As sawdust and wood shavings are very dry and rough, and absorb liquids such as slime quickly, snails and slugs should be reluctant to crawl over them.
But is this true?
I did a test to find out.
Can Sawdust / Shavings Be Applied to Deter Slugs?
Spreading the shavings at least 2 inches (5cm) thick and between 20 and 40 inches (50–100cm) wide around vulnerable plants should be effective against slugs and snails.
It is essential to create broad, thick barriers, as slugs could overcome narrow strips too easily.
Test: Shavings Against Slugs and Snails
The effectiveness of sawdust as a slug control measure is repeatedly questioned.
So, I conducted a little experiment:
I put very dry wood shavings in a semicircle and then put freshly collected slugs and snails in its center.
I could then watch and record their reaction when they came into contact with the shavings.
Video: Wood Shavings Against Slugs
The video shows that the first snail a real problem with the shavings and is successfully deterred.
Unfortunately, after that, a tiny slug just creeps over the shavings with no problem and thereby shows that this method is not as effective as promised.
Later, another slug even uses the shavings as a hiding place.
Perhaps because of the cold weather, most slugs were not motivated to try.
You can see that the shavings repelled at least one snail successfully.
One positive side effect is that wood shavings also serve as mulch, suppressing weeds and preventing the soil from drying out.
One big problem is that sawdust/shavings probably lose even more of their effectiveness in rainy and moist situations.
These are the times when slugs and snails are particularly active.
So, after rainfall, new shavings should be sprinkled again as soon as possible.
But this leaves an even bigger problem: slugs might use the mulch as a home and hiding place.
If that is the case, using shavings becomes counterproductive.
Another problem can occur in windy conditions as the loose material can easily be blown away in all directions by even a soft breeze.
Then the path for snails quickly becomes free again.
Using a lot of shavings, which mainly consist of cellulose and thus carbon, can also cause the carbon–nitrogen ratio in the soil to shift in an unfavorable direction.
This is why it is best to combine the use of sawdust with nitrogen fertilizer.
For example, you could use sheep wool pellets.
This is beneficial because wool pellets also work to repel slugs and snails.
Using this kind of mulch against snails can only be recommended for a greenhouse.
This is because in the open air, wind and rain quickly destroy the protective barrier.
As the material is very cheap, you can try it out.
If you use shavings, please make sure to check regularly if slugs are using them as a hiding place.
In the end, there are probably more efficient ways to protect plants from slugs and snails.
The price of wood shavings/sawdust is low because they are a by-product of wood processing.
In the garden, you can also use shavings that are typically used for pet bedding.
Although their use against slugs is not always successful, I can recommend them as a mulch if combined with a nitrogen fertilizer and stone meal.