I have come to the understanding from reading here in the Non-Organic compost threads that when a bag of compost is purchased it has a finite shelf life.
i often make use of the 'buy 3, get em cheaper' offers at the likes of homebase and b&q when buying my compost but i never need to use that much during one grow, so i keep the extra bag or so stashed untill the next run.
My question is: How long is it advisable to keep a bag of MPcompost for before it becomes 'out of date' ?
and also, what are the signs that the compost may have become unusable after being stored unopened for a period of time?


thanks.

I've done the 3 bags for a tenner deals before and used them on the next grow and they were fine. They may have run out of nutes a little quicker, although i wasn't sure as i was growing different plants/strains so they might have just been hungry buggars. I'd assume within 6 months there wouldn't be any significant difference.

cheers KC, i get through them all over 6 months, i guess its down to how long they have been sat at the garden centre though.

anyone know if the ph of old compost can fluctuate causing nutrient lock out?

and one last question, if the MPcompost smells good/fresh then can i assume its good to grow in?

a while back i bought a few of what i thought were fresh bags of homebase own brand MPcompost and it smelt in my opinion of petrol/fuel, in fact it stunk the room out the plants were in . The plants after being potted up in it quickly showed symptoms of iron deff. it was corrected easily with a foliar feed of maxicrop+iron, though it did put the progress of the plants back a week or so. ever since i have been checking the compost i get by smelling it before potting up in it.

Well, i'm just about to start on 2 bags of organic compost that ive had for about 6 months...

Hope to fuck it's ok cost me £40 odd and I didn't get round to using it till now

If you get yellowing because the compost is a bit dodgey, feed them 0.5ml per 1L. They shouldn't burn from that if your soil is out of nutes when your still in 3" pots. Should keep them from yellowing in 3" pots too. Better off getting new compost man.