on soil mixes. At the end of the day they all seem to be reducible to a mix of three main components, soil (=the loam in the JI formulas), peat, and sand or grit, with assorted nutrients. Several decades of experience with such mixes has led me to think that the critical factor is air space, and, secondarily, drainage. For really difficult true alpines these mixes are too heavy, too airless, too poorly drained, so these days such plants go into volcanic pumice, which seems to agree with them.

I don't know of a web site with a comprehensive comparison of soil mixes.

Quote from: Hans Pakker on July 06, 2010, 04:25:28 PM
What's wrong with dolomite? It releases its carbonate more slowly so I would think that is an advantage ???

The lime is added to adjust the pH, not to provide nutrients, though adjusting the pH alters the availability of other nutrients. Dolomite is far less soluble and doesn't affect the pH very efficiently. If you need magnesium, a dilute solution of Epsom salts (magnesium sulfate) is easy enough to apply.

Quote from: Hans Pakker on July 06, 2010, 04:25:28 PM
I had a hard time to find out what Hoof & Horn Meal was, but it is called "Bloedmee" here (Blood Meal)", however, not made from hoofs and horns, so I'm not sure. It had 18% N and phosphate and potassium are in the other additives.

Hoof and horn meal was made from hooves and horns, ground up. I've never seen the stuff, but it probably provided a very slow release source of nitrogen. I just use a commercial fertilizer marked "organic".
Title: Re: DIY John Innes compost
Post by: iann on July 06, 2010, 10:22:14 PM: Hoof & Horn, slow release nitrogen source. Typical NPK 12-2-0, but not soluble. Bloodmeal is not the same. NPK approximately 13-0-0, but fairly soluble. If you use it to replace Hoof & Horn at the recommended rates then you are likely to burn the roots.

John Innes is too dense for most things in a pot, certainly for anything that needs good drainage. I add calcined moler cat litter and grit so the John Innes is less than half the resulting mix. Also limestone chips as needed.

Dolomite is just another form of carbonate, approximately half magnesium and half calcium. Weight for weight, it is slightly more effective at neutralising acids because magnesium is lighter than calcium. It is a relatively hard and dense rock, so it reacts more slowly than softer rocks such as marble or calcite. A far more important factor is the texture of the rock you add. Powders will react very quickly, large chippings very slowly. Faster isn't necessarily better, and a good limestone soil contains lots of limestone but still allows mildly acidic rainwater to provide nutrients to the roots before being neutralised.
Title: Re: DIY John Innes compost
Post by: arillady on July 06, 2010, 11:44:30 PM: Hoof and horn went off the market here years ago and on enquiry there is no manufacturers anymore and it can't come into Australia. It is a dry white grey whereas blood meal is a red brown and kind of moist.
I lament that hoof and horn is not obtainable here.
Title: Re: DIY John Innes compost
Post by: JPB on July 08, 2010, 07:25:54 PM: a lot of useful information; thanks. So I should be careful with the blood meal I have. H&H meal is not available here. Also my superphosphate is possibly triple-superphosphate, so i'm not sure how much i should add. Adding all this, today I have made a "JI-Minus Mix". Only the dolomite and no other minerals. I'll feed the plants with liquid fertilizer of choice. It is better to add nurients than to remove them, isn't it?... The loam should retain the nutrients failly well according to Roger...

Here some pics of Veronica spicata in the old mix (peat-based with sand added), and the JI-minus mix I made as a try-out a some time ago. The latter is much better as you can see.
Title: Re: DIY John Innes compost
Post by: iann on July 08, 2010, 08:48:31 PM: Loam is pretty good for supplying nutrients, but John Innes is (should be!) so sandy that it is actually quite poor in comparison to most loams. The peat adds nutrient stores for most plants, although for alpines it may not be necessary.

Superphosphate: 0-20-0
Triple superphosphate: 0-46-0

Not quite triple :) Both are the same mineral, calcium phosphate, but normal superphosphate is over half calcium sulphate left over from the manufacturing process. So use a little less than half the amount of triple superphosphate.

I think using the JI "base" nutrients works better than liquid feeds. Presumably the constant, rather than intermittent, availability of nutrients works better for the plants. Nitrogen in particular is difficult to maintain in soil with liquid feeds. You can use cornmeal (approx 2-3-1), corn gluten meal (approx 9-1-0), soymeal (approx 7-2-1), or feathermeal (approx 13-0-0) as alternative slow release nitrogen sources. Or just use a synthetic alternative :) Synthetic JI Base is available in the UK, but probably not elsewhere. Perhaps something like Vitax Q4?
Title: Re: DIY John Innes compost
Post by: Luc Gilgemyn on July 09, 2010, 09:15:36 AM: Hans, I think our "Beendermeel" (=Bonemeal) is quite close to what Rodger calls H&H !
Title: Re: DIY John Innes compost
Post by: JPB on July 09, 2010, 10:05:51 AM: Luc, at firt I thought it would, but our Beendemeel is mainly a phosphate source as is specified on the box. I was able to find a supplier of Feathermeal (Verenmeel), which is a better source for N according to Ian (http://www.plagron.nl/).

And thanks Ian for the useful info! :)
Title: Re: DIY John Innes compost
Post by: JPB on July 16, 2010, 11:02:07 AM: I have found a potful of feathermeal and I'm about to make a new batch of JInr.2/DIY.
Would you advise to crush the pellets of dolomite, superphosphate and potassium phosphate prior to mixing?

Also, the feather meal is not dry, but slightly moist (seems normal) and it is recommended to add 200g per 100 L. It seems quite a bit to add :o ???
Any comments on this amount?

Thanks in advance; you're very helpful!
Hans