Here’s how to stop slugs eating your plants: lettuces, courgettes, strawberries, tomatoes and other leaves.
Slugs are wrecking your garden.
How do you cleverly stop them eating your lettuces, courgettes, strawberries and tomatoes? That’s exactly what we’ll look at here.
We’ll begin by trying to understand slugs and how they work, as a starting point that strikes me as essential.
We’ll then turn to the proven general methods that stop slugs attacking every type of plant: chiefly, effective slug barriers. And you’ll see that very few of them genuinely work over the long term!
After that, we’ll get into the specifics of each type of plant: protecting courgettes, strawberries, lettuces, tomatoes, flowers, leaves more specifically, and finally the vegetable patch in a more general sense.
I can promise you’ll come away with a much clearer view of the whole question. But above all, you’ll finally have concrete, proven tools to put in place at home.
So if today’s menu tempts you, let’s get started!
If you're discovering my blog, chances are slugs and snails are giving you grief.
You'd probably be very interested in the copper slug barrier I designed .
It changed everything for me. I can finally grow lettuce, cabbages, strawberries and squashes without tearing my hair out.
Don't hesitate — it's an investment (copper is expensive), but you'll likely save yourself a huge amount of time!
Understanding Slugs
The biology of slugs
The slug life cycle
Slugs, though often inconspicuous, have a life cycle that helps them persist in our gardens.
The cycle begins with the laying of eggs, generally in spring or autumn, the seasons when moisture is plentiful.
Adult slugs lay their eggs in small clusters, hidden away in dark, damp spots, such as under fallen leaves or in loose soil.
After a few weeks, the eggs hatch, giving rise to juvenile slugs that start feeding straight away.
Young slugs go through several growth stages before reaching adult size, a process that can take anything from a few months to a year, depending on the species and the environmental conditions.
Once adult, slugs can live for up to two years. During this time they keep feeding actively and breeding, which can quickly lead to an infestation if they aren’t kept in check.
Preferred habitat and conditions that favour their spread
Slugs are particularly drawn to damp, shady surroundings.
They prefer soils rich in organic matter, where they can hide away and find food in abundance. Gardens with dense vegetation, compost heaps or uncleared organic debris offer ideal habitats for these molluscs.
Climatic conditions also play a crucial role in their spread.
Prolonged spells of rain or high humidity encourage their activity, while dry spells can reduce their numbers.
That said, slugs are able to survive unfavourable conditions by burrowing into the soil or taking shelter under objects to avoid drying out.
Feeding behaviour
Plants and plant parts that slugs prefer
Slugs are voracious herbivores, feeding mainly on soft plant tissue.
They show a marked preference for young plants and tender leaves, but they can also attack ripe fruit and roots.
Leafy vegetables such as lettuces, spinach or cabbages are particularly vulnerable, as are young courgette shoots, certain flowers, strawberries (the fruit) and so on. In general, any plant with tender and/or juicy parts is liable to be attacked by slugs.
The impact of the seasons and weather conditions on their activity
Slug activity is heavily influenced by the seasons and the weather.
They are at their most active during the damp months of spring and autumn, when temperatures are mild and the soil stays moist.
In summer, particularly during dry spells, their activity often eases off, as they try to avoid the heat and dehydration. But they can resume their activity as soon as conditions become more favourable.
In winter, in regions where temperatures stay mild, slugs can remain active, albeit in a limited way.
In colder regions, they slow their metabolism and become dormant, hiding away in sheltered spots until temperatures climb back up.
General methods for stopping slugs eating the plants in your garden
In this part we’ll look at the ways of limiting the damage done by the slugs already present in your vegetable patch.
In the next part, we’ll see how to cut down the number of slugs in your garden in the first place, which is a more wide-ranging, more lasting approach, but also a less immediate one (there’s a certain delay between the actions you take and the results, unlike what we’re about to cover right now).
Slug traps
You’ve probably heard of these already. Beer traps, in particular.
Yet you’ll want to rule out this method, which lures slugs in from far and wide into your garden (drawn by the smell of the beer), while only a third of the slugs attracted end up drowning in the famous beer trap. Do the maths: if your plot isn’t several hundred square metres, you’ll end up with more slugs than before by using this method.
No, the slug traps I recommend are traps that are attractive but not too much so: for example, a simple plank or tile laid on the ground, under which you’ve scattered a few peelings.
In the morning, or at night, you can then lift the plank and gather up the slugs assembled there. More than a trap, it’s really a method that makes the slugs easier to collect.
Even so, you’ll see in the next part that it isn’t necessarily wise to collect slugs in order to “remove” them from the garden, by carrying them a long way off, for instance. The same goes if you decide to do away with them instead.
Slug-repelling plants
A very useful method consists in putting the benefits of slug-repelling plants to good use. There are 4 main types: plants that repel slugs (these are rare), plants that are resistant to slugs (a preventive measure that limits damage upstream), plants that slugs love (which you use as sacrificial plants, to divert the slugs’ attention away from your vegetables or ornamentals), and plants that attract the slugs’ predators.
Learn to wield slug-repelling plants the way D’Artagnan wields a sword, and you’ll start to see some genuinely big improvements at home.
Slug barriers
Slug barriers, meaning anything capable of stopping slugs getting through.
These barriers are used to stop slugs reaching your plants, and therefore to stop them eating them.
I know, you’re now thinking of eggshells, ash, coffee grounds…
But you should know that almost all of these old wives’ remedies aren’t effective, certainly not in the long run.
If you have any doubts, take a look at my video tests here.
Only two barriers turn out to be genuinely effective over time: water (used in the form of a moat, with buried guttering for instance), and copper, used in the form of a vertical barrier more than 7 cm high.
In fact, off the back of my tests I designed a slug barrier made from copper. And it proved so effective that I now sell it, here: the copper mesh for slugs.
Borage is one of the only plants said to have a genuine repellent effect on slugs.
General methods for reducing the number of slugs in your garden
Attracting the slugs’ natural predators
The slugs’ predators are the foundation on which to pin our hopes of a slug-free garden (or one with far fewer slugs), over the long term.
Once the slugs’ natural predators have settled in at your place, they work 7 days a week to cut down the number of slugs in your garden.
To find out more on the subject, I can only recommend this article: getting to know and welcoming the slugs’ predators
Don’t kill or move slugs
The essential prerequisite for this first point is not killing or moving the slugs in your garden.
Because if the slugs’ predators can no longer find their food, they’ll never settle in, and you’ll spend years chasing the problem.
So don’t kill and don’t move slugs, if you want the problem to be resolved for good (and cleverly).
Don’t use counterproductive methods
Don’t use methods that work against what you’re trying to achieve.
I’m referring to beer traps (already mentioned), slug pellets (which kill + harm biodiversity), diatomaceous earth (likewise), and killing slugs in general.
Avoid these methods, and your slug problem will be resolved all the faster.
The hedgehog is a predator of slugs.
Specific solutions for stopping slugs eating different plants
Let’s now look at the particular points that can apply to different types of plant, to help you maximise their protection.
We’ll only cover protection strategies here, not reducing the number of slugs in the garden.
Lettuces
Use water moats deep enough (> 5 cm, and > 10 cm wide) around a lettuce bed.
Use the slug netting around this same kind of lettuce bed.
Particularly fragile lettuces can be protected individually, as a complement. With the slug netting, cut off a section about thirty centimetres long and slip it on, like a sock (the netting is sock-shaped), around each plant you want to protect.
Removing the mulch from the growing bed in the first few weeks after planting can also help to reduce the presence of slugs (by reducing the bed’s moisture and their hiding places).
Plant slug-repelling plants from all 4 categories nearby or in the lettuce bed.
Courgettes (young)
Young courgettes, and cucurbits in general, are very sensitive to slugs.
Personally, I use the slug netting as individual protection only around the young plants (straight after planting), then remove it once the plants are sturdy enough.
Removing the mulch during the first few weeks after planting is another option worth considering. It also lets the soil warm up more quickly, which is very useful early in the season.
Strawberries (the fruit)
For strawberries, individual protection is too complicated to manage.
Use water moats or the slug netting around the strawberry bed.
Use slug-repelling plants too.
Sensitive flowers
Potted flowers can be protected with self-adhesive copper tape, stuck around the pot.
Make sure the total width of the adhesive tape is more than 7 cm. And that it forces a vertical crossing. Don’t stick it on horizontally, that won’t work.
Leaves, in general
A common problem is large, drooping leaves that touch the ground on the other side of the barrier you’ve put in place. And which therefore often get devoured.
The solution:
Make sure the leaves don’t touch the ground. For example by holding them up with stakes.
Conclusion
Living alongside the lady slugs is no easy task!
Nevertheless, solutions do exist.
You simply need to know which ones genuinely work (and that’s no simple matter, I’ve had to run plenty of tests…).
And to apply them methodically and conscientiously.
So that after a few days, you finally reach the point of protected plants.
And after 2 to 5 years, a garden where slugs no longer swarm, inhabited instead by a horde of formidable predators of these gastropods.
I hope you’ve enjoyed this article, and that it’s given you new tools to garden freely and self-sufficiently, all while understanding what you’re doing and why you’re doing it.
See you soon,
Robin.
The information in this article has been selected and verified according to the criteria defined in our editorial charter.
Done with slugs. For good. Starting this season.
Scientific references
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