Has commercial bagged compost become rubbish?

[quanglewangle]

This post is about commercial bagged compost, not the home brewed stuff. I do make my own - I am fortunate enough to have access to grass-fed cow manure that composts nicely. However I also use commercial bagged compost at times when I need sterile, weed-free media such as for seed sowing and greenhouse beds.

OK - Has commercial compost become rubbish?

I think it has.

I know what composted wood waste looks like because we buy a boot-full now and again for mulch from a local organic waste recycler. They are upfront about it taking a year to decompose and don't sell it as compost.

Careful separation of commercial compost on a saucer leads me to think it contains a lot of wood waste and sand. It doesn't behave like compost used to: water sits on top, it separates into fiber and sand, and stuff simply grows less well in it.

I realize that there are pressures to reduce peat use but compost makes really need to be more transparent about what they are selling and perhaps even put in some development to make the non-peat components of their product more peat like.

[nick the grief]

Human had so many complaints they actually went back to their original ‘Recipe’.

we (gardeners) fell for the advertising from the big companies I think. If you want to reduce your peat use then Go back to good old John Innes ... 7parts loam 3 parts peat 1part sharp sand. I used to mix my own when I was growing my chrysanths. It as one of my winter jobs and the add the appropriate fertilisers when I needed it - I still think it grows better plants

[quanglewangle]

Making your own is easy enough until you get to sterilisation. Big fire, corrugated iron sheet, turning while hot, and so on. I've done it but would rather not have to: horrible job.

[burnie]

The quality of commercial compost has been poor for years in my view, when you sieve it almost half is poorly composted, I think there's a lot of soil conditioner from the council tips mixed in it, it certainly hasn't got hot enough to sterilise it, I often get weeds growing in seed trays.

[Peteyd]

It might just be me and the way i use it but i find shop bought compost gets incredibly hydrophobic when it dries out, to the point where you have to float the pot on a bucket of water for ages just to get it re-hydrated. That's not something i find when i use homemade stuff (although i don't make a huge amount anymore due to space limitations)

[quanglewangle]

A drop - literally a drop - of washing up liquid will counter re-wetting problems.
I actually don't think that's a problem with recent formula changes: pure peat exhibits the same behaviour.

[ameno]

You are generalising far too much by saying "commercial bagged compost is bad". It varies hugely by brand, because the composition varies hugely by brand.
Some are indeed hopeless, but some are excellent. You just need to buy the right brand.

Peat-like peat replacements are also already well developed, it's just that they are not necessarily cheap, so cheap brands of compost don't use them (the main good peat replacements are coir, finely shredded composted bark, and what is known as "expanded wood waste", which is where wood chips are blasted with high pressure steam, which separates them out into their constituent fibres, creating a fluffy, absorbent material).

If you are interested, this yea'rs Which best buy composts for seeds and young plants (container compost review comes in April) are:

Seed sowing (descending order):

-Thompson & Morgan Incredicompost (80% peat)
-Melcourt Sylvagrow with John Innes (peat free)
-Westland New Horizon (peat free)

Normal Melcourt Sylvagrow compost and Homebase Peat Free Multi-purpose also scored well for peat free, but missed out on Best Buy status.
Levington John Innes Seed Compost, Wilko Sowing & Cutting, Champion's Blend Multi-purpose, Levington Seed & Cutting, and Homebase Multipurpose also all scored well for peat based (peat content varies from 50-80%), but not enough for Best Buy.

Raising Young Plants (in descending order):
-Melcourt Sylvagrow Multipurpose (peat free)
-Thompson & Morgan Incredicompost (80% peat)
-Westland Multi-Purpose with John Innes (45% peat)

The following also scored well but missed out on Best Buy (in descending order):
-Homebase Multipurpose (50% peat)
-Wilko Multipurpose (50% peat)
-Wilko Indoor/Outdoor Potting Compost (50% peat)
-The Greener Gardening Company Happy Compost All Purpose (peat free)
-Thompson & Morgan Incredipeatfree
-Homebase Peat free Multipurpose
-Levington Seed & Cutting (60% peat)

I should also note that Westland New Horizon did very poorly for raising young plants, despite doing very well for seed sowing. Lack of nutrient was thought to be the problem.

Personally, I've been buying Melcourt Sylvagrow for years now. It consistently either gets Best Buy or just falls short of it, and I have been very happy with it. It has excellent texture and plants always grow well in it.

[quanglewangle]

Really useful post ameno thanks.

I accept the charge of generalization. Ouch! I suppose I fell into the traps of buying on price, and then assuming all composts were the same.

[goosander]

With not being able to get my usual compost my wife got me some from well known brands. [will not mention names] . I had to pot on the same plants in to them. The results were amazing. My usual compost came away well as usual. Some of the other plants just died and others made very little growth.
This is not new as I remember reading an article in the Horticultural Trade Journal many years ago complaining about the difference in the various brands. It was when they were trying to find a way to save the peat bogs.
Bob.

[burnie]

Due to the lockdown last year I got delivered what was available at my local GC, it was Westland and it wasn't great for potting on, ok for the chillies in big pots, there lumps wood in it which I thought was a poor show.