The problem with slug rings
Your young cabbages are being nibbled by slugs…
… You need a solution.
Among the countless options sold online – most of them barely effective – you turn to slug rings (plastic, or copper).
Let’s take a look together at an overview of slug rings, their pros and cons, and the possible alternatives, and finally ask ourselves whether this choice is a good idea, for you, and depending on the context.
The two types of slug ring: an overview
There are two kinds of slug ring currently available to buy:
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Plastic slug rings (with a flared collar): they have an outward-sloping collar that makes it harder for the gastropods to climb over. They are fairly tall (around ten centimetres). They cost roughly 2.5 euros each when bought in a pack.
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Copper slug rings: these are simple rings of pure copper, usually 5 cm tall, with no outward-sloping lip, to be placed around the base of the plants you want to protect. These rings cost about 6.5 euros each when bought in a pack (it’s only natural that they cost more – it’s copper, after all). They work thanks to the repellent effect that copper has on slugs. For more detail, see my comparison of every copper slug barrier on the market.
Plastic slug rings
Effectiveness test
Here, on video, is an effectiveness test of plastic slug rings.
The effectiveness of these slug rings seems reasonable according to customer feedback on various marketplaces, but a few doubts remain about the test, as the video was cut during editing at around 1 min 20, and the slug sitting at the top of the ring had in the meantime been placed at the bottom – would it have managed to get over it?
I’ll let you be the judge:
Making your own plastic slug rings
It seems possible to make your own plastic slug rings: I’ll let you see how, on video, using offcuts of plastic tubs.
It’s hard to know, though, whether this really will stop the slugs.
How to use plastic slug rings with a flared collar
Plastic slug rings are mainly used for young plants or lettuces.
When planting out or transplanting a young plant that you know is vulnerable to slug attacks, fit the plastic collar over it afterwards to keep slug attacks to a minimum.
If you garden with a mulch, it is essential to clear the mulch away, and to check that no slugs, or slug eggs, are present where the slug ring is going to be installed.
The limits of plastic slug rings, depending on the plants to be protected
Depending on the plants you are going to protect, the slug ring will lose effectiveness as the plant grows.
This is particularly the case for cucurbits and cabbages, whose large leaves will fall to the ground outside the slug ring, creating access bridges to the plant.
These plants can also, and above all, be seriously held back in their growth by a slug ring that sits too high.
And you have to be very careful about this, because once the plant is well developed, the slug ring can no longer be removed without seriously damaging it (it’s like having to take a ring off a finger whose tip has swollen up considerably).
They are also not usable for strawberries, which multiply via their shallow, creeping rhizome roots, which would stand a very good chance of being cut and broken by the slug rings being pushed into the surface soil. Because of this continuous and unpredictable spreading, strawberries also tend, above all, to be scattered across their area, which makes using these rings very awkward. The same goes for other scattered plants, such as spinach, lamb’s lettuce, and so on…
But on the other hand, these rings can be worthwhile for lettuces, as they generally don’t get too much in the way of their growth, depending on the variety.
The certain height of these rings also has the benefit of holding the leaves together better, which limits the formation of the “leaf bridges” I mentioned earlier, unlike the copper rings, which are lower.
Copper slug rings
Effectiveness test
Here, on video (first part of the video), is an effectiveness test of a vertical copper strip used to block the gastropods’ path.
It isn’t a test of the rings as such, but extrapolating the results is fairly easy to do, given that in both cases it’s a vertical section of copper to be crossed.
Enjoy the video!
How to use copper slug rings
The way you use copper slug rings is the same as for plastic slug rings: clear the planting area, check there are no gastropods on it, plant out or transplant the plant, then place the protective slug ring around it.
For plants already in place, you simply need to clear the area, check there are no slugs, and set the copper ring in place.
The limits of copper slug rings, depending on the plants to be protected
Copper slug rings are lower than plastic rings with a flared collar.
They therefore hold the larger leaves above the soil less well, so the “leaf bridges” form more easily. Like the plastic rings, they are therefore not well suited to large plants such as cabbages, courgettes, and so on…
They are also poorly suited to protecting scattered plants such as strawberries, spinach, lamb’s lettuce, and so on… Because they are designed only to protect individual, isolated plants.
On the other hand, they have the advantage of being easy to remove once the plant is big enough: most copper rings are in fact “split rings” – you can place them directly at the base of a plant, or lift them off easily, without having to slide them over the whole of the foliage.
In terms of effectiveness, it all depends on the height of the copper rings in question: below 5 cm, it is average. Above 7 cm, it is very good.
Pros and cons of these two kinds of slug ring.
Plastic slug rings:
Pros:
- Low cost
- Hold large leaves above the soil for a fairly long time
Cons:
- Can disrupt the growth of bulkier plants, and impossible to remove without damage once the plants have grown too big
- Strongly incompatible with strawberries and other scattered plants
Copper slug rings:
Pros:
- Easy to add or remove the rings at the base of the plants to be protected
- No hindrance to the growth of plants with the most vigorous foliage
Cons:
- No support for the larger leaves above the soil: because of the low height of these rings
- Higher cost
- Moderate incompatibility with strawberries and other scattered plants
Strategy and slug rings
If you’re planning to buy slug rings, it’s of course because you have slug problems in the vegetable garden.
So you should know that the best thing you can do – but perhaps you already do? – is to put in place a genuine strategy to bring the slugs in your garden under lasting control, season after season.
This strategy rests on 3 main pillars:
1. Encourage slug predators into the garden: slow worms, ground beetles, hedgehogs, and so on…
The best thing to do for this is not to kill or move the slugs! Because otherwise their predators will no longer find their food, and they’ll never settle in your garden. You can also set up various suitable shelters for them.
2. Increase the garden’s overall biodiversity, and plant species that slugs enjoy, which will spread their attacks out across your garden so they focus less on your fine rows of cabbages. More detail here: slug-repellent plants, or prevention through planting.
3. Use Slug control section of the website to protect your plants without killing or moving the slugs: for the time it takes for the predators to settle in and the plant biodiversity to develop. This is where slug rings come into their own. But personally it isn’t the solution I favour, and I’ll explain right now why:
Other barriers as alternatives to slug rings
When I explain my slug-management strategy to gardeners – and this strategy is drawn from the methods of Hervé Coves, a specialist in garden slug management – , slug rings, even when they do feature, are not among the solutions I lean on most heavily in the third point, the third strategic pillar.
Why?
Mainly because it’s often not relevant enough for the permaculture gardeners I meet, whose gardens are often nothing but a web of companion plants, intermingled and scattered.
Permaculture gardens where, in practice, the rings struggle to find their place, just as they struggle to find it in a bed of strawberries.
In this context, edging and fencing systems are preferred.
These systems make it possible to protect a whole zone of the vegetable garden, once the slugs it contains have been removed.
Here are 2 very effective edging systems:
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slug edging with a metal overhang: fairly expensive, but apparently very effective. Available here. You just have to buy them and set them up.
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water moats: free, takes a little time to set up but very effective: Proof of the effectiveness of water as a slug barrier****. To create water moats that are effective enough, you should aim for a width of at least 10 cm and a depth of at least 5 cm. The best idea is to half-bury a length of guttering with its ends blocked off, which then fills up on its own with every shower of rain.
You should also know that I’ve designed a copper-based system to fully fence off a vulnerable zone of the vegetable garden. And customer feedback is excellent: the copper mesh for slugs.
The netting can also be used, like slug rings, to protect individual plants. But, as I said, it’s something that will sometimes be difficult to set up in the most abundant permaculture gardens.
If you have a traditional garden, and your main aim is to protect rows of lettuces, slug rings are a very good solution, and will do the job perfectly.
A little more expensive per plant than the slug netting cut (segmented) to protect individual plants (allowing 50 cm of netting per plant)… But quicker to install.
The information in this article has been selected and verified according to the criteria defined in our editorial charter.
Scientific bibliography
The study examines several different substances for their ability to repel slugs and snails. The results notably revealed that copper had repellent effects.
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