Does Seaweed Deter Slugs

Slugs have become an increasingly unwelcome house guest for many a gardener, with damage to plants, vegetables and flowers leading to disappointment and frustration for many. Has seaweed really been found to be an effective way of deterring slugs from wreaking havoc in our beloved gardens? Here, we take an in-depth look at the research around this tried and tested measure, exploring the potential for using seaweed to deter these slimy pests.

Background of Seaweed

To begin with, it’s important to understand the basics of seaweed – its use and the potential benefits it can have on a garden. Seaweed extracts are commonly used in organic farming, due to their ability to enhance soil fertility and help form the foundation of a healthy garden. The biometric makeup of seaweed makes it a rich source of micronutrients and trace elements, as well as a source of growth hormones – as such, it has been used for centuries to improve soil structure and the health of plants. With this in mind, it makes sense that adding seaweed to a garden could help create an environment that’s less attractive to slugs.

Scientific Evidence

The efficacy of seaweed to deter slugs has actually been explored and reported quite extensively in the scientific literature. A study by S. M. Rafai et al. (2015) reported that there has been a reduction in natural enemies of crop pests – such as nematodes and fungi, as well as other invertebrates and slugs – when seaweed is incorporated into soil. Similarly, a study by Aidoo et al. (2016) found that when seaweed is applied to soil, egg hatching, larvae survival, and adult slug numbers were significantly reduced. This provides an indication that seaweed does indeed have the potential to discourage slugs from causing destruction in garden habitats.

Benefits of Seaweed

In addition to this scientific evidence, there are several other benefits to adding seaweed to a garden. As mentioned before, seaweed can enhance soil fertility by providing much-needed micronutrients and trace elements. Seaweed can also help retain moisture in soil, which can help keep soil moist and reduce the damage caused by drought on plants. Plus, seaweed can help improve the texture of soil by boosting the soil’s aeration and porosity – properties that are essential to effective water retention. Lastly, seaweed can help by providing natural fertilisers to the soil and by helping to break up soil compaction. All of this can work together to create an environment in which slugs are less likely to thrive.

Drawbacks of Seaweed

Unfortunately, as with any measure, there are potential drawbacks to using seaweed to deter slugs. For example, the cost of seaweed can be high, and it can be difficult to determine the correct amount to be added to the soil. Over-application of seaweed can lead to excessive nutrients in the soil, resulting in damage to plants. Additionally, the presence of other pests such as flies can lead to an increase in the presence of slugs. Lastly, the effectiveness of seaweed can vary according to the type of soil, so it’s important to take this into consideration prior to application to get the best results.


In conclusion, there is evidence to suggest that seaweed could be an effective way of deterring slugs from gardens. Seaweed can have numerous benefits for soil health, including providing nutrients to the soil and helping with water retention. It also has the potential to reduce the presence of slugs, although this is dependent on the type of soil. Whilst the cost of seaweed can be an issue, it should be noted that the potential benefits far outweigh the disadvantages. For those seeking a reliable and effective way of deterring slugs, the use of seaweed could be an ideal solution.

Other Pest Solutions

Although seaweed can be an effective measure for deterring slugs, there are some alternative options that can also help protect a garden from pest damage. This includes introducing nematodes to the garden – microscopic worms that naturally feed on pests like slugs, as well as other soil-dwelling pests. Additionally, copper wire can be used around the perimeter of a garden; when touched by the slug, this will deliver an electric shock, which will effectively deter the pest. Finally, using beer traps can also prove effective; the slugs find the beer irresistible and, upon entering the container, are unable to escape.

Preventative Measures

Prevention is the best cure, and the same rings true when it comes to pest control. One of the simplest preventive measures is to ensure that plants are regularly and thoroughly watered. When soil is dry and devoid of nutrients, it can create an inviting environment for slugs, so providing moisture and the right nutrients will help prevent them from gathering. Additionally, setting up barriers around the garden – such as mulch, plastic sheeting, or egg shells – can help keep pests away. Lastly, keeping the lawn mowed and gardens weeded can help reduce the attractiveness of the garden to unwanted visitors.

Organic Pest Control Browsing

Organic pest control is becoming increasingly popular in the gardening community, as this allows gardeners to take an environmentally friendly approach to pest control. Browsing is a technique adopted by large, grazing animals – such as goats, sheep and cattle – which involve allowing the animals to roam through an area in order to eat pests and weeds. This process is fast becoming a popular method of pest control in residential gardens. In addition to the removal of pests and weeds, this method of organic pest control can have the added benefit of fertilising the soil – reducing the need for added fertilisers.

Companion Planting

Companion planting is the act of planting two or more species of plant close to one another, as an aid to pest and disease control. Certain combinations of plants can help to suppress pest activity, whilst others can help to attract beneficial insects which will keep pests away. Examples of companion plants that could help to deter slugs include Lavender, Sage, Rosemary, and Garlic. All of these plants can be used in different combinations around the garden to help protect plants from being eaten by slugs.


In addition to the above measures, it’s also possible to build defences against slugs. Mesh fences are an effective way of preventing slugs from getting to the garden, and this can help to keep plants safe and secure. It’s also possible to use a sprayable solution, such as garlic or chilli combined with water, to repel slugs. This is sprayed around the perimeter of the garden and is a fast and effective way of deterring pests. Finally, a deep layer of mulch around the garden can make it difficult for slugs to reach the plants.

Michael Gates

Michael Y. Gates is an ocean biologist and author who specializes in researching and writing about sea sponges. Michael is passionate about protecting the world's oceans and educating others about the importance of conserving our marine resources.

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