Buying compost - what's in the bag?

Although this is about making Mel's mix in the UK, I have some general questions about compost, so please read on even if you're from the USA or elsewhere.....

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Timber
I almost bought all the timber from Wickes, but in the end I went to a local independent timber merchant, Tarrants Timber, and got a better price.


Vermiculite
I've worked out I need 75 litres of each of the three ingredients. I've seen a few places I can get vermiculite - here and here, and also on ebay. V4's the one I want, right? After looking around I worked out that V4 is coarse, V3 is medium, etc. I'm going to see if I can get it locally and if not, I shall get it delivered.

Peat Moss
I'm hoping to find peat moss (which is more commonly called "moss peat" over here) in a garden centre; I've just never noticed it before.

Compost
If I get 5 different composts to make up only 75L that's going to be quite a lot of wastage; I might go with only 3. I'm confused though; don't bought composts tend to have sand and grit in them, as well as peat? And if container or potting-on composts are not suitable for sowing seeds (as oppose to seeding or multi-purpose) should I avoid them? Just looking at the John Innes standardised recipes, where is the organic matter? It seems as if John Innes is already a kind of mix like Mel's mix, whereas I'm trying to find the organic matter component alone. Which type should I go for to get the purest plainest compost?

Which? helpfully mentions in one of its reviews that "Vital Earth compost is made from UK sourced, recycled garden waste and forestry by-products, and New Horizon compost is based on bark, coir and recycled garden waste" - so there's already two very different types. Any idea how to find out more about what's in compost sold as bags?

Hi, Suleika -- I'll try to answer as much as I can...

Timber -- wherever the best price is, is the best place to buy it. There are a few members who use old boards from decks, broken pallets...whatever works! You might not want to use pressure-treated just to avoid any leaching of toxic materials, but I believe Brussels has mandated that lumber an only be treated with chemicals not toxic to humans. (wish I could find that link...)

Vermiculite - your sources are fairly in line with what I paid for mine here -- but you might also want to take a look in the insulation department at Wickes/B&Q/Focus/Travis Perkins/Jewson's/Homebase, etc -- you can frequently find 100-litre bags of the stuff in the insulation department for considerably less than they charge for gardening use. (and it's the same stuff...)

Peat -- the stuff sold as peat here isn't cut from a bog, it's actually ground sphagnum moss, so there are no sustainability issues...I paid 11,45 Euros for a 100-litre bag of it just two weeks ago.

Compost -- here's where it gets a bit sticky...as everyone defines "compost" a little bit differently! Don't forget that you can also use composted manure, worm castings, mushroom compost....if it's decomposed organic material, it's probably fair game. Lots of folks have had luck with their local council, too -- many times, municipal compost (from the town gardens, what's collected at the kerb as yard waste, etc) is available as compost for free or very low cost.

There was only one brand of anything labeled "compost" here (and it was VERY pricey) -- so I bought one bag of that, and a couple of bags each of different brands of horse manure, as that's what's available here. I figure it can't all come from the same farm (and yech, it sure smelled different!) -- so it's the best assortment I could make. I think I ended up with three kinds of compost...as it's all that was available.

The book was written based on availability of American products, so the rest of us sometimes have to just substitute what we can, because what Mel recommends just isn't available outside the US...which is fine...do what you can, and don't worry about what you can't.

(Just last week, a poster in Iceland said that she substituted pumice for vermiculite, as it's readily available and cheap...whatever works!)

Hi!
I never actually said that the pumice was cheap nothing is cheap in Iceland!
I was pretty lucky because I asked my husband to buy some from his cousin (who packs ad sells it) and he didn't actually pay for it, instead he is going to find some water for the cousin or something. I needed a bit more and went to buy it today and it cost (do not tell anyone) just under 5 euros for 6 litres.

I think the problem with "compost" is that it is used in different ways in the UK, we have all that stuff called potting compost and it contains loam, peat, sand and fertilizer in varying amounts, or at least the one you mention does - no compost in it at all. Then there is the stuff that comes out of compost bins plus byproducts of mushroom farming and so on. And that is the stuff you want.
I think you could use the two you mention from Which plus perhaps mushroom compost, that should be easy enough to find. If you buy one sort that is a mixture of two types then it counts as 2.

I think 5 types is an ideal to aim for. I'm compromising a bit myself The main thing seems to be that if you use just one type of compost them it won't have a full range of goodies in it, so you need a mixture.

Okay...cheapER?

That IS expensive...the unfortunate side effect of living on an island, as even the stuff produced on the island needs packaging produced elsewhere...and machinery produced elsewhere...and the freight is never cheap.

But at least you won't have to buy it again next year.

Thanks so much for your welcome and your help. I've found the peat moss and I'm collecting compost types. I have some sterilised manure compost and some mushroom compost. I saw a bag of something called soil improver, which I thought might be like a compost, free of extra grit etc. Does that make sense? And then maybe I'll finish by mixing in from a couple of the mixed composts or multi-purpose composts. I might have sourced some vermiculite locally (at an insulation specialist) - I'll see on Monday. Then I'm all set to mix, water and plant.

After all this, I'm seeing the benefit of making my own compost - but I'm wondering how best to do that in such a small garden. Anyway, I'll have a think and post about that in the main forum.

Just to bring this question to completion...

I needed to make up exactly 100 litres of compost (total 300L Mel's mix), and the compost I bought was in 60L bags, so it wasn't too hard to calculate. I mixed up half a bag each of the manure compost, the soil improver and the mushroom compost, and then added roughly a 10th of a litre of a ready-mixed compost (which has peat etc in it). I couldn't find any other composts that were not already mixed up with light ingredients. I could tell the so-called "composts" weren't pure compost because they were much much lighter.

So I didn't manage to mix 5 different composts - only 3 and a bit - but they seemed very different from eachother.

I'll post more in my "london, UK" thread.

If you can find 5 types of compost, use 5. Use part of it to make the mix, and save the rest since every time you harvest something you'll need to add a scoop of mixed compost to the square (assuming you don't already have your own compost).
If you have a compost heap, then you can add the leftover to your heap, and it will enrich it and speed up the process.

It's impossible to tell anyway if you have really different products when buying different bags.
With so much being mass produced to order, it's quite possible to store brands from 2-3 separate stores differ only in packaging...

If it makes you feel better, somehow I missed the part about 5 kinds of compost so I only used one and I made my decision based solely on price because I am quite severely strapped financially right now. I did have a slight problem with beans looking a bit peaked but added some fish emulsion and crushed calcium/magnesium tabs that I already have on hand and they are fine now. Everything else in the bed is doing great.