News, Tips and Offers for Growers & Gardeners

Allotment Garden Newsletter

From John Harrison

Slug Pellets - Information


Following my last email, I’ve had a large number of replies about slug pellets so I wanted to clarify the situation and correct some of the misinformation on the web.

Back in 2018 DEFRA who are responsible for licencing pesticides and weed killers removed approval for metaldehyde based slug pellets. Because they hadn’t followed the proper procedures they rescinded the ban following a legal challenge.

Then they followed the proper procedures and it was again de-licenced. It was no longer legal to manufacture as a slug pellet from 31st March 2021. Onward sale was allowed until 31st March 2022 so stocks held by distributors and retailers could be cleared.

As of 1st April 2022 you can no longer buy slug pellets based on Metaldehyde. You can still buy buy the Ferrous Phosphate based slug pellets and there are no plans to de-licence these. Ferrous phosphate based pellets are approved for organic use in the UK and many EU states.

I’ve used the ferrous phosphate pellets for over 10 years now. I think they are more effective than the old metaldehyde based pellets and more rain resistant. Uneaten pellets eventually dissolve and add their nutrient content to the soil.

With the metaldehyde pellets, the dying slugs leave heavy slime trails and are often found on the surface. Ferrous phosphate just stops the slugs eating and they go off to die under the surface. Because you don’t see dead slugs, some people think the organic pellets don’t work but they do.


Firstly, all pesticides should only be used as directed.

Metaldehyde is moderately poisonous to people and animals. The pellets also contained a chemical that made them taste very bitter which would deter animals and children from eating them.

Ferrous phosphate isn’t poisonous as such. It can actually be purchased as a dietary supplement to treat anaemia, making the iron easily absorbed by the body. Overdosing on these can cause gastric problems.

To deter animals and children from eating them, the ferrous phosphate pellets also contain a bittering agent.

Ferrous phosphate slug pellets available from Harrod Horticultural.


Why metaldehyde pellets were banned

Metaldehyde has been used by farmers and growers for at least a century. In old gardening books you will find references to ‘Meta’ and mixing it with bran to make a slug bait. Just as in the garden, slugs and snails can devastate crops so farmers use slug pellets in volume. Having said that, they probably use less per square metre than the average gardener.

Some years ago a theoretical risk to wildlife from metaldehyde pellets was put forward. The theory was that a hedgehog or bird would eat the dying slug and become poisoned by the pellet the slug had eaten. As far as I know, there was no proper study showing that the theoretical risk from metaldehyde pellets was actually a significant problem in the real world. If anyone knows of a published paper on this, please let me know.

The reason for de-licencing cited by DEFRA was harm caused to wildlife by metaldehyde pellets. I know many accept that as fact but I’m not convinced.

What was a proven problem was the use of the pellets by some farmers too near to watercourses. Removing metaldehyde pollution from drinking water is difficult and expensive.

The farming industry was generally not happy about losing metaldehyde as the ferrous phosphate pellets are slightly more expensive. This may well change now the volume production is on ferrous phosphate.

Alternatives to slug pellets.

I know a lot of people don't like the idea of using slug pellets – even the environmentally friendly and pet safe Ferrous Phosphate type but…

Dr Hayley Jones, Entomologist at the Royal Horticultural Society and lead researcher said following their 2018 study: “Our study reveals that many gardeners could be wasting time and money by turning to home remedies in a bid to protect their prized plants. With the likes of egg shells, barks and mulch so far proving no discernible deterrent to slugs and snails we would recommend using proven formulas like nematode biological control if the damage is just too much to bear.”

Beer traps will catch slugs (what a way to die!) but they take time and precious beer to catch relatively few of the pests. Nematodes (Nemaslug) are usually very effective. They must be carefully applied at the right time of year when the soil temperature is above 5ºC. More information on Nemaslug available here.

I hope that clears up any confusions over slug pellets.

Quick Reminders

Before I close, a reminder that the extra £3.00 discount offer on Dig for Victory, The Monthly Guides finishes on Friday. Full details of all our voucher codes and offers are listed here.

The next newsletter will be on Wednesday 20th April, after Easter. I hope you have a good break and kind weather.

Good Growing and above all, Keep Safe


Allotment Garden

Fron Dirion, Clogwyn Melyn,
LL54 6PT