Managing slugs without chemicals

As some readers know I share an allotment (half plot) with friends in Wanstead (East London). We have a slug problem! Over the last 18 months I have researched, and tested, a range of ways of keeping slugs from eating our plants. We run the allotment on organic and biodynamic principles so we do not use slug pellets, or other chemical methods. We don’t want chemicals in our food, or the soil.

Our allotment

What are slugs?

This is the common name for any apparently shell-less terrestrial gastropod mollusc. There are lots of different species, some of which are not even that closely related.

One of the culprits!

Slugs’ bodies are made up mostly of water and, without a shell, their soft tissues are prone to drying out. They must generate protective mucus to survive. Many species are most active just after rain because of the moist ground. In drier conditions, they hide in damp places such as under tree bark, fallen logs, rocks and man-made structures, such as planters, to help retain body moisture. They are actually very useful as they eat dead and decaying material. What makes them annoying to humans is their love of green vegetables and soft fruits!

The options I have tried;

1. Beer Traps

I use a small pot that is water tight. This could be a cut up plastic bottle, or large yogurt pot. Then dig a hole and sink it in, pushing the soil right up to the side. Filling a third with beer and a third with water. Matt (my allotment buddy) made covers for the beer traps, with sticks and cut up large water containers. This will help the beer not get further diluted with rain water and reduce evaporation in hot weather.

Beer trap with cover on top

Beer trap with cover removed

I empty the pots, and refill, every two weeks from late spring to autumn. On the weeks I am not emptying them I give them a water top up, depending on how hot it has been.

Warning; the smell when emptying can be quite pungent! I put the resulting mixture on the compost heap. If any of them are still alive then at least they have a lot of food to eat so won’t leave!

2. Egg shells

We save egg shells from both our homes, crush them up and sprinkle around the base of the plants. The nutrients from the shells are also good for the soil.

Egg shells liberally sprinkled!

3. Coffee Grounds

We save coffee grounds from our homes, and I sometimes pick them up in bulk from a local independent coffee shop. Most shops are happy to give these away to gardeners as it reduces the amount they are paying for waste collection. I just sprinkle around the base of the plants. These also contain great nutrients for the soil. I don’t separate the filters as we use unbleached one, they will break down in due course.

Coffee grounds helping protect a baby courgette plant

4. Foil / copper rings

If your slugs are especially persistent, like ours, foil / copper collars may be helpful when plants are small. And for some brassica vegetables (eg cabbages / broccoli) they will need protection for most of their lives.

The copper rings look smart, are reusable, and easy to apply, or move around the allotment. However they can add up in cost if you need all of your baby plants to be protected!

Making a foil collar is easy and cheap. If you are careful you can reuse the foil. They are a little more fiddly to install.

I rip off a length of foil, depending on the size of my plant, fold in half to give some rigidity. Then crunch it up, and flatten it out again. This is important as its the crinkly-ness that the slugs don’t like. Wrap around the plant, fold the edge together to make a ring. Ensuring that the bottom of the foil has earth piled around it firmly, both to keep it in place and to stop slugs getting underneath. For extra stability I incorporate a small stick.

Copper rings protecting broccoli

Foil collars protecting sweetcorn

5. Plastic bottles / fruit punnets

Plastic bottles and fruit punnets can also help keep the slugs off seedlings until they are big enough not to be lunch. I put them over as I sow seeds, with soil pushed against the sides and sticks to ensure they don’t blow away.

We don’t buy water, or fizzy drinks in bottles, but our allotment friends neighbours do, in large quantities. So we have a constant supply!

Upcycling water bottles

Fruit punnets protecting salad onion seedlings.

6. A pond to attract amphibians

Natural predators of slugs include frogs and toads. Encouraging these amphibious friends will help keep the population under control. Apparently 1 frog can eat 100 insects / slugs in 1 night!! Matt is currently digging out a small pond space. He will line it with an old hot water tank he found. We will of course ensure it has varied internal levels to allow creatures to get in and out easily, and plants for insects to live in.

The site of our pond to be!


Let me know what you have tried and what has worked?


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