Opinions on compost query please...

Finella_2

Due to various circumstances, we haven't been able to do much gardening over the past few years. We have started tidying out our greenhouse in preparation for growing stuff this year and have come across an unopened bag of compost. I think that I shouldn't use it to try to grow stuff but hubby says that since it is unopened it will be fine. It has been there for between 3 - 4 years. Similarly, there is an unopened bag sitting on the roof of a little shed (it was used to keep down some plastic because the roof was leaking) and I guess that it has been there for a year but in the greenhouse before that for 3 - 4 years.

I would very much appreciate your views on whether I could use the compost and actually produce veg this year - I don't want to use it and my first proper attempts at growing veg be a failure.

Many thanks!

Zazen999

What do you think will happen if you use it? Remember that compost is waste that has rotted down...I don't understand why you don't think it would be a good idea.

Penelope_Penguin

Finella wrote: »

Due to various circumstances, we haven't been able to do much gardening over the past few years. We have started tidying out our greenhouse in preparation for growing stuff this year and have come across an unopened bag of compost. I think that I shouldn't use it to try to grow stuff but hubby says that since it is unopened it will be fine. It has been there for between 3 - 4 years. Similarly, there is an unopened bag sitting on the roof of a little shed (it was used to keep down some plastic because the roof was leaking) and I guess that it has been there for a year but in the greenhouse before that for 3 - 4 years.

I would very much appreciate your views on whether I could use the compost and actually produce veg this year - I don't want to use it and my first proper attempts at growing veg be a failure.

Many thanks!

Is this potting compost I wouldn't use it to raise seedlings, as the levels of nutrients may have deteriorated, and pathogens may have started up (which can cause small seedlings to die off). I'd use it for larger plants, though, or as a soil conditioner around established plants.

Penny. x

Jack's_mummy

The bag that has been on the roof probably has had all the goodness washed out of it. The other one will have deteriorated. However, I would think it will be ok to use for veg once they are bigger mixed in with new compost. I wouldn't use it for seedlings either.

peter_the_piper

I'd only use it for a soil conditioner as over a period of time the added chemicals tend to react with each other. Whilst this does not make to compost toxic it will have an effect on the growth of your plants.

Zazen999

peter_the_piper wrote: »

I'd only use it for a soil conditioner as over a period of time the added chemicals tend to react with each other. Whilst this does not make to compost toxic it will have an effect on the growth of your plants.

Will it? I'm not being antagonistic - but packed bags of compost have probably sitting on warehouse floors for years before they even get to the stores...what sort of effect will it have? If it DOES have an effect - should it have a 'use by' date on it?

I use new compost every season mainly because I use so much, but if I got given two old bags, I'd use it for potting on - no questions.

The compost that i make gets better as it gets older, as it continues to rot down - what's different about bagged, bought compost?

Penelope_Penguin

Zazen999 wrote: »

Will it? I'm not being antagonistic - but packed bags of compost have probably sitting on warehouse floors for years before they even get to the stores...what sort of effect will it have? If it DOES have an effect - should it have a 'use by' date on it?

I use new compost every season mainly because I use so much, but if I got given two old bags, I'd use it for potting on - no questions.

The compost that i make gets better as it gets older, as it continues to rot down - what's different about bagged, bought compost?

Gardeners' World had a campaign on this some years ago now IIRC, don't know whether anything happened Totally agree that seed and potting composts should have use by dates :T

There's a big difference between "garden" compost and "seed and potting" composts. The former is used by most gardeners as a soil conditioner, though a few make their own seed/potting composts from that.

Seed and potting composts are made to a recipe (often the John Innes one ). They contain precise amounts of fertilisers, so will deteriorate over time.

HTH, Penny. x

Zazen999

Penelope_Penguin wrote: »

Gardeners' World had a campaign on this some years ago now IIRC, don't know whether anything happened Totally agree that seed and potting composts should have use by dates :T

There's a big difference between "garden" compost and "seed and potting" composts. The former is used by most gardeners as a soil conditioner, though a few make their own seed/potting composts from that.

Seed and potting composts are made to a recipe (often the John Innes one ). They contain precise amounts of fertilisers, so will deteriorate over time.

HTH, Penny. x

I'm aware there is a difference and different recipes - I'm interested in the effect that it would have, particularly when bags have probably been sitting in warehouses for years - and we are only talking a couple of years in this instance. 10 years, possibly - but a couple?

peter_the_piper

Zazen999 wrote: »

Will it? I'm not being antagonistic - but packed bags of compost have probably sitting on warehouse floors for years before they even get to the stores...what sort of effect will it have? If it DOES have an effect - should it have a 'use by' date on it?

I very much doubt that compost stays on the warehouse floor for years, its not profitable for stock to sit idle for too long.
We had a discussion with a compost supplier and its well known that chemicals interreact in the presence of moisture though it takes more than a year or two to have an effect. I've no problem with use by dates providing they are for technical reasons and not just marketing.