Slugs and snails

Slugs and snails play a vital role in the garden ecosystem. They break down organic matter which then returns to the soil as valuable compost. Unfortunately, they don't stop at garden waste. In cultivated crops, an overabundance of snails can lead to substantial damage. A garden without any snails is an unhealthy garden, but a garden overrun by snails can quickly spoil the joy of gardening. Welcoming natural predators is key to keeping their numbers under control. Toads, birds, and hedgehogs are great slug predators. By making your garden an inviting habitat for these natural helpers, many slugs will be cleared away naturally.

In our organic garden in Rotterdam, a few plots experience heavy snail pressure. Here are several practical ways to manage them organically.

Poisons

There are chemical snail pellets on the market based on metaldehyde, but these are pure toxins. Slugs die quickly, but poisoned slugs pose a grave danger to birds and hedgehogs. These chemicals have no place in an organic garden. They also pose serious risks to young children or pets.

Hand-picking

Slugs appear after rainfall or at dusk to search for food. That is the ideal time to collect them. At the right temperature and humidity, you can gather dozens in minutes. Many of these collected slugs can be fed directly to your chickens. Laying damp cardboard or wooden boards across pathways also works wonders; as morning breaks, slugs crawl underneath looking for shelter, making them easy to pick up.

Responsible repellents and iron phosphate

An eco-friendly alternative is iron phosphate (such as Escar-Go). This compound inhibits feeding and causes slugs to retreat to their burrows where they die naturally, without posing any risk to hedgehogs or birds. It is fully biodegradable, though slugs must come into direct contact with it, so sprinkling a protective ring around delicate seedlings works best.

Sharp sand and coffee grounds

Slugs dislike dry, rough textures. Spreading sharp sand around plants provides temporary protection, though wet weather reduces its effectiveness. Coffee grounds are another natural deterrent that slugs tend to avoid. We source used coffee grounds from local cafes to protect new plantings and enrich our worm farm.

Targeted watering

Slugs thrive on damp ground, which helps them glide easily. Keep pathways and surface soil dry by watering directly at the base of plants with a watering can instead of watering the entire bed.

Physical barriers and beer traps

Bristle barriers or copper tape create difficult hurdles around garden beds. Beer traps can also catch dozens overnight, though bear in mind that strong scents attract snails from neighbouring gardens too!

Nematodes

A truly biological method is the use of beneficial microscopic roundworms (nematodes). Measuring only 0.1 mm, these organisms move through moist soil, seek out slugs, and parasitize them. Shortly after infection, the slug ceases feeding. Nematodes work best when applied collectively across adjacent garden beds so treated areas are not immediately reinvaded.

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