Natural pest control: slugs and snails

In this series , Gardeners' World magazine and Rootsum, experts in organic solutions, give advice to six of our readers, who have submitted their pest problems to us. This time in the series, José is looking for those who expertly strip her Crambe (sea kale) bare each spring.

“ Every year I have had a beautiful flowering Crambe in my garden. For 2 years now it has only gotten a few leaves, which are also being eaten… are they mice or an insect? What is the solution? ” – José Arts

What a waste of your sea kale! That is indeed a beautiful plant to have. Several animals can nibble on the young leaves, such as pigeons and mice. What is perhaps more obvious are snails. Slugs in particular are fond of cabbage and in the spring small slugs will be able to hide very well, which can make tracking difficult and the cause of the feeding is not always immediately clear.

Slugs are notorious in the garden and especially seedlings and emerging plants will suffer from an overpopulation. Fortunately, you can combat them effectively, in an organic way, namely with nematodes of Phasmarhabditis californica .

These tiny nematodes penetrate the body of the snail, and by introducing specific bacteria, the snail stops eating and will eventually die. The nematodes reproduce and the new nematodes will then seek out new snails to parasitize. After introduction, most snails will disappear after 2 weeks. In total, the nematodes remain active in the control for up to 6 weeks, after which they are often eaten themselves or infected with fungi that kill them. In this way, these animals do not form a plague themselves.

In addition to nematodes, you can also protect your seedlings very effectively with anti-slug rings . These rings are placed around your seedlings and the specially designed surface prevents slugs from crawling over them. Your plants can grow into strong plants in this way.

Slugs (and garden snails) are real gluttons and in wet years they can become a real plague in your garden. Don't forget that slugs are also an important part of your garden ecosystem and that they also have a use, for example for keeping unwanted plants and as food for thrushes (snails) and amphibians (including small slugs). Nevertheless, if they are a real nuisance, it is necessary to tackle them, because otherwise there will be little left of your beloved seedlings and garden plants.

The cause of the large number of snails is not always easy to determine, but improving the natural balance in your garden can certainly help. These tips can help you attract more animals that will deal with your snails:

Make a (mini) pond with native plants, with which you can attract frogs, but also provide water for thrushes and other animals. This way they like to come to your garden and pick up a snail.
A messy corner, access to your garden and a (good) hedgehog box can help attract hedgehogs. Hedgehogs eat all kinds of insects, but also like to pick up snails.
Do you come across a tiger snail ( Limax maximus )? Then let it walk around. It sometimes eats leaves, but is especially fond of other snails!
Use shell grit, sheep wool or copper bands around your most vulnerable plants: snails don't like to go over these. Check whether a snail is inside the protection, it will then not leave.

Do you have a garden with a lot of biodiversity, but still far too many snails? Then you can also combat them in other ways.

A good way is the nematodes , as described above.
You can set beer traps, which attract slugs and drown in them. Dig a container or jar to the edge and fill it halfway with beer. The next day, remove the contents of the jar, with the slugs in it.
Collect the snails in a bucket in the evening, when it is dark and preferably somewhat damp weather. Remove the snails from the garden. Note: do not release them close to your garden, because they will simply crawl back.

For 30 years, the Belgian family business Rootsum from Leuven (formerly known as BioGroei) has been developing natural solutions for pests in organic gardening. 'In search of beastly creatures', as they also call it. They do this by offering organic alternatives to poison, improving the soil and focusing on creating biodiverse gardens throughout Flanders and the Netherlands.