/ Food & Drink

Twisted tomatoes – is weedkiller in compost to blame?

Veg grown in compost bag

Have you had problems with plants grown in bought compost this year? We’ve heard stories that some tomatoes have shown twisted, distorted growth and had to abandon a trial of potatoes grown during our trials.

Recent media reports have suggested that clopyralid, a lawn weedkiller, may be present in composts. It’s thought that it may have got into mixture via council green waste, an ingredient in many bagged composts. Clopyralid contamination has already been a problem in the United States and New Zealand, so could the same thing be happening here?

The Sun’s Peter Seabrook has levelled criticisms at peat-free composts in particular as some contain green waste. But green waste is likely to be an ingredient in many composts, both peat-based and peat-free.

Herbicides affect garden growth

Now it wouldn’t be the first time that herbicides have affected gardeners – aminopyralid, a herbicide used on pasture, recently found its way into manure and then onto people’s veg plots, killing sensitive crops.

The Waste & Resources Action Programme (WRAP) is looking into the suggestion that clopyralid has got into composts, but points out that plant problems can be caused by a number of other factors, including viruses and over watering. It also points out that a compulsory test for herbicide contamination is carried out during the compost manufacturing process.

Digging the dirt

I wonder if gardeners know whether it’s safe to put grass clippings containing clopyralid on the compost heap or the council green waste. Labels on lawn weedkillers containing clopyralid (such as Evergreen Lawn Weedkiller, Verdone Extra and Vitax LawnClear2) are ambiguous, but in essence, any grass clippings that have come into contact with clopyralid should be put in the waste bin rather than used on the heap or put in the green waste bin.

I’m worried that manufacturers don’t spell this out for gardeners. Also, many people pay companies to care for their lawn, often using chemicals, and may have no idea that their grass clippings should not be put on the compost heap.

We’re keeping an eye on the situation and will let you know if we learn anything more. The compost that affected our trial is being analysed, and we’re also awaiting the results of our latest compost trials due to be released early next year.

In the meantime, if you’ve had problems with compost this year, we’d love to hear your experiences to help inform our findings.


I had not appreciated that clippings from treated grass should be treated differently, but this does not surprise me. If we assume that compliance is likely to be poor then why are these products licensed for use? Many gardening products have been withdrawn over the years and these weedkillers could be the next candidates to get rid of.

I try to minimise the amount of chemicals I use in gardening. How I tackle weeds on the lawn is to put a small amount of weedkiller in the centre of dandelion etc. rather than treating the whole area, most of which has no weeks. Doing this four or five times a year keeps the grass weed-free and a box of weedkiller lasts years.

Donald F Lee says:
24 October 2012

About this time last autumn I planted sweet pea seeds as usual and got a very poor germination rate. As it was old seed I thought that this was the problem so bought new seed. This new seed and seed collected from the remains of last year’s crop were planted in the same commercial compost and again produce a poor germination. I kept the pots with some plants in them but the plants just did not grow. Come February I planted seeds of all three seed batches in material sieved from my compost heap – excellent germination! When I tipped the earlier plants out the roots were at most only a couple of cm long, very branched and kinked. Unfortunately I had not kept a record of the brand of the comercial compost.

Kate V says:
26 October 2012

Like a lot of gardeners my plants struggled with this summer’s poor weather and low sunshine levels. I have two large window boxes which I re-plant each Spring and then again the following Autumn. I used Westland Container & Hanging Basket compost and planted antirrhinum(bought as young plants), mesembryanthemum (grown from seed) and one hebe ‘Heartbreaker’ in each box around about May time. I also added – despite there already being nutrition in the compost – slow release pellets in plug form which I have done for many years past, with no detriment to the plants. The boxes face south but my plants really struggled, despite being in the best position possible to benefit from any good weather.
For the Autumn planting, done towards end of August, I changed to Miracle-Gro Pots & Containers with moisture retaining granules compost. I can’t believe the difference in growth of the plants. The hebe was left in the box with its roots undisturbed, but surrounded by the new compost. The plants are twice as big as they were at the end of the Summer with violas, helichrysum seritonum, silene Druits variegated and sedum Rose Carpet surrounding the hebes and all are doing extremely well despite the weather not having improved. I can ONLY put this down to the compost. I also grew some viola seeds bought at Chelsea using the first compost. I got good germination, but after that it was a struggle to get the plants going. A few grew about 6 leaves and then just sat there not growing. I then tried them in the new compost and they have improved no-end. The antirrhinum were split up and planted in the garden where they are now re-flowering, something that didn’t happen in the boxes. I will not be buying Westlands compost next year!

Alan Preece says:
29 October 2012

I bought 3 bags (3 for £10) of Miracle Gro general purpose compost and planted out tomatoes, courgettes, cucumbers and peppers which were healthy seedlings grown from new seed. There was just no growth at all in compost from two of the bags, so I potted up some in a much more expensive (Forest Gold) compost using the left over seedlings. These rapidly overtook the first plantings and gave some yield albeit a bit late and into lousy weather – even the ones I put outside did better than the first plantings in the greenhouse, and the only cucumber plants to produce anything were the two I put outside, and one I rescued and replanted in the new compost. I dumped the rest of the Miracle Gro compost and next year will fork out for the more expensive compost – it has a much nicer texture anyhow, whereas the Miracle Gro (which I used happily in the past) was like coarse fibrous chippings.

Gary Hughes says:
30 October 2012

Having read the article in this month’s Gardening Which the symptoms described, particularly in respect of distorted tomato plants, exactly match my experience.

I planted a number of varieties, including Orkado, recommended as a result of last year’s growing trials. I used two different composts and, particularly in the case of Orkado and Marmande, I was therefore able to directly compare the results of growing in each compost.

The differences were so striking that the plants looked like different species rather than different varieties. One group of plants grew well, or as well as could be expected in what we laughingly referred to as our summer, whilst the others grew very slowly cropped poorly and the foliage was very badly distorted.

The resulting plants and fruit were so unappealing that I suspected weedkiller damage and, whilst I grew on the plants for comparison purposes, we did not eat the fruit.

The two composts I used were:
J Arthur Bowers Multipurpose.
Westland Multipurpose with added John Innes.

Unfortunately I didn’t make a note of which was which so I cannot identify the compost that gave rise to the problems but maybe, if they get enough feedback, Which can do this by a process of elimination.

Dave Allan says:
3 December 2012

I have a gardening column in The Herald’s Saturday magazine and my firm, ASK Organic, has been in partnership with Scottish Borders Council since 2005, giving home composting advice to householders in the local authority area.

I have looked into the clopyralid issue and published my views in my column and on our website. Essentially, the synthetic chemical, clopyralid takes at least 18 months to break down in any composting process. Householders using the chemical, and most others, are told not to compost the first 2 or 3 batches of grass clippings. How safe are later clippings? Some companies that provide lawn care services refuse to give details about the chemicals they use.

Apart from the damage to plants and wildlife, the chemical may be brought indoors on children’s hands and feet or on pets’ paws.

The chemical is banned in some parts of the world. It surprises me that the U.K. government hasn’t adopted a similar policy. The solution meantime is for householders not to use lawn fertilisers and herbicides. If they insist on doing so, they should not compost any grass clippings and should consign the clippings to landfill, never to a green waste collection. Gardeners should be responsible about this as Local Authorities should not have to, and probably cannot, protect their green waste from this kind of contamination.

David says:
6 January 2013

I too have suffered with poor material and traces of herbicides in growbags. In 2012 I had one growbag which produced stunted growth. Other growbags with the same batch of plants were quite normal. I wrote to the manufacturers J Arthur Bowers and complained of foreign material in their growbags. Their response was exactly the same as when writing about previous problems with foreign objects found in their bags. Their explanation is that these foreign objects come from their suppliers of compost materials and that they are making changes to the selection process and screening methods. They also suggest that I use Traditional Potting Compost in future rather than growbags since this is made up of 100% professional grade peat and has nothing else added other than some nutrients.

J.Mosse says:
8 June 2013

I have just found the same with New Horizon Organic compost ,in which my lettuces and beans failed.The beans that did come up were distorted.Cabbages were fine. That would be typical of clopyralid from lawnmowings or aminopyralid from farm manure. Organic????
Dow chemicals who produce these poisons say the labels are explicit as to preventing this from entering the recycling chain. Yet we have found that our horses manure has caused severe herbicide damage to cucumbers I grow in hotbeds , and this has to have come from haylage or straw which in theory should never have been offered for sale if treated.
To be stuck with valuable manure that we cannot use and be unable to sell our crops till this is sorted is heartbreaking.
Traceability is impossible as fodder merchants have little idea of which batch comes from where.
I could spread this onto my fields, but I would lose the wildflowers.My fields would start to look like the green deserts I see too much of round here .no buttercups, no butterflies., no birds. These herbicides kill clover too, so increasing the need for nitrates. This is crazy.Why on earth cant people appreciate the beauty of speedwell and clover in a flowery lawn?
Looking at gardeners forums it is clear that this is a huge problem . It is time to ban these herbicides altogether.

I have a bag of Arthur Bowers Tub and Basket compost ‘with added water storing crystals’, bought around the year 2012. It has killed every single plant that came in contact with this ‘fancy’ poison.

I still have a half of bag of this thing, because I do not know where to dump this poison.

Roger says:
21 June 2015

J Arthur Bowers grow bags are most definitely contaminated with something. Earlier this year I bought 11 grow bags and planted 33 tomatoes both inside and outside my greenhouse. Of the 33 plants only one flourished. All of the others just refused to grow and the leaves became dark in colour. Tomatoes grown from the same seed but in different compost all did well. I have e mailed William Sinclair Horticulture LTD at info@williams-Sinclair.co.uk with photographs which clearly show the problem. I suggest others with the same problem do the same.

Richard says:
30 June 2015

My kale, chillies and achimenes all grew distorted and very slowly in Westlands john innes. Not just a waste of time and money but now we have to dispose of the useless stuff. At best it goes to landfill. Nevr again will I buy anything from westland.

Chris Nother says:
19 June 2016

A few questions that need answers:
– If clopyralid contaminated commercial produced compost has caused serious problems for gardeners who is liable?
– What about health risks in eating vegetables that may survive and mature but still contain clopyralid in their tissue, shouldn’t the government issue warnings and all commercial products that utilise council composting scheme materials be withdrawn from the market until thorough checks are undertaken?
– Should the council composting scheme be postponed until such time that the products they use in the making of the compost can be adequately tested?
– If it is found that clopyralid is found in commercial products that should have been tested by the manufacturers, should the manufacturers be prosecuted and forced to compensate the affected public?
– What should gardeners do if they have used products that have later been shown to be contaminated?
How long can clopyralid remain in the soil and possibly affect future crops?

Mike D says:
8 July 2016

For the past few years I have used Levington tomato grow-bag compost for growing my tomato plants.
This year I have standard tomato plants solely in grow-bags and grafted tomato plants in ring culture pots filled with grow bag compost and standing on a bed of another proprietary compost .
Both sets of plants developed leaf curl. This has caused me to doubt my techniques which have been good practice in the past.
However the ring culture plants have partially recovered which I attribute to the roots having passed through the pot filled with Levington grow bag compost into the proprietary compost bed. The plants solely in the grow bags have serious leaf curl and will need destroying.
Is DEFRA responsible for setting the quality control standards for agricultural products and if so why has this happened? Or is the quality uncontrolled. How on earth do you find out?
Could Which please publish a list of contact addresses for the main suppliers so the problems can be fed back to them?

Jan H says:
25 August 2016

I have lost my entire crop of Tomatoes, Chillis and Cucumbers in my two large Greenhouses this year, all grown in Levingtons Grow bags. All plants have shown classic Aminopyralid damage from the contaminated compost. Levingtons have now admitted by phone, that they have had a problem but have not said what it is or put it in writing, but they have offered me a paltry sum of money to cover the cost of replacement plants and Growbags. They have not offered to compensate for loss of crop, wasted labour and disposal of their contaminated product. Neither have they offered an apology. An appalling response. They are selling poisonous products to the public for the production of food. What can we do to stop this?

Pam Payne says:
2 September 2016

We have had a very disappointing crop after growing tomatoes in Levington’s growbags. Distorted tomatoes and leaf curl. We have eaten them but wonder now if we shouldn’t have .Should we worry?One plant grown in a different brand has not resulted in leaf curl.What do we do with the soil contents of these bags. We can’t just put them on the garden.

Sandra Mason says:
23 January 2017

The tomato plants I grew last summer had distorted, very curly growth and I used one spare growing bag to fill up a large trough that I planted with bulbs and wallflowers. The wallflowers are not thriving. How long does this chemical remain in the compost?

Chris says:
26 May 2017

This is ongoing and getting worse looking at the dates of posts.
Westlands is by far the worst compost I have experienced thus far. ALL my basket plants and tomatoes have either leaf curl, stunted growth or no germination. Roots are mere centimetres and as stated, severe stunted growth if any at all. Severe lack of growth of flowers has only green and practically no flowers, the only flowers so far are a few pansies that are struggling, this is really bad. This is legal destruction of nature, is there no rules to the contamination of composts?
Looks like I am going to have to find a place in my smallish garden and dig up any soil I can and use that instead next time, wasted so much money on seeds that fail in terrible compost.

Jan H says:
12 June 2017

Levingtons are selling contaminated Grow Bags again this year. Ironically I bought 20 of their Grow Bags with vouchers that they gave me as part of my compensation for last years lost crop. I am now in the process of losing all my crops again except for those which I planted in my homemade compost which are all growing normally. I would urge anyone with twisted, distorted and deformed plants to shout about it. How do we get this stopped? We are being sold poisonous compost to grow our food in. Who in authority can put some weight to this and get it stopped? I am witnessing 5 months of work wasting away, all that labour and a lost crop again…….

Jan a consensus of gardening websites that posters sent away the peat-free grow bags containing recycled ingredients including bindweed+dock roots via local councils to a lab for chemical analysis they came back as containing Hormone Weedkiller. I am not saying yours contains that but the symptoms of many of the gardeners who posted all match up. accelerated growth /spindly leaves /resembling fern growth after 3rd node ,deform and do not grow/ flowers distort /fruits misshapen /lead shoots become club-like . This makes me angry as I can guess the original supplier of this NON – natural weedkiller , so much for saving the planet but kill the population . Peat has kept alive 1000,s of Scots who lived in poverty in the Highlands+ Islands , living in 1/2 room crofts in poverty , have none of you seen the films from the early days up there ? No electricity / no gas/ nothing but a hard , life shortening existence so I have little sympathy for those wishing to deprive the very poor of actually Living on this planet. Humans first -eco second. If it kills bees /insects then it is harmful to humans and I just happen to have the info on the illnesses that can happen on an accumulation of this product when it is ingested over decades but as with all too big to fail/fall companies the EU is still allowing it to be used –massive lobbying ( by you know who ) .

It would be interesting to know how well the garden waste that local councils collect from many householders is treated and composted. There is no knowing what it might contain. I doubt if the councils carry out the composting themselves so it probably goes to special plant with no public identity which are supplying the resulting product to the major compost ‘manufacturers’. What tests do they carry out? Grass cuttings should not be composted for several weeks after treating a lawn with weedkillers or other chemicals; how many householders diligently follow those rules? Vast quantities of general purpose compost are purchased each year and the entrances to supermarkets are stacked high with it. It’s a multi-million pound industry but it keeps a very low profile.

Well that was an interesting tour of British recycling /gardening websites in Britain John over an hour checking up and your right pretty secretive , you have to get behind the eco advertising and that includes the “Friends of the Earth ” . All council recycling plants are not equal and there is a big difference between the high quality smaller green recycling depots and larger ones . It seems the good ones have three classes of the product and only 25 % of it is suitable for actually growing plants , second class is for improving heavy clay soil and the third lot —land infill . The bad ones ? well lets say they are not as discriminating , plastic, tin foil , you name it is included in the (non) finished product . In relation to Jan,s post tomato plants are the chosen plants that are used to test for herbicides , but as per usual the tests are only carried out infrequently -so-quote- so the risk of herbicides being present cannot be removed completely but also quotes the London Eco Park as-passed every herbicide test up to this date -so the risk is small-unquote . A lot on London here – quote chemical residue in compost could be a serious issue , in urban areas (London ) we are recommending not to eat fungi from the wild too often as heavy metals-cadmium/lead may be present —we have had neonicotinoids (highly toxic/persistent ) in use for 10 years are they being tested ?? — consensus –NO ! beekeepers beware . Conclusion ? its down to money -isn’t it ever ? and all this ballyhoo about “Ecoism” has allowed very bad practice to proliferate, this was an “eye opener ” to me . I got some of this from an article on London Waste EcoPark Wendy+Tom who run the place so they are being honest also other websites like Vertical veg.org. I have seen the photos of how its done and supposedly segregated into different groups but only some do that.

Patrick Taylor says:
13 June 2017

Very useful info to know. And I sympathise with your anger and distress.

Given that the garden centres are also selling what are called bee -friendly plants but are actually contaminated with very bee unfriendly chemicals [ 80% of those tested] there does seem plenty to be worried about.

My wife does buy commercial composts and I will try this year [ ne w bigger garden] to make some decent compost. However looking at the no dig methods where large amounts of mulch are used on the growing beds this may be the best way to go to grow clean vegetables.

There are several good videos both UK, US and Continental on the no-dig methods. Garden Organic is a useful resource.

To back up what you said on DIY Patrick , every gardening website , without exception insist if you want 100 % organic then make it yourself , as long as you dont spray your garden with chemicals . Dont sweep up leaves, if left, the worms pull them into the soil . As John has mentioned when you make your own compost leave it till it is completely ready to be used/keep turning it , dont be too hasty ,this is also echoed on gardening websites. While it might upset non gardeners the gardeners best friend is the humble worm – aerates the soil, pushes good soil up to the top through its body, called castings , it pays to put worms in your garden to improve it.

Heather Anderson says:
13 May 2018

For about thre years with grow bags and general purpose compost and house plant compost I have been reduced to tears. Mostly Westland and levington. I have had leaf curl, very little root development, and ended up throwing everything away. Some plants eventually seem to break through and get going. I have green fingers but I have lost an ancient family asparagus fern that I was entrusted with 100 years old and used for all our weddings, after repotting. It came on as usual turned yellow and died. I also nearly lost an old large bonsai yew, but got it out washed the roots and used garden soil. It is now recovered except for a few bare patches. A large plumbago is trying to shoot but stalled. I am afraid I will lose that too. Where I threw out the old stuff on the garden and dug it in, that area is now dead. Nothing will germinate there this year, or tries and stal and collapses. Even a patch of sunflowers! It is so disheartening to a keen gardener. Growing things is what keeps me going! I had never thought of the soil as really an issue till I read these comments, I was blaming my self or the season and so on.

I’m sorry to hear this, Heather. The safest solution will be to make your own compost, providing of course that you don’t use weedkillers etc. A friend who is well aware of this problem avoids the well known brands and buys compost in plain white sacks from a local supplier. I don’t know what it is but it works fine, though is quite expensive.

Our local council was offering free compost recently but I’ve no idea what that might contain.

I sympathise Heather as a lover of ferns and fern growing I found that natural earth suites them best . I have a semi-wild garden leaves are left on the soil or if elsewhere
I sweep them onto the earth the soil loves it , the worms love it and the birds love the insects under the leaves especially Blackbirds . Not one of my ferns has died and some are about 3 feet or higher not only that they are so happy the propagate freely . Asparagus fern is not a troublesome plant to grow so the contents of the “grow ” -LESS bag must have been poisonous to the plant. You should see the complaints on American Consumer Affairs.com website on “Miracle Grow ” peat – it killed my tree fern is just one – white bugs came out of it– it should be called “miracle die ” . One star out of five- again and again . quote-plants I have had for 40 years are dying – 125 year old Christmas Cactus dead — all new posts as of spring -2018 – after investigation – cause ? FUNGUS GNATS – they dont tell you about them.