How long will compost last?

I am contemplating getting a pallet load of MPC which I will split with some friends. I can store the bags under cover so they will not get wet. Do you think I am pushing my luck to expect it to last say 3 years.

 

The fertiliser element lasts 6 months if you're lucky It makes a big difference storing it in a cool, dry, dark place, though.

 

The added fertiliser is only likely to be affected by damp, and unless it is actually washed out ,will remain .

 

So are you saying it should be ok if stored under cover on a pallet to keep off the ground it should be fine. I have an old field shelter which is pretty well bone dry but open to the air. It is perfect for storing logs so hopeful the compost would be ok.

 

Three years is long time, just wonder if it might go sour, I've never kept any that long myself.
If the issue is just one of the fertiliser disappearing then it's easy enough to add some more when the time comes.

I just wonder what chemicals old damp fertiliser turns into.

Do bags have a use by date on them, I don't think they do?

 

I have used some Jack’s Magic some years ago WHEN it was good which was about 2 years old and it was ok despite being quite wet when I bought it. It was stored under cover so did dry out a bit. Most of the compost would be used for seed sowing or in tubs where I would be feeding the likes of tomato feed anyway and be augmented with manure mixed at the bottom of the containers. I can get delivered (delivery a bit dire as I live in Scotland) a pallet load which works out at roughly 7.5p a litre delivered for decent stuff not recycled god knows all what. That is considerably less than buying a single bag (almost half the price) and I am in the fortunate situation where I can store a pallet load out of the way and under cover. I’m tempted unless I might live to regret it!

 

Maybe you should just grow more plants, that way it won't hang around for so long.

 

Oh haha I already stuff my 8x20 ft greenhouse with so many plants that I need a machete come about August to get into it. In a good season, unlike last year I am usually accosting folk walking down are road and demanding they take my excess cucumbers!

 

I have a bag of J.I. Seed compost that is 4 years old, I mix with equal parts
of Coir & sifted garden compost. I've had no problem, well apart from not
getting enough Sun in the growing season. Fingers crossed for this year.

 

Straight fertilisers do not appear to degrade with storage, just go solid !
Dampness may cause pva encased granules to release the contents but unlikely to do so if dry. Similarly, organic materials do not decay unless damp.

 

The way I'm looking at it is it will be damp, it might appear dryish, but I've never bought a totally dry bag of compost and TBH I dont think I would want to, rewetting totally dry stuff is not what most people want.

Anyone who has kept fertiliser in a jar over winter will know it attracts moisture, even keeping them in out buildings doesn't keep them dry with high humidity over winter.
For that reason I always overwinter left over fertilisers in the house.

 

The standard advice is always to buy fresh each year as it degrades, but it's never been totally clear to me in what way that happens. I agree it may attract moisture from the air.
If compost is bone dry it can be re-wetted by adding a little wetting agent to the water. If you just use plain water it will tend to drain straight through.
I guess the biggest difficulty is that you won't know it's gone "off" until your seeds/plant don't grow.

 

I have stored a couple of bags for 2 years + and on opening it was far far better than when freshly bought. I say that because nowadays it seems to be mostly wood/fibre and the compost actually improves by leaving it some time. The only problems I hear about are with new compost burning the seedlings because it wasn't properly ready.

You can just mix a little new compost with old or sow your seeds in new compost on top of old.

 

I have now been quoted an even better price for a pallet so it is a no brainer. The only snag is the bags are 75ltr so no doubt I will acquire a hernia.

I find it incredible that so much forestry byproducts are now in composts. Years and years ago I learnt not to put manure which had shavings bedding incorporated in it anywhere near plants for a good 2 years as it would burn plants far less use it for sowing seeds. I very much doubt commercial growers will accept the withdrawal of peat without one hell of a fight. It will be us amateurs who will have to put up with dross unless we source alternatives which currently are not that readily available without some research.

 

I was always under the impression that un rotted wood shavings absorbed the nitrogen in the rotting down process which could be why growth is poor in lots of the peat free stuff.

Burning of plants and seedlings I thought was more about using fresh manure which contains ammonia.