Water barrier against slugs & snails: In the test | Does it work?

Water is an insurmountable obstacle for land slugs and snails. This is at least a widespread opinion.

Land snails breathe air and drown if they fall into water.

I tested whether slugs and snails really cannot overcome water barriers in a small experiment.

A reader suggested simply turning slug collars upside down and filling the rim with water.

Slug collars are effective barriers, but not 100 percent safe. Therefore, their effectiveness could be increased by this simple trick.

Slug Collars | Multipack

Click on the image leads to an offer on Amazon.

Does that really work?

Snail crawls in water
Shallow water is apparently not an effective barrier.

Water barriers in the test

To test this idea, I set up a simple experiment.

As proposed, I turned a slug collar upside down and filled it with tap water. This created a trench about 1 in wide and deep (2 to 3 cm).

Then I placed freshly collected slugs and snails in the middle and recorded what happened in a time-lapse video.

Video: Snail barriers as a ditch | Time lapse

It was astonishing that a leopard slug (Limax maximus) passed the trench without any problems right at the beginning.

The large slug even crawled unimpressed a bit under the water surface before reaching the other side.

But as it progressed, it became apparent that slugs do shy away from water.

snail faces water barrier
Saucers for pot plants can also serve as water obstacles.

From minute 1:05, you can observe how a slug partially slides into the water. It loses its grip with its back end and can only pull itself out of the water with difficulty.

Finally, it falls completely into the water—from minute 1:30. It then begins to squirm in the water until it regains its footing and, with a bit of luck, finally reaches the other side.

Other slugs crawl along the water’s edge without sliding into the water, but also without any chance of reaching the other side.

At minute 1:42, one slug uses another one as a bridgehead to reach the other bank.

Finally, tree slugs have managed to cross the water. One slug has also managed to reach the other bank with great difficulty. Eight others, however, failed.

plus minus


It turns out that water is really an obstacle for slugs.

Leopards slugs, on the other hand, manage to find a foothold even underwater and can overcome small water ditches.

However, since leopard slugs are usually not a danger to plants, this method is absolutely recommendable.

Slug collars can easily be converted into a water barrier.

It is also possible to create wider water obstacles for larger areas using rain gutters or similar.

Here are some ideas on how to make your own slug and snail protection.

snails drinks water

Slug collars can be used to protect individual plants.

In addition, the video clarifies that width and depth are crucial for effectiveness.

Hence, slug collars with a wide rim are particularly suitable.

Therefore, I can highly recommend this method to prevent snails and slugs from getting into a flower or vegetable bed.

You just have to make sure that the barriers are always filled with water, then they will work.

For this reason, I am linking here to the corresponding offers.

Slug Collars | Multipack

Click on the image leads to an offer on Amazon.


In addition, it is possible to cultivate slug-resistant vegetables and herbs.

There is also a long list of flowers that slugs dislike eating.

angels trumpet slugresistant flowerWhich plants vegetables herbs slugs do not eat

Slug-resistant flowers

Slug-resistant plants

Long-term slug control focuses on attracting natural enemies of slugs and snails.

Here, you will find an overview of measures to control slugs and snails.

hedgehogs are shywhat do slugs like to eat

Attracting natural enemies

Snail and slug control overview

Peaceful Slug Control & Plant Protection

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