One of the most common questions that we are asked, is what do we do about slugs? There is no simple answer. Last year we had a more serious slug problem in our rye field than ever before. Plants sown in October germinated and started to grow well, but were then slowly devoured by slugs over the next few months, to the point that we have had to hoe up most of the field, and re-plant with a Spring-sown crop. As a result, I have spent a lot of time recently thinking about slugs and researching into their behaviour.
Slugs Have Their Uses
The first thing to make clear is that slugs have their uses. Some animals, such as deer, or rabbits, are a complete nuisance in the garden; they simply eat the food that one is growing for oneself, and one aims to keep them out of the garden altogether if one can; this is not the case with slugs. Slugs play an important role in the breaking down of organic matter; part of their job is to digest dead leaves, stems, and root material, but it is also normal for them to feed on weak, unhealthy and dying plants.
Garden Soil
Secondly, one has to understand that the soil in our gardens is generally not as fertile as we imagine it to be. If it has been moved around by big machines during building work, the top soil will have been lost, and the soil structure destroyed. If it has been treated with fertilisers and pesticides over a number of years, it will have lost most of its microbial life. If it has been repeatedly ploughed, its top soil will have been buried. From a slug’s point of view, most plants trying to grow in these types of soil are weak and unhealthy, and fair game for being eaten. They just leave things like thistles, brambles, and nettles alone.
Sensitive Plants
Even if you have good soil, however, you can still run into the problem of slugs not deeming your crops healthy and dynamic enough to be left alone. This is particularly the case if you are trying to grow plants that are sensitive to cold, at the extreme of their geographical range, or if you are growing plants indoors, or under glass, and then planting them out. This problem is reduced if you have the patience to delay planting until the weather (and the soil) warms up, and the plants acquire more vigour.
Farming Itself
A problem related to sensitive plants is the nature of farming, and gardening, itself. The subsistence gardener aims to meet his or her basic needs from a relatively small plot of land (much smaller than would be required by a hunter gatherer). This means that they have to have quite a big impact on all aspects of the environment on that small patch; including which plants are growing there, which trees it has, and how they are managed, which animals have access to the plot, etc. If the slugs judge that the gardener has strayed too far from what is reasonable, they will attempt to devour all the crops, and the garden will return to what it would have been without human intervention.
What Eats Slugs?
The good gardener, therefore, knows that gardening is not just about getting certain plants to grow, but it is about nurturing a sustainable ecosystem, within which the chosen plants can thrive and feel at home. Part of that is having healthy populations of all the animals that, in nature, play a role in controlling slug populations. According to the literature, this includes a huge range of creatures: frogs, toads, lizards, slow worms, mice, voles, hedgehogs, foxes, badgers, blackbirds, thrushes, and owls, but also ants, beetles, and various insect larvae. In a well-functioning ecosystem, there are, therefore, a myriad of mechanisms by which slug numbers are regulated, and the aim of the subsistence gardener is to create a kind of oasis of super-fertile soil in which their chosen plants can prosper, protected by a huge diversity of wildlife ranging from micro-organisms living in the soil to birds, reptiles, amphibians, and mammals,
Scientific Knowledge and Farming Practices
Something started to go wrong with farming at some point over the past few hundred years, and instead of working to constantly enhance soil fertility, farmers steadily depleted it. This has led to a gradual decline in the population levels of all the plants and animals living on and around farm land, a fact that scientists have belatedly become aware of over the past few years, and which they have dubbed as the sixth mass extinction event. This decline has probably affected slugs as much as everything else: they have suffered from there being less organic matter in the soil overall, from it being buried when fields are ploughed, and by the fact that their predators, though declining in number, were always short of food. When you try to create a subsistence garden, all these factors are reversed, and slug numbers can explode. Rather than looking for solutions from the world of science and industry (both of which have their roots in the process leading to the ‘mass extinction’), plagues of slugs can be seen as a first step towards returning balance to the garden, and that in their wake, other, more attractive creatures will follow.
Gareth Lewis
Thank you so much for these monthly newsletters which I always read with great interest. They are of great help in understanding the whole picture!
You are a very good writer and your texts have the quality many printed books don’t!
Thank you again for all your time you invest.
K. Lehner, Germany
Thank you very much for your very differentiating article about slugs!It gives some really useful information and helps to look at the phenomenon in a more reasonable way.
N. Rolefs, Switzerland
Many thanks for your inspiring letters. Alléluia.
M. Santander, France
One trick I figured out, is to put piles of weeded weed between the rows, the slugs like that better than your precious plants, and in the morning you collect them (the slugs like to hide underneath the piles) and put them somewhere FAR away…
Lotta, Switzerland
You are a very big breath of fresh air!!
Thank you for you!
S. Loveridge, USA