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Do you think there should be best-before dates on compost?


Using old compost won’t do your garden any favours, but sadly, we’ve found a lot of it for sale on shop shelves. It’s time to introduce best-before dates on compost – and now B&Q’s investigating the idea…

We’re very pleased to report that Britain’s biggest retailer of compost, B&Q, is extremely interested in putting best-before dates on compost packaging and help prevent out-of-date stock from hitting the shelves.

We met with B&Q recently and were told that the company is going to be conducting its own independent tests to research the issue. Tim Clapp, horticulture and garden care lead buyer at B&Q, told us:

‘We’re investigating the shelf life of compost to ensure customers get the best possible experience from any bag they buy [from us]. We’ll determine our response when the findings are in.’

The importance of compost lifespan

B&Q wants to run the testing to understand the lifespan of its compost, as it varies between different formulations. The time it takes to release the fertiliser that composts contain depends on a number of factors, such as temperature and the conditions that it’s stored in, and this accounts for how quickly it deteriorates.

B&Q is planning to explore the impact of these different factors by running independent tests over a 12-month period at the East Malling Research Centre. The retailer’s currently working on a brief for this trial and aims to kick-start it this month. It will cover the full range of composts it sells, from multipurpose to ericaceous, seeds and cuttings to containers.

How old is your compost?

As B&Q sold more than 10 million bags of compost last year and there are currently two B&Q products that are Best Buy composts, it would be a fantastic result for gardeners if the company adopts best-before dates.

We found huge amounts of old compost on sale for the third spring running when we were buying the compost for our own trials earlier this year, so it’s still very much a problem for gardeners trying to get decent results.

We’ll keep you up to date with developments from B&Q once it has completed its testing and will continue to call for other manufacturers and retailers to put best-before dates on their compost bags. In the meantime, we’d love to hear whether you’ve bought compost you suspected to be past its best.


Whilst I think it is a good idea for them to be dated ON production think perhaps it would be helpful to mention the alternatives.

This is Norfolk CC
“Home composting allows you to compost kitchen and garden waste at home. It can take between six months and one year to make compost, at which point it can be put directly on your flower beds or lawn or used in plant pots.

Why not invest in a compost bin? Please visit http://www.getcomposting.com for special offer bins.

You can volunteer to spread the message about composting as part of the Master Composter Scheme in Norfolk. Two-day training courses are held on a regular basis. As a volunteer, you can help your friends and members of your family and your local community to get composting at home.

Community composting schemes are schemes where communities volunteer to collect garden waste from local households, and then manage the material to make compost that can be used by local residents.
Buying Compost

You can buy compost from all of our 20 Main Recycling Centres.

Each 40 litre bag costs £3.50. If you would like a large quantity (e.g. in excess of 20 bags), please call us in advance on 0344 800 80 20 and we can check if the recycling centre has enough in stock. Alternatively, there are a number of composting facilities in Norfolk where residents may be able to buy compost from directly.”

The community composting projects attract over £50 per tonne which seems a splendid concept.

I make compost at home from mowings and prunings. It has little nutrition but makes a good soil improver on our heavy clay soil. Other stuff goes in a garden waste bin that the council collect and process; unfortunately they do not sell back to the public, only to farmers. I’m not sure whether I would want it though as all sorts of waste seems to go into it, including my nasty seeding and perennial weeds (like convolvulus) and food.
The idea of community compost heaps attracts me. Particularly if the local stables were involved. It would make another good source of soil improver – a lot only goes a little way.
The compost referred to here though is what I would use to raise seeds, in patio containers and grow on greenhouse plants. I buy as I need it but occasionally have a bag or two left from the end of last season. I haven’t seen any deterioration in results. I’ll be interested to see what this investigation uncovers.

Apropos compost and use by dates I found interesting and will follow the outcomes with interest and hopefully sound advice. But regarding sound advice and compost I feel I was short changed this time round on good advice by Which . As usual I consult Which advice on their best buy composts which are usually on line in early spring in previous consultations I have found such advice spot on. Not this year? I like hanging baskets I also love the lush display of flowers and trailing plants. This year Which recommended Fertile Fibre it came out top of the survey by a considerable margin. It is apparently peat free and Organic? It was also by a considerable margin the most expensive. The on line review made a point of the fact it was for container planting and hanging baskets apart from the description of the growth rate of I believe potatoes and a certain type of popular flower ( I forget which) that was the on line information. Anyway based on reliable past Which information I purchased a bag the the gentleman who I spoke to at Fertile Fibre was amicable and suggested the multi- purpose product. So fine I purchased a bag it arrived following day postage free-excellent. Problem was It was useless for hanging basket growth very little was happening. I particularly like Black eyed Susan flowers. In previous years using peat based compost they have been lush and profuse attracting lots of admiring comments. Not this year. Anyway I contacted Fertile Fibre I was told that peat free compost was like driving a super car as opposed to the usual everyday saloon etc. He gave further advice but also said I would have obtained better results with their Container Compost-after selling me General Purpose. When I contacted Which they told me that they had explained the way one should use a peat free fibre compost. Not on the website their was no mention of this. It was apparently explained in the Gardening Magazine. I do not get the magazine. So for me it turned out to be a very expensive operation in fact loosing patience I purchased planted baskets. First time I have done this. But the plot thickens (pardon the pun) Checking the Which web site I found they had published the full results of the various compost tests and the vaunted Fertile Fibre was way down the list scoring list just 42% as opposed to 88% in their recommended list? Anyway will be much more careful in looking at these recommendations in the future. I agree peat free is the way to go IF it delivers. But thank you Which for all the sound advice it gives and will hopefully continue to give. My apologies for going off the original thesis about compost but hopefully this will alert readers to the difference using PEAT FREE.

I am interested in what is happening to compost during storage to make it less effective. Are there any scientific studies?

Has Which? asked the RHS or the John Innes Centre for example for research they may have done on the life of compost, its constituents and the consequences of deterioration?

I’m reminded of the old lady who bought a grow bag. She watered it every day, but nothing grew. I have always pulled one from the pile, carted it home and used it to “improve” the flower bed soil. They do break up the soil and give it a nice colour, though it is sometimes surprising what one sometimes finds lurking in the compost. I supplement this with a couple of proprietry feeding products. The latest one has produced dramatic results on everything it touches. I agree that there should be some indication of the sell by date if it is proven that these bags lose their efficacy over time.

I like the sound of efficacious compost. Better for the Which? Hazel I suppose.

We have often bought multi-purpose compost ten bags at a time and had full and part-used bags left over for many months. We have not noticed any particular loss of quality but that is probably because we have really only used it in a general way as a general soil improver rather than a propogating medium, conditioner or nutrifier.

Very good, John. Now how about an economical efficacious ericaceous compost?

Joe McWilliams says:
15 September 2015

Being peat free is the most important step you can make. Peat releases a lot if CO2 when it is dug up. We only started using it in the second half of the 20th century and managed fine before then. Out of date compost that has slow release fertiliser in will not be as good, but will not harm. Switch to coir, wood fibres, and soil conditioner from your local recycling centre.

I think the issue is less about the efficacy of old compost but the health effects. Some old compost I’ve bought has been covered in a white mould and has given off clouds of spores when disturbed. I believe a man died once from inhaling fungal spores from old compost.

Go to this weblink and see why B&Q are investigating , they’ve been selling unusable product and gardeners have suffered!


Regrettably in an effort to abolish peat many composts do contain a lot of rubbish as a means of holding the added nutrients. I still buy peat-based composts as they are the only ones I’ve found so far that give a reasonable performance. I’m sure the “greens” will wish me burned at the stake for admitting to this. However it does end up improving the good things to eat that I grow that do not have to be shipped from all points of the globe – there is a quid pro quo.